Nuvoton 8-bit 8051-based Microcontroller
N78E517A
Data Sheet
N78E517A Data Sheet
TABLE OF CONTENTS
1. DESCRIPTION .................................................................................................................................................. 4
2. FEATURES ....................................................................................................................................................... 5
3. BLOCK DIAGRAM ............................................................................................................................................ 7
4. PIN CONFIGURATIONS ................................................................................................................................... 8
5. MEMORY ORGANIZATION ............................................................................................................................ 14
5.1 Internal Program Memory ................................................................................................................. 14
5.2 External Program Memory ................................................................................................................ 16
5.3 Internal Data Memory ....................................................................................................................... 17
5.4 On-chip XRAM .................................................................................................................................. 19
5.5 External Data Memory ...................................................................................................................... 19
5.6 On-chip Non-volatile Data Flash ....................................................................................................... 20
6. SPECIAL FUNCTION REGISTER (SFR) ....................................................................................................... 23
7. GENERAL 80C51 SYSTEM CONTROL ......................................................................................................... 26
8. AUXILIARY RAM (XRAM) ............................................................................................................................... 30
9. I/O PORT STRUCTURE AND OPERATION .................................................................................................. 32
10. TIMERS/COUNTERS.................................................................................................................................... 36
10.1 Timer/Counters 0 and 1 .................................................................................................................. 36
10.1.1 Mode 0 (13-bit Timer) ...................................................................................................... 38
10.1.2 Mode 1 (16-bit Timer) ...................................................................................................... 39
10.1.3 Mode 2 (8-bit Auto-reload Timer) .................................................................................... 39
10.1.4 Mode 3 (Two Separate 8-bit Timers) ............................................................................... 40
10.2 Timer/Counter 2 .............................................................................................................................. 41
10.2.1 Capture Mode .................................................................................................................. 44
10.2.2 Auto-reload Mode ............................................................................................................ 44
10.2.3 Baud Rate Generator Mode ............................................................................................ 45
10.2.4 Clock-out Mode................................................................................................................ 46
11. WATCHDOG TIMER ..................................................................................................................................... 47
11.1 Functional Description of Watchdog Timer ..................................................................................... 47
11.2 Applications of Watchdog Timer ..................................................................................................... 49
12. POWER DOWN WAKING-UP TIMER .......................................................................................................... 50
12.1 Functional Description of Power Down Waking-up Timer .............................................................. 50
12.2 Applications of Power Down Waking-up Timer............................................................................... 51
13. SERIAL PORT ............................................................................................................................................... 53
13.1 Mode 0 ............................................................................................................................................ 55
13.2 Mode 1 ............................................................................................................................................ 57
13.3 Mode 2 ............................................................................................................................................ 59
13.4 Mode 3 ............................................................................................................................................ 61
13.5 Baud Rate ....................................................................................................................................... 63
13.6 Multiprocessor Communication....................................................................................................... 64
14. SERIAL PERIPHERAL INTERFACE (SPI) ................................................................................................... 66
14.1 Features .......................................................................................................................................... 66
14.2 Functional Description .................................................................................................................... 66
14.3 Control Registers of SPI ................................................................................................................. 69
14.4 Operating Modes ............................................................................................................................ 71
14.4.1 Master mode .................................................................................................................... 71
14.4.2 Slave Mode ...................................................................................................................... 71
14.5 Clock Formats and Data Transfer ................................................................................................... 72
14.6 Slave Select Pin Configuration ....................................................................................................... 74
-2-
14.7 Mode Fault Detection ...................................................................................................................... 75
14.8 Write Collision Error ........................................................................................................................ 75
14.9 Overrun Error .................................................................................................................................. 75
14.10 SPI Interrupts ................................................................................................................................ 76
15. PULSE WIDTH MODULATOR (PWM) ......................................................................................................... 77
16. TIMED ACCESS PROTECTION (TA)........................................................................................................... 81
17. INTERRUPT SYSTEM .................................................................................................................................. 83
17.1 Priority Level Structure .................................................................................................................... 89
17.2 Interrupt Latency ............................................................................................................................. 91
18. IN SYSTEM PROGRAMMING (ISP) ............................................................................................................. 92
18.1 ISP Procedure ................................................................................................................................. 92
18.2 ISP Commands ............................................................................................................................... 95
18.3 User Guide of ISP ........................................................................................................................... 95
18.4 ISP Demo Code .............................................................................................................................. 96
19. POWER SAVING MODES .......................................................................................................................... 100
19.1 Idle Mode ...................................................................................................................................... 100
19.2 Power Down Mode ........................................................................................................................ 101
20. CLOCK SYSTEM ........................................................................................................................................ 103
20.1 12T/6T mode ................................................................................................................................. 103
20.2 External Clock Source .................................................................................................................. 105
20.3 On-chip RC Oscillator ................................................................................................................... 105
21. POWER MONITORING .............................................................................................................................. 106
21.1 Power-on Detection ...................................................................................................................... 106
21.2 Brown-out Detection ..................................................................................................................... 106
22. RESET CONDITIONS ................................................................................................................................. 110
22.1 Power-on Reset ............................................................................................................................ 111
22.2 Brown-out Reset ........................................................................................................................... 111
22.3 RST Pin Reset .............................................................................................................................. 111
22.4 Watchdog Timer Reset ................................................................................................................. 112
22.5 Software Reset.............................................................................................................................. 112
22.6 Boot Select .................................................................................................................................... 113
22.7 Reset State ................................................................................................................................... 114
23. AUXILIARY FEATURES ............................................................................................................................. 116
24. CONFIG BYTES .......................................................................................................................................... 117
25. INSTRUCTION SET .................................................................................................................................... 121
26. ELECTRICAL CHARACTERISTICS ........................................................................................................... 125
26.1 Absolute Maximum Ratings .......................................................................................................... 125
26.2 DC Electrical Characteristics ........................................................................................................ 125
26.3 AC Electrical Characteristics ......................................................................................................... 131
27. PACKAGES ................................................................................................................................................. 135
28. DOCUMENT REVISION HISTORY ............................................................................................................ 140
-3-
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
1. DESCRIPTION
N78E517A is an 8-bit microcontroller, which has an in-system programmable Flash supported. The instruction
set of N78E517A is fully compatible with the standard 8051. N78E517A contains a maximum 64k[1] bytes of
main Flash APROM, in which the contents of the main program code can be updated by parallel Programmer/Writer or In System Programming (ISP) method which enables on-chip firmware updating. There is an additional 2.5k bytes called LDROM for ISP function. N78E517A has a configurable size of Data Flash [1] which is
64k-byte shared with APROM, accessed with ISP. N78E517A provides 256 bytes of SRAM, 1k bytes of auxiliary RAM (XRAM), four 8-bit bi-directional and bit-addressable I/O ports, an additional 8-bit bi-directional and bitaddressable port P4 for LQPF-48 package (PLCC-44, PQFP-44, and TQFP-44 just have low nibble 4 bits of
P4 and DIP-40 does not have this additional P4), three 16-bit Timers/Counters, one UART, five PWM output
channels, and one SPI. These peripherals equip with 11-source with 4-level priority interrupts capability. To
facilitate programming and verification, the Flash inside the N78E517A allows the Program Memory to be programmed and read electronically. Once the code confirms, the user can lock the code for security.
N78E517A is built in a precise on-chip RC oscillator of 22.1184MHz/11.0592MHz selected by CONFIG setting,
factory trimmed to ±1% at room temperature. N78E517A provides additional power monitoring detection such
as power-on and Brown-out detection. It stabilizes the power-on/off sequence for a high reliability system design.
N78E517A microcontroller operation consumes a very low power. Two economic power modes to reduce power consumption, Idle mode and Power Down mode. Both of them are software selectable. The Idle mode turns
off the CPU clock but allows continuing peripheral operation. The Power Down mode stops the whole system
clock for minimum power consumption.
[1] Data Flash and APROM share 64k-byte space.
-4-
2. FEATURES
Fully static design 8-bit CMOS microcontroller.
Wide supply voltage of 2.4V to 5.5V and wide frequency from 4MHz to 40MHz.
12T mode compatible with the tradition 8051 timing.
6T mode supported for double performance.
On-chip RC oscillator of 22.1184MHz/11.0592MHz, trimmed to ±1% at room temperature for the precise
system clock.
Maximum 64k bytes Flash APROM for the application program.
2.5k bytes Flash LDROM for ISP code.
Configurable size of Data Flash, 64k-byte shared with APROM.
In-System-Programmable (ISP) built in. ISP Erasing or programming supports wide operating voltage 3.0V
to 5.5V.
Flash 10,000 writing cycle endurance. Greater than 10 years data retention under 85℃.
256 bytes of on-chip RAM.
1k bytes of on-chip auxiliary RAM (XRAM).
64k bytes Program Memory address space and 64k bytes Data Memory address space.
Maximum five 8-bit general purpose I/O ports pin-to-pin compatible with standard 8051, additional INT2
and INT3 on packages except DIP-40.
Three 16-bit Timers/Counters.
One dedicate timer for Power Down mode waking-up.
One full-duplex UART port.
Five pulse width modulated (PWM) output channels.
One SPI communication port.
11-source, 4-priority-level interrupts capability.
Programmable Watchdog Timer.
Power-on reset.
Brown-out detection interrupt and reset, 4-level selected.
Supports software reset function.
Built-in power management with Idle mode and Power Down mode.
-5-
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Code lock for data security.
Much lower power consumption than other standard 8051 productions.
Industrial temperature grade, -40℃to +85℃ range.
Strong ESD, EFT immunity.
Development Tool:
– Parallel Programmer/Writer.
– Nuvoton 8-bit Microcontroller ISP Writer.
Package:
Part Number
N78E517ADG
APROM
Data Flash
Shared 64k bytes
Package
40-pin DIP
N78E517APG
44-pin PLCC
N78E517AFG
44-pin PQFP
N78E517ATG
44-pin TQFP
N78E517ALG
48-pin LQFP
-6-
3. BLOCK DIAGRAM
Figure 3–1 shows the functional block diagram of N78E517A. It gives the outline of the device. The user can
find all the device‟s peripheral functions in the diagram.
Brownout and
low voltage
detection
VDD
VSS
12T 80C51 CPU
RST
2.5k Bytes
LDROM Flash
Serial Port
(UART)
Data Flash
Shared 64k Bytes
with APROM
SPI
256 Bytes
Internal RAM
PWM
1024 Bytes
XRAM
(Auxiliary RAM)
P0[7:0]
P1[7:0]
P2[7:0]
P3[7:0]
P4[7:0]
8
8
8
8
8
I/O Port, P0
8-bit Internal Bus
Max. 64k Bytes
APROM Flash
Timer0
Timer 1
Timer 2
T0 (P3.4)
T1 (P3.5)
T2 (P1.0)
T2EX (P1.1)
TXD (P3.1)
RXD (P3.0)
SS (P1.4)
MOSI (P1.5)
MISO (P1.6)
SPCLK (P1.7)
5
PWM0~PWM4
(P1.3~P1.7)
INT0 (P3.2)
INT1 (P3.3)
INT2 (P4.3)
INT3 (P4.2)
External
Interrupt
Watchdog
Timer
Power Down
Waking-up Timer
I/O Port, P1
8
8
I/O Port, P2
External Memory
Bus Interface
I/O Port, P3
AD[7:0] (P0[7:0])
A[15:8] (P2[7:0])
ALE
PSEN
WR (P3.6)
RD (P3.7)
I/O Port, P4
System
Clock
Power
Management
XTAL1
XTAL2
Oscillating
Circuit
12T/6T Divider
On-chip RC
Oscillator
Figure 3–1. N78E517A Function Block Diagram
-7-
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
4. PIN CONFIGURATIONS
T2, P1.0
1
40
VDD
T2EX, P1.1
2
39
P0.0, AD0
P1.2
3
38
P0.1, AD1
PWM0, P1.3
4
37
P0.2, AD2
SS, PWM1, P1.4
5
36
P0.3, AD3
6
35
P0.4, AD4
7
34
P0.5, AD5
SPCLK, PWM4, P1.7
8
33
P0.6, AD6
RST
9
32
P0.7, AD7
31
EA
RXD, P3.0
10
DIP 40-pin
MOSI, PWM2, P1.5
MISO, PWM3, P1.6
TXD, P3.1
11
30
ALE
INT0, P3.2
12
29
PSEN
INT1, P3.3
13
28
P2.7, A15
T0, P3.4
14
27
P2.6, A14
T1, P3.5
15
26
P2.5, A13
WR, P3.6
16
25
P2.4, A12
RD, P3.7
17
24
P2.3, A11
XTAL2
18
23
P2.2, A10
XTAL1
19
22
P2.1, A9
VSS
20
21
P2.0, A8
Figure 4–1. Pin Assignment of DIP 40-Pin
AD0, P0.0
AD1, P0.1
AD2, P0.2
AD3, P0.3
43
42
41
40
1
44
INT3, P4.2
2
VDD
T2, P1.0
3
5
4
6
P1.2
PWM0, P1.3
T2EX, P1.1
SS, PWM1, P1.4
MOSI, PWM2, P1.5
7
39
P0.4, AD4
MISO, PWM3, P1.6
8
38
P0.5, AD5
SPCLK, PWM4, P1.7
9
37
P0.6, AD6
RST
10
36
P0.7, AD7
35
EA
34
P4.1
RXD, P3.0
11
INT2, P4.3
12
TXD, P3.1
13
33
ALE
INT0, P3.2
14
32
PSEN
INT1, P3.3
15
31
P2.7, A15
T0, P3.4
16
30
P2.6, A14
T1, P3.5
17
29
P2.5, A13
PLCC 44-pin
27
28
P2.1, A9
P2.2, A10
P2.3, A11
P2.4, A12
VSS
26
XTAL1
25
22
XTAL2
P2.0, A8
21
P3.7, RD
P4.0
20
P3.6, WR
24
19
23
18
Figure 4–2. Pin Assignment of PLCC 44-Pin
-8-
SS, PWM1, P1.4
PWM0, P1.3
P1.2
T2EX, P1.1
T2, P1.0
INT3, P4.2
VDD
AD0, P0.0
AD1, P0.1
AD2, P0.2
AD3, P0.3
44
43
42
41
40
39
38
37
36
35
34
MOSI, PWM2, P1.5
1
33
P0.4, AD4
MISO, PWM3, P1.6
2
32
P0.5, AD5
SPCLK, PWM4, P1.7
3
31
P0.6, AD6
RST
4
30
P0.7, AD7
RXD, P3.0
5
29
EA
INT2, P4.3
6
28
P4.1
TXD, P3.1
7
27
ALE
INT0, P3.2
8
26
PSEN
INT1, P3.3
9
25
P2.7, A15
T0, P3.4
10
24
P2.6, A14
T1, P3.5
11
23
P2.5, A13
PQFP/TQFP 44-pin
18
19
20
21
22
P4.0
P2.0, A8
P2.1, A9
P2.2, A10
P2.3, A11
P2.4, A12
VSS
17
16
XTAL1
XTAL2
15
14
P3.7, RD
P3.6, WR
13
12
Figure 4–3. Pin Assignment of PQFP/TQFP 44-Pin
P4.4
SS, PWM1, P1.4
PWM0, P1.3
P1.2
T2EX, P1.1
T2, P1.0
INT3, P4.2
VDD
AD0, P0.0
AD1, P0.1
AD2, P0.2
AD3, P0.3
48
47
46
45
44
43
42
41
40
39
38
37
MOSI, PWM2, P1.5
1
36
P4.7
MISO, PWM3, P1.6
2
35
P0.4, AD4
SPCLK, PWM4, P1.7
3
34
P0.5, AD5
RST
4
33
P0.6, AD6
RXD, P3.0
5
32
P0.7, AD7
INT2, P4.3
6
31
EA
LQFP 48-pin
TXD, P3.1
7
30
P4.1
INT0, P3.2
8
29
ALE
INT1, P3.3
9
28
PSEN
T0, P3.4
10
27
P2.7, A15
T1, P3.5
11
26
P2.6, A14
P4.5
12
25
P2.5, A13
23
24
P2.3, A11
P2.4, A12
P4.6
P2.2, A10
22
P2.1, A9
VSS
21
XTAL1
P2.0, A8
17
XTAL2
20
16
P3.7, RD
19
15
P3.6, WR
P4.0
14
18
13
Figure 4–4. Pin Assignment of LQFP 48-Pin
-9-
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Table 4–1. Pin Description
Pin number
DIP
19
Alternate Function
PQFP
PLCC
LQFP
TQFP
21
15
16
Type
Symbol
1
XTAL1
[1
]
Description
I
(ST)
CRYSTAL1: This is the input pin to the internal
inverting amplifier. The system clock is from external crystal or resonator when FOSC (CONFIG3.1)
is logic 1 by default.
A 0.1μF capacitor is recommended to be added
on XTAL1 pin to gain the more precise frequency of the internal RC oscillator frequency if it is
selected as the system clock source.
2
18
20
14
15
XTAL2
O
CRYSTAL2: This is the output pin from the internal
inverting amplifier. It emits the inverted signal of
XTAL1. While on-chip RC oscillator is used, float
XTAL2 pin always.
40
44
38
41
VDD
P
POWER SUPPLY: Supply voltage VDD for operation.
20
22
16
17
VSS
P
GROUND: Ground potential.
I
EXTERNAL ACCESS ENABLE: To force EA low
will make the CPU execute the external Program
Memory. The address and data will be presented
on the bus P0 and P2. If the EA pin is high, CPU
will fetch internal code unless the Program Counter
addresses the area out of the internal Program
Memory. It will make CPU run external Program
Memory continuously.
EA possesses reset lock. After all reset, the EA
state will be latched and any state change of this
pin after reset will not switch between internal and
external Program Memory execution.
The user should take care of this pin from floating but connecting to VDD directly if internal
Program Memory is used.
O
ADDRESS LATCH ENABLE: ALE is used to enable the address latch that separates the address
from the data on Port 0. ALE runs at 1/6 of the
[2]
Fosc . An ALE pulse is omitted always.
The user can turn ALE off by setting ALEOFF
(AUXR.0) to reduce EMI. Setting ALEOFF will just
make ALE activating only during external memory
access through a MOVC or MOVX instruction. ALE
will stay high in other conditions.
O
PROGRAM STORE ENABLE: PSEN strobes the
external Program Memory. When internal Program
Memory access is performed, there will be no
PSEN strobe signal output from this pin.
31
30
29
35
33
32
29
27
26
31
EA
29
ALE
28
PSEN
- 10 -
Table 4–1. Pin Description
Pin number
DIP
Alternate Function
PQFP
PLCC
LQFP
TQFP
Type
Symbol
[1
]
1
Description
2
I
(ST)
9
10
4
4
RST
39
43
37
40
P0.0
AD0
D, I/O
38
42
36
39
P0.1
AD1
D, I/O
37
41
35
38
P0.2
AD2
D, I/O
36
40
34
37
P0.3
AD3
D, I/O
35
39
33
35
P0.4
AD4
D, I/O
34
38
32
34
P0.5
AD5
D, I/O
33
37
31
33
P0.6
AD6
D, I/O
32
36
30
32
P0.7
AD7
D, I/O
1
2
40
43
P1.0
T2
I/O
2
3
41
44
P1.1
T2EX
I/O
3
4
42
45
P1.2
4
5
43
46
P1.3
PWM0
5
6
44
47
P1.4
PWM1
SS
I/O
6
7
1
1
P1.5
PWM2
MOSI
I/O
7
8
2
2
P1.6
PWM3
MISO
I/O
8
9
3
3
P1.7
PWM4
SPCLK
I/O
21
24
18
19
P2.0
A8
I/O
22
25
19
20
P2.1
A9
I/O
23
26
20
21
P2.2
A10
I/O
24
27
21
22
P2.3
A11
I/O
25
28
22
23
P2.4
A12
I/O
26
29
23
25
P2.5
A13
I/O
27
30
24
26
P2.6
A14
I/O
RESET: RST pin is a Schmitt trigger input pin for
hardware device reset. A high on this pin for two
machine-cycles while the system clock is running
will reset the device. RST pin has an internal pulldown resistor allowing power-on reset by simply
connecting an external capacitor to VDD.
PORT0: Port 0 is an 8-bit open-drain port by default. Via setting P0UP (P0OR.0), P0 will switch as
weakly pulled up internally.
P0 has an alternative function as AD[7:0] while external memory accessing. During the external
memory access, P0 will output high will be internal
strong pulled-up rather than weak pull-up in order to
drive out high byte address for external devices.
PORT1: Port 1 is an 8-bit quasi bi-directional I/O
port. Its multifunction pins are for T2, T2EX, PWM0PWM4, SS , MOSI, MISO, and SPCLK.
I/O
I/O
- 11 -
PORT2: Port 2 is an 8-bit quasi bi-directional I/O
port. It has an alternative function as A[15:8] while
external memory accessing. During the external
memory access, P2 will output high will be internal
strong pulled-up rather than weak pull-up in order to
drive out high byte address for external devices.
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Table 4–1. Pin Description
Pin number
DIP
Alternate Function
PQFP
PLCC
LQFP
TQFP
Type
Symbol
[1
Description
]
1
2
28
31
25
27
P2.7
A15
I/O
10
11
5
5
P3.0
RXD
I/O
11
13
7
7
P3.1
TXD
I/O
12
14
8
8
P3.2
INT0
I/O
13
15
9
9
P3.3
INT1
I/O
14
16
10
10
P3.4
T0
I/O
15
17
11
11
P3.5
T1
I/O
16
18
12
13
P3.6
WR
I/O
17
19
13
14
P3.7
RD
I/O
-
23
17
18
P4.0
I/O
-
34
28
30
P4.1
I/O
-
1
39
42
P4.2
INT3
I/O
-
12
6
6
P4.3
INT2
I/O
-
-
-
48
P4.4
I/O
-
-
-
12
P4.5
I/O
-
-
-
24
P4.6
I/O
-
-
-
36
P4.7
I/O
PORT3: Port 3 is an 8-bit quasi bi-directional I/O
port. Its multifunction pins are for RXD, TXD, INT0 ,
INT1 , T0, T1, WR , and RD .
[3]
PORT4 : Port 4 is an 8-bit quasi bi-directional I/O
port. It also possesses bit-addressable feature as
P0-P3. P4.2 and P4.3 are alternative function pins
of INT3 and INT2 .
[1] I/O type description. I: input, O: output, I/O: quasi bi-direction, D: open-drain, P: power pins, ST: Schmitt trigger.
[2] While switching to 6T mode, ALE will run at 1/3 of Fosc.
[3] A full 8-bit P4 is just on LQPF-48 package. PLCC-44, PQFP-44, and TQFP-44 just have low nibble 4 bits of P4. DIP-40
does not have this additional P4.
- 12 -
The application circuit is shown below. The user is recommended follow the circuit enclosed by gray blocks to
achieve the most stable and reliable operation of MCU especially in a noisy power environment for a healthy
EMS immunity. If internal RC oscillator is used as the system clock, a 0.1μF capacitor should be added to gain
a precise RC frequency.
10μF
RST
VDD
VDD
0.1μF
10kΩ
C1
0.1μF
EA
XTAL1
10μF
as close to MCU
as possible
R
XTAL2
C2
VSS
GND
N78E517A
as close to the
power source
as possible
Figure 4–5. Application Circuit for Execution of Internal Program Code with External Crystal
Crystal Frequency
R
C1
4MHz-33MHz
Without
33MHZ-40MHz
5kΩ-10kΩ
C2
Depend on crystal
specifications
10μF
RST
VDD
VDD
0.1μF
10kΩ
0.1μF
EA
XTAL1
as close to MCU
as possible
0.1μF
XTAL2
as close to MCU
as possible
10μF
VSS
GND
N78E517A
as close to the
power source
as possible
Figure 4–6. Application Circuit for Execution of Internal Program Code with Internal RC Oscillator
- 13 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
5. MEMORY ORGANIZATION
A standard 8051 based MCU divides the memory into two different sections, the Program Memory and the Data Memory. The Program Memory is used to store the instruction codes, whereas the Data Memory is used to
store data or variations during the program execution.
Data Memory occupies a separate address space from Program Memory. In N78E517A, there are 256 bytes of
internal scratch-pad RAM and up to 64k bytes of memory space for external Data Memory. The MCU generates the 16-bit or 8-bit addresses, read and write strobe signals ( RD and WR , respectively) during external
Data Memory access. For many applications which need more internal RAM, N78E517A possesses on-chip 1k
bytes of RAM (called XRAM) accessed by MOVX instruction.
The whole embedded flash is divided into 4 banks, APROM for storage of user‟s program code, Data Flash for
parameter data storage, LDROM for ISP program and CONFIG bytes. Each bank is accumulated page by
page and the page size is 256 bytes. The flash control unit supports Page Erase, Byte Program, and Byte
Read modes. The external writer tools though specific I/O pins or the internal ISP (In System Programming)
function can both performs these modes.
5.1 Internal Program Memory
Program Memory is the one, which stores the program codes to execute, as shown in Figure 5–1. While EA
pin is pulled high and after any reset, the CPU begins execution from location 0000H where should be the
starting point of the user‟s application code. To service the interrupts, the interrupt service locations (called interrupt vectors) should be located in the Program Memory. Each interrupt is assigned with a fixed location in
the Program Memory. The interrupt causes the CPU to jump to that location with where it commences execution of the interrupt service routine (ISR). External Interrupt 0, for example, is assigned to location 0003H. If
External Interrupt 0 is going to be used, its service routine must begin at location 0003H. If the interrupt is not
going to be used, its service location is available as general purpose Program Memory.
The interrupt service locations are spaced at an interval of 8 bytes: 0003H for External Interrupt 0, 000BH for
Timer 0, 0013H for External Interrupt 1, 001BH for Timer 1, etc. If an interrupt service routine is short enough
(as is often the case in control applications), it can reside entirely within that 8-byte interval. However longer
service routines should use a JMP instruction to skip over subsequent interrupt locations if other interrupts are
in use.
N78E517A provides two internal Program Memory bank APROM and LDROM. Although they both behave the
same as the standard 8051 Program Memory, they play different rules according to their ROM size. The
APROM on N78E517A can be 64k-byte size maximum. The user‟s main program code is normally put inside.
- 14 -
All instructions are fetched for execution from this area. The MOVC instruction can also read this flash memory
region.
N78E517A supports the other individual Program Memory bank called LDROM besides APROM. The main
function of LDROM is to store the ISP application program. User may develop the ISP in LDROM for updating
APROM content. The program in APROM can also re-program LDROM. For ISP details and configuration bit
setting related with APROM and LDROM, see Section 18. “IN SYSTEM PROGRAMMING (ISP)” on page 92.
Note that because APROM and LDROM are hardware individual blocks, consequently if CPU reboots from
LDROM, CPU will automatically re-vectors Program Counter 0000H to the LDROM start address. Therefore,
CPU accounts the LDROM as an independent Program Memory and all interrupt vectors are independent from
APROM.
FFFFH
FFFFH
FFFFH
[3]
[1]
0000H
APROM
09FFH
0000H
[3]
LDROM
Internal Program Memory
EA = 1, BS = 0[2]
EA = 1, BS = 1
0000H
External Program Memory
EA = 0
[1] The address is [SHBDA, 00H] - 1. It is valid while DFEN (CONFIG0.0) is 0.
[2] EA is the state of EA pin after power-on reset. BS is bit 1 of CHPCON.
[3] While execution beyond the top boundary of internal Program Memory, CPU will switch to
external Program Memory to continue.
Figure 5–1. N78E517A Program Memory Structure
- 15 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
5.2 External Program Memory
N78E517A is a 16-bit address-width CPU. It can address 64k-byte program code. Besides the internal Program Memory, the external additional Program Memory is also can be used. The external program addressing
will be executed under cases below,
1. The PC (Program Counter) value is beyond the boundary size address of APROM or LDROM while EA pin
is pulled high during power on. The CPU will continue to fetch the external Program Memory.
2. While EA pin is pulled low during power on period, The CPU will run totally 64k-byte code externally.
While the external mode is running, the P0 and P2 will produce address and data signals to fetching external
Program Memory. In this case, P0 and P2 cannot be general purpose I/O anymore. PSEN will also toggle out
to strobe the external Program Memory. For the hardware circuit for external program execution, see Figure 5–
2. Program Memory Interface.
For security EA pin state will be locked after power on. The user cannot switch the program running internally
or externally by EA after power on. The other design for data security is MOVC lock enable (MOVCL,
CONFIG0.2). While this bit is set 0, The external Program Memory code is inhibited to read internal APROM or
LDROM contents through MOVC instruction.
P0
N78E517A
8
External
Program
Memory
Data[7:0]
8
P0
LATCH
ALE
Address[7:0]
8
P2
Address[15:8]
PSEN
OE
EA
P0
Figure 5–2. Program Memory Interface
- 16 -
5.3 Internal Data Memory
Figure 5–3 shows the internal and external Data Memory spaces available on N78E517A. Internal Data
Memory can be divided into three blocks. They are the lower 128 bytes of RAM, the upper 128 bytes of RAM,
and the 128 bytes of SFR space. Internal Data Memory addresses are always 8-bit wide, which implies an address space of only 256 bytes. Direct addressing higher than 7FH will access the special function registers
(SFRs) space and indirect addressing higher than 7FH will access the upper 128 bytes of RAM. Although the
SFR space and the upper 128 bytes of RAM share the same logic address, 80H through FFH, actually they are
physically separate entities. Direct addressing to distinguish with the higher 128 bytes of RAM can only access
these SFRs. Sixteen addresses in SFR space are either byte-addressable or bit-addressable. The bitaddressable SFRs are those whose addresses end in 0H or 8H.
The lower 128 bytes of internal RAM are present in all 8051 devices. The lowest 32 bytes are grouped into 4
banks of 8 registers. Program instructions call these registers as R0 through R7. Two bits RS0 and RS1 in the
Program Status Word (PSW[3:4]) select which Register Bank is used. It benefits more efficiency of code
space, since register instructions are shorter than instructions that use direct addressing. The next 16 bytes
above the Register Banks (byte-address 20H through 2FH) form a block of bit-addressable memory space (bitaddress 00H through 7FH). The 8051 instruction set includes a wide selection of single-bit instructions, and the
128 bits in this area can be directly addressed by these instructions. The bit addresses in this area are 00H
through 7FH.
All bytes in the lower 128-byte space can be accessed by either direct or indirect addressing. Indirect addressing can only access the upper 128.
Another application implemented with the whole block of internal 256-byte RAM is for the stack. This area is
selected by the Stack Pointer (SP), which stores the address of the top of the stack. Whenever a JMP, CALL
or interrupt is invoked, the return address is placed on the stack. There is no restriction as to where the stack
can begin in the RAM. By default however, the Stack Pointer contains 07H at reset. The user can then change
this to any value desired. The SP will point to the last used value. Therefore, the SP will be incremented and
then address saved onto the stack. Conversely, while popping from the stack the contents will be read first,
and then the SP is decreased.
- 17 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
00H
FFFFH
FFH
80H
7FH
00H
Upper 128 bytes
internal RAM
(indirect addressing)
SFR
(direct addressing)
[2]
3FFH
Lower 128 bytes
internal RAM
(direct or indirect
addressing)
000H
1k bytes
Auxiliary RAM
(XRAMEN[1]= 1)
External
Data Memory
(XRAMEN = 0)
0000H
[1] XRAMEN is bit 4 of CHPCON. XRAM is enabled after
any reset.
[2] If XRAMEN is 1 yet the address over 3FFH, CPU will
use external data memory above 400H.
Figure 5–3. N78E517A Data Memory Structure
FFH FFH
Indirect Accessing RAM
80H
7FH
Direct or Indirect Accessing RAM
30H
2FH
2EH
2DH
2CH
2BH
2AH
29H
28H
27H
26H
25H
24H
23H
22H
21H
20H
1FH
18H
17H
10H
0FH
08H
07H
7F
77
6F
67
5F
57
4F
47
3F
37
2F
27
1F
17
0F
07
7E
76
6E
66
5E
56
4E
46
3E
36
2E
26
1E
16
0E
06
7D
75
6D
65
5D
55
4D
45
3D
35
2D
25
1D
15
0D
05
7C
74
6C
64
5C
54
4C
44
3C
34
2C
24
1C
14
0C
04
7B
73
6B
63
5B
53
4B
43
3B
33
2B
23
1B
13
0B
03
7A
72
6A
62
5A
52
4A
42
3A
32
2A
22
1A
12
0A
02
79
71
69
61
59
51
49
41
39
31
29
21
19
11
09
01
78
70
68
60
58
50
48
40
38
30
28
20
18
10
08
00
Register Bank 3
Register Bank 2
Register Bank 1
Register Bank 0
00H
00H
Figure 5–4. 256 bytes Internal RAM Addressing
- 18 -
5.4 On-chip XRAM
N78E517A provides additional on-chip auxiliary RAM called XRAM to enlarge RAM space. The 1024 bytes of
XRAM (000H to 3FFH) are indirectly accessed by move external instruction MOVX. For details, see Section 8.
“AUXILIARY RAM (XRAM)” on page 30.
5.5 External Data Memory
Access to external Data Memory can use either a 16-bit address (using „MOVX @DPTR‟) or an 8-bit address
(using „MOVX @Ri‟, i = 0 or 1). For another 1k-byte XRAM exists, remember the bit XRAMEN (CHPCON.4)
should be cleared as logic 0 in order to access the range of 000H to 3FFH address of the external Data
Memory.
16-bit addresses are often used to access up to 64k bytes of external RAM. Whenever a 16-bit address is
used, P0, P2, P3.7 and P3.6 serve as the low byte address/data, the high byte address, RD strobe and WR
strobe signals respectively. Meanwhile the pins listed above cannot be used as general purpose I/O during
external Data Memory access.
8-bit addresses are often used in conjunction with one or more other I/O lines to page the RAM. For example, if
a 1k-byte external RAM is used, Port 0 serves as a multiplexed address/data bus to the RAM, and 2 pins of
Port 2 are used to page the RAM. The CPU generates RD and WR (alternate functions of P3.7 and P3.6) to
strobe the memory. In 8-bit addressing mode, P2 pins other than the two pins for RAM paging are free for general purpose I/O usage. It facilitates P2 application. Of course, the user may use any other I/O lines instead of
P2 to page the RAM.
In all cases, the low byte of the address is time-multiplexed with the data byte on Port 0. ALE (Address Latch
Enable) should be used to capture the address byte into an external latch. The address byte is valid at the
negative transition of ALE. Then, in a write cycle, the data byte to be written appears on Port 0 just before WR
is activated, and remains there until after WR is deactivated. In a read cycle, the incoming byte is accepted at
Port 0 just before the read strobe is deactivated. During any access to external memory, the CPU writes 0FFH
to the Port 0 latch (P0 in SFRs), thus obliterating whatever information the Port 0 SFR may have been holding.
- 19 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
P0
N78E517A
8
External
Data
Memory
Data[7:0]
8
LATCH
P0
ALE
Address[7:0]
8
P2
Address[15:8]
RD
OE
WR
WE
Figure 5–5. Data Memory Interface
5.6 On-chip Non-volatile Data Flash
N78E517A additionally has Data Flash. The Data Flash is non-volatile so that it remains its content even after
the power is off. Therefore, in general application the user can write or read data which rules as parameters or
constants. Be aware of Data Flash writing endurance of 10,000 cycles. By the software path, the Data Flash
can be accessed only through ISP mode. Note that the erasing or writing of Data Flash should not operates
under VDD 3.0V for ISP limitation. For Data Flash accessing with ISP, please see Section 18. “IN SYSTEM
PROGRAMMING (ISP)” on page 92 for details. For the design for security, ISP is invalid while external Program Memory executes. The Data Flash, therefore, cannot be accessed with external memory code. Of course
the Data Flash can be accessed via hardware with parallel Programmer/Writer.
The Data Flash size is software adjustable on N78E517A by updating the content of SHBDA. SHBDA[7:0] represents the high byte of 16-bit Data Flash start address and the low byte are hardware set to 00H. The value of
SHBDA is loaded from the content of CONFIG1 (CHBDA) after all resets. The application program can dynamically adjust the Data Flash size by resetting SHBDA value. Once the Data Flash size is changed the APROM
size is changed accordingly. SHBDA has time access protect while a write to SHBDA is required. Be aware
that if CHBDA is 00H, the Data Flash size will be 64k bytes and there will be no APROM. CPU will execute
codes in the external Program Memory.
The CONFIG bit DFEN (CONFIG0.0) should be programmed as a 0 before access the Data Flash block. If
DFEN remains its unprogrammed value 1, APROM will occupy whole 64k-byte block.
- 20 -
FFFFH
Data Flash
[1]
APROM
0000H
[1] The address is [SHBDA, 00H]
while DFEN (CONFIG0.0) is 0.
Figure 5–6. N78E517A Data Flash
CONFIG0
7
CBS
r/w
6
-
5
-
4
-
3
-
2
1
0
MOVCL
LOCK
DFEN
r/w
r/w
r/w
unprogrammed value: 1111 1111b
Bit
Name
Description
0
DFEN
Data Flash enable.
1 = There is no Data Flash space. The APROM size is 64k-byte.
0 = Data Flash exists. The Data Flash and APROM share 64k bytes depending on
SHBDA setting.
CONFIG1
7
6
5
4
3
CHBDA[7:0][1]
r/w
2
1
0
unprogrammed value: 1111 1111b
Bit
Name
Description
CONFIG high byte of Data Flash starting address.
This byte is valid only when DFEN (CONFIG0.0) being 0 condition. It is used to
determine the starting address of the Data Flash.
[1] Note that there will be no APROM if setting CHBDA 00H. CPU will execute codes in the external Program Memory.
7:0
CHBDA[7:0]
- 21 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
SHBDA – SFR High Byte of Data Flash Starting Address (TA protected)
7
6
5
4
3
2
1
0
[1]
SHBDA[7:0]
r/w
Address: 9CH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
SFR high byte of Data Flash starting address.
This byte is valid only when DFEN (CONFIG0.0) being 0 condition. It is used
to dynamic adjust the starting address of the Data Flash when the application
program is executing.
[1] SHBDA is loaded from CONFIG1 after all resets.
7:0
SHBDA[7:0]
- 22 -
6. SPECIAL FUNCTION REGISTER (SFR)
The N78E517A uses Special Function Registers (SFRs) to control and monitor peripherals and their modes.
The SFRs reside in the register locations 80-FFH and are accessed by direct addressing only. Some of the
SFRs are bit-addressable. It is very useful in cases where users would like to modify a particular bit directly
without changing other bits. Those which are bit-addressable SFRs end their addresses as 0H or 8H.
N78E517A contains all the SFRs presenting in the standard 8051. However some additional SFRs are built in.
Therefore, some of unused bytes in the original 8051 have been given new functions. The SFRs is listed below.
Table 6–1. N78E517A Special Function Registers Mapping
F8
-
-
-
-
-
-
-
-
FF
F0
B
-
-
SPCR
SPSR
SPDR
-
-
F7
E8
-
-
-
-
-
-
-
-
EF
E0
ACC
-
-
-
-
-
-
-
E7
D8
P4
PWMP
PWM0
PWM1
PWMCON0
PWM2
PWM3
-
DF
D0
PSW
-
-
-
-
-
-
-
D7
C8
T2CON
T2MOD
RCAP2L
RCAP2H
TL2
TH2
PWMCON1
PWM4
CF
C0
XICON
-
-
-
-
-
-
TA
C7
B8
IP
-
IPH
EIPH
EIP
EIE
-
-
BF
B0
P3
-
-
-
-
-
-
-
B7
A8
IE
-
WDCON
PDCON
PMC
-
ISPFD
ISPCN
AF
A0
P2
XRAMAH
-
-
ISPTRG
-
ISPAL
ISPAH
A7
98
SCON
SBUF
-
-
SHBDA
-
-
CHPCON
9F
90
P1
-
-
-
-
-
RSR
-
97
88
TCON
TMOD
TL0
TL1
TH0
TH1
AUXR
-
8F
80
P0
SP
DPL
DPH
-
-
P0OR
PCON
87
In Bold
-
bit-addressable
reserved
Note that the reserved SFR addresses must be kept in their own initial states. Users should never
change their values.
- 23 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Table 6–2. N78E517A SFR Description and Reset Values
Symbol
Definition
Address
F5H
F4H
F3H
F0H
E0H
DEH
DDH
DCH
DBH
DAH
D9H
P4
Port 4
D8H
PSW
Program status word
D0H
PWM4
PWMCON1
TH2
TL2
CFH
CEH
CDH
CCH
CBH
0000 0000b
T2MOD
PWM4 duty
PWM control 1
Timer 2 high byte
Timer 2 low byte
Timer 2 reload/capture
high byte
Timer 2 reload/capture
low byte
Timer 2 mode
Reset Value
0000 0000b
SPIF
WCOL
SPIOVF
MODF DISMODF
0000 0000b
SSOE
SPIEN
LSBFE
MSTR
CPOL
CPHA
SPR1
SPR0 0 0 0 0 0 0 0 0 b
(F7)
(F6)
(F5)
(F4)
(F3)
(F2)
(F1)
(F0)
0000 0000b
(E7)
(E6)
(E5)
(E4)
(E3)
(E2)
(E1)
(E0)
0000 0000b
0000 0000b
0000 0000b
PWM3OE PWM2OE PWM3EN PWM2EN PWM1OE PWM0OE PWM1EN PWM0EN 0 0 0 0 0 0 0 0 b
0000 0000b
0000 0000b
0000 0000b
(DF)
(DE)
(DD)
(DC)
(DB)
(DA)
(D9)
(D8)
1111 1111b
INT 3
INT 2
(D7)
(D6)
(D5)
(D4)
(D3)
(D2)
(D1)
(D0)
0000 0000b
CY
AC
F0
RS1
RS0
OV
F1
P
0000 0000b
PWM4OE
PWM4EN 0 0 0 0 0 0 0 0 b
0000 0000b
0000 0000b
T2CON
Timer 2 control
C8H
TA
Timed access protection
C7H
RCAP2L
XICON
External interrupt control
CAH
(CE)
(CD)
(CC)
(CB)
(CA)
T2OE
(C9)
(C8)
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C / T2
CP / RL 2
C0H
(C7)
PX3
(C6)
EX3
(C4)
IE3
(C4)
IT3
(C3)
PX2
(C2)
EX2
(C1)
IE2
(C0)
1IT2
0000 0000b
BDH
-
-
-
-
-
EBOD
EPDT
ESPI
0000 0000b
BCH
-
-
-
-
-
PBOV
PPDT
PSPI
0000 0000b
C9H
IPH
IP
Interrupt priority
B8H
P3
Port 3
B0H
ISPCN
ISPFD
ISP flash control
ISP flash data
AFH
AEH
EIP
EIPH
0000 0000b
(CF)
Extensive interrupt enable
Extensive interrupt priority
Extensive interrupt priority high
Interrupt priority high
EIE
LSB
[2]
SPI data
SPI status
SPI control
B register
Accumulator
PWM3 duty
PWM2 duty
PWM control 0
PWM1 duty
PWM0 duty
PWM period
RCAP2H
MSB
[1]
SPDR
SPSR
SPCR
B
ACC
PWM3
PWM2
PWMCON0
PWM1
PWM0
PWMP
0000 0000b
0000 0000b
0000 0000b
BBH
-
-
-
-
-
PBODH
PPDTH
PSPIH
0000 0000b
BAH
PX3H
(BF)
(B7)
PX2H
(BE)
(B6)
PT2H
(BD)
PT2
(B5)
PSH
(BC)
PS
(B4)
PT1H
(BB)
PT1
(B3)
PX1H
(BA)
PX1
(B2)
PT0H
(B9)
PT0
(B1)
PX0H
(B8)
PX0
(B0)
0000 0000b
RD
ISPA17
WR
ISPA16
T1
FOEN
T0
FCEN
INT1
FCTRL3
INT 0
FCTRL2
TXD
FCTRL1
0000 0000b
1111 1111b
RXD
FCTRL0 0 0 0 0 0 0 0 0 b
0000 0000b
[6]
PMC
[3]
PDCON
Power monitoring control
ACH
BODEN
-
-
BORST
Power Down waking-up
timer control
ABH
PDTEN
PDTCK
PDTF
-
[4]
BOF
-
LPBOD
-
PPS2
PPS1
BOS
[5]
Power-on ,
X X X X X 0 0 Xb
Brown-out,
XXXX 100Xb
Others,
XXXX 000Xb
PPS0
0000 0000b
[6]
Watchdog Timer control
AAH
WDTEN
WDCLR
-
WIDPD
WDTRF
WPS2
WPS1
WPS0
Power-on ,
X000 0000b
Watchdog,
X00U 1U U U b
Others,
X00U UUUUb
IE
Interrupt enable
A8H
(AF)
EA
(AE)
-
(AD)
ET2
(AC)
ES
(AB)
ET1
(AA)
EX1
(A9)
ET0
(A8)
EX0
0000 0000b
ISPAH
ISPAL
ISP address high byte
ISP address low byte
ISP trigger
Auxiliary RAM address
high byte
A7H
A6H
A4H
WDCON
ISPTRG
[3]
[3]
XRAMAH
P2
Port 2
-
-
-
-
-
-
A1H
-
-
-
-
-
-
A0H
(A7)
A15
(A6)
A14
(A5)
A13
(A4)
A12
(A3)
A11
(A2)
A10
- 24 -
-
ISPGO
0000 0000b
0000 0000b
0000 0000b
XRAMAH.1 XRAMAH.0 0 0 0 0 0 0 0 0 b
(A1)
A9
(A0)
A8
1111 1111b
Table 6–2. N78E517A SFR Description and Reset Values
Symbol
Definition
Address
MSB
LSB
[1]
[2]
Reset Value
[6]
CHPCON
SHBDA
[3]
[3]
SBUF
SCON
Chip control
SFR high byte of Data
Flash starting address
Serial buffer
Serial control
9FH
SWRST
ISPF
LDUEN
XRAMEN
-
-
BS
ISPEN
[6]
9CH
XXXX XXXXb
99H
98H
RSR
Reset status register
96H
P1
Port 1
90H
Software ,
0001 00U0b
Others,
0001 00X0b
0000 0000b
(9F)
SM0
(9E)
SM1
(9D)
SM2
(9C)
REN
(9B)
TB8
(9A)
RB8
(99)
TI
(98)
RI
0000 0000b
Power-on,
0000 0000b
Brown-out,
0000 010Ub
Software,
0000 0U01b
Others,
0000 0U0Ub
-
-
-
-
-
BORF
-
SWRF
(97)
PWM4
(96)
PWM3
(95)
PWM2
(94)
PWM1
(93)
PWM0
(92)
(91)
T2EX
(90)
T2
SPCLK
-
MISO
-
MOSI
-
SS
-
-
-
-
GATE
(8F)
TF1
C/T
(8E)
TR1
M1
(8D)
TF0
M0
(8C)
TR0
GATE
(8B)
IE1
C/T
(8A)
IT1
M1
(89)
IE0
AUXR
TH1
TH0
TL1
TL0
TMOD
Auxiliary register
Timer 1 high byte
Timer 0 high byte
Timer 1 low byte
Timer 0 low byte
Timer 0 and 1 mode
8EH
8DH
8CH
8BH
8AH
89H
TCON
Timer 0 and 1control
88H
PCON
Power control
87H
SMOD
-
-
POF
GF1
GF0
PD
P0OR
DPH
DPL
SP
P0 option register
Data pointer high byte
Data pointer low byte
Stack pointer
86H
83H
82H
81H
-
-
-
-
-
-
-
P0
Port 0
80H
(87)
A7
(86)
A6
(85)
A5
(84)
A4
(83)
A3
(82)
A2
(81)
A1
1111 1111b
ALEOFF 0 0 0 0 0 0 0 0 b
0000 0000b
0000 0000b
0000 0000b
0000 0000b
M0
0000 0000b
(88)
0000 0000b
IT0
Power-on,
0001 0000b
IDL
Others,
000U 0000b
P0UP 0 0 0 0 0 0 0 0 b
0000 0000b
0000 0000b
0000 0111b
(80)
1111 1111b
A0
[1] ( ) item means the bit address in bit-addressable SFRs.
[2] Reset value symbol description. 0: logic 0, 1: logic 1, U: unchanged, X: see [4] - [6].
[3] These SFRs have TA protected writing.
[4] BOF has different power-on reset value according to CBODEN (CONFIG2.7) and CBORST (CONFIG2.4). See Table
21–1. BOF Reset Value.
[5] BOS is a read-only flag decided by VDD level while Brown-out detection is enabled.
[6] These SFRs have bits which are initialized after specified reset by loading certain bits in CONFIG bytes. See Section
24. “CONFIG BYTES” on page 117 for details.
Note that bits marked in “-“ must be kept in their own initial states. Users should never change their
values.
- 25 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
7. GENERAL 80C51 SYSTEM CONTROL
A or ACC – Accumulator (bit-addressable)
7
6
5
4
ACC.7
ACC.6
ACC.5
ACC.4
r/w
r/w
r/w
r/w
Address: E0H
3
ACC.3
r/w
2
ACC.2
r/w
1
0
ACC.1
ACC.0
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7:0
ACC[7:0]
Accumulator.
The A or ACC register is the standard 8051 accumulator for arithmetic operation.
B – B Register (bit-addressable)
7
6
5
B.7
B.6
B.5
r/w
r/w
r/w
Address: F0H
4
B.4
r/w
3
B.3
r/w
2
B.2
r/w
1
0
B.1
B.0
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7:0
B[7:0]
B register.
The B register is the other accumulator of the standard 8051. It is used mainly for
MUL and DIV operations.
SP – Stack Pointer
7
6
5
4
3
2
1
0
SP[7:0]
r/w
Address: 81H
reset value: 0000 0111b
Bit
Name
Description
7:0
SP[7:0]
Stack pointer.
The Stack Pointer stores the scratch-pad RAM address where the stack begins. It
is incremented before data is stored during PUSH or CALL instructions. Note that
the default value of SP is 07H. It causes the stack to begin at location 08H.
DPL – Data Pointer Low Byte
7
6
5
4
3
2
1
0
DPL[7:0]
r/w
Address: 82H
reset value: 0000 0000b
Bit
Name
Description
7:0
DPL[7:0]
Data pointer low byte.
This is the low byte of the standard 8051 16-bit data pointer. DPL combined with
DPH serve as a 16-bit data pointer DPTR to address non-scratch-pad memory or
Program Memory.
- 26 -
DPH – Data Pointer High Byte
7
6
5
4
3
2
1
0
DPH[7:0]
r/w
Address: 83H
reset value: 0000 0000b
Bit
Name
Description
7:0
DPH[7:0]
Data pointer high byte.
This is the high byte of the standard 8051 16-bit data pointer. DPH combined with
DPL serve as a 16-bit data pointer DPTR to address non-scratch-pad memory or
Program Memory.
PSW – Program Status Word (bit-addressable)
7
6
5
4
CY
AC
F0
RS1
r/w
r/w
r/w
r/w
Address: D0H
3
RS0
r/w
2
OV
r/w
1
0
F1
P
r/w
r
reset value: 0000 0000b
Bit
Name
Description
7
CY
Carry flag.
For a adding or subtracting operation, CY will be set when the previous operation
resulted in a carry-out from or a borrow-in to the Most Significant bit; otherwise, it
is cleared.
If the previous operation is MUL or DIV, CY is always 0.
CY is affected by DA A instruction which indicates that if the original BCD sum is
greater than 100.
For a CJNE branch, CY will be set if the first unsigned integer value is less than
the second one. Otherwise, CY will be cleared.
6
AC
Auxiliary carry.
Set when the previous operation resulted in a carry-out from or a borrow-in to the
th
4 bit of the low order nibble; otherwise, it is cleared.
5
F0
User flag 0.
The general purpose flag that can be set or cleared by the user.
4
RS1
3
RS0
Register Bank selecting bits.
These two bits select one of four banks in which R0-R7 locate.
RS1 RS0
Register Bank
RAM Address
0
0
0
00-07H
0
1
1
08-0FH
1
0
2
10-17H
1
1
3
18-1FH
- 27 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Bit
Name
Description
2
OV
Overflow flag.
OV is used for a signed character operands. For a ADD or ADDC instruction, OV
will be set if there is a carry out of bit 6 but not out of bit 7, or a carry out of bit 7
but not bit 6. Otherwise, OV is cleared. OV indicates a negative number produced
as the sum of two positive operands or a positive sum from two negative operands. For a SUBB, OV is set if a borrow is needed into bit6 but not into bit 7, or
into bit7 but not bit 6. Otherwise, OV is cleared. OV indicates a negative number
produced when a negative value is subtracted from a positive value, or a positive
result when a positive number is subtracted from a negative number.
For a MUL, if the product is greater than 255 (00FFH), OV will be set. Otherwise,
it is cleared.
For a DIV, it is normally 0. However, if B had originally contained 00H, the values
returned in A and B will be undefined. Meanwhile, the OV will be set.
1
F1
User flag 1.
The general purpose flag that can be set or cleared by the user via software.
0
P
Parity flag.
Set to 1 to indicate an odd number of ones in the accumulator. Cleared for an
even number of ones. It performs even parity check.
Table 7–1. Instructions that affect flag settings
Instruction
ADD
CY
[1]
X
OV
AC
Instruction
CY
X
X
CLR C
0
ADDC
X
X
X
CPL C
X
SUBB
X
X
X
ANL C, bit
X
MUL
0
X
ANL C, /bit
X
DIV
0
X
ORL C, bit
X
DA A
X
ORL C, /bit
X
RRC A
X
MOV C, bit
X
RLC A
X
CJNE
X
SETB C
1
[1] X indicates the modification depends on the result of the instruction.
- 28 -
OV
AC
PCON – Power Control
7
6
SMOD
r/w
Address: 87H
5
-
4
3
2
1
0
POF
GF1
GF0
PD
IDL
r/w
r/w
r/w
r/w
r/w
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
3
GF1
General purpose flag 1.
The general purpose flag that can be set or cleared by the user.
2
GF0
General purpose flag 0.
The general purpose flag that can be set or cleared by the user.
- 29 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
8. AUXILIARY RAM (XRAM)
N78E517A provides additional on-chip 1k-byte RAM called XRAM to enlarge the RAM space. It occupies the
address space from 000H through 3FFH. The XRAM is enabled after all resets. The 1024 bytes of XRAM are
indirectly accessed by move external instruction MOVX @DPTR or MOVX @Ri along with XRAMAH. (If XRAM
is enabled, MOVX @Ri cannot be used to access external RAM anymore.) This block of XRAM shares the
same logic address of 000H through 3FFH with the external RAM. A DPTR value given larger than 03FFH will
map to the external RAM no matter of the value of bit XRAMEN (CHPCON.4). If the user would like to access
contents within 000H to 3FFH address of the off-chip external XRAM, the XRAMEN bit should be cleared as
logic 0. (Note that CHPCON is a TA writing protected SFR.) When the XRAM is accessed, the address fetching
signal will not emit via P0, P2, WR , and RD . Note that the stack pointer cannot locate in any part of XRAM.
CHPCON – Chip Control (TA protected)
7
6
5
4
3
2
1
0
SWRST
ISPF
LDUEN
XRAMEN
BS
ISPEN
w
r/w
r/w
r/w
r/w
r/w
Address: 9FH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
4
XRAMEN
XRAMAH – XRAM
7
Address: A1H
Description
XRAM enable.
0 = Disable on-chip XRAM.
1 = Enable on-chip XRAM. (The default value after all resets.)
Address High Byte
6
5
-
Bit
Name
7:2
-
1:0
XRAMAH[1:0]
4
-
3
-
2
-
1
0
XRAMAH.1 XRAMAH.0
r/w
r/w
reset value: 0000 0000b
Description
Reserved.
XRAM address high byte.
To set the XRAM high byte address. This setting works along with MOV @Ri
instructions. The demo codes are listed below.
XRAM demo code:
MOV
MOV
MOV
MOVX
XRAMAH,#01H
R0,#23H
A,#5AH
@R0,A
;write #5AH to XRAM with address @0123H.
MOV
MOV
MOVX
XRAMAH,#01H
R0,#23H
A,@R0
;read from XRAM with address @0123H.
- 30 -
MOV
MOV
MOVX
DPTR,#0123H
A,#5BH
@DPTR,A
;write #5BH to XRAM with address @0123H.
MOV
MOVX
DPTR,#0123H
A,@DPTR
;read from XRAM with address @0123H.
- 31 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
9. I/O PORT STRUCTURE AND OPERATION
N78E517A has maximum five 8-bit width, bit-addressable ports P0-P4. The configuration of P1-P4 is the quasi
bi-directional I/O. This type rules as both input and output. When the port outputs a logic high, it is weakly driven, allowing an external device to pull the pin low. When the pin is pulled low, it is driven strongly and able to
sink a large current. In the quasi bi-directional I/O structure, there are three pull-up transistors. Each of them
serves different purposes. One of these pull-ups, called the “very weak” pull-up, is turned on whenever the port
latch contains a logic 1. The “very weak” pull-up sources a very small current that will pull the pin high if it is left
floating.
A second pull-up, called the “weak” pull-up, is turned on when the outside port pin itself is at a logic 1 level.
This pull-up provides the primary source current for a quasi bi-directional pin that is outputting a 1. If a pin that
has a logic 1 on it is pulled low by an external device, the “weak” pull-up turns off, and only the “very weak”
pull-up remains on. In order to pull the pin low under these conditions, the external device has to sink enough
current (larger than ITL) to overcome the “weak” pull-up and make the voltage on the port pin below its input
threshold (lower than VIL).
The third pull-up is the “strong” pull-up. This pull-up is used to speed up low-to-high transitions on a quasi bidirectional port pin when the port latch changes from a logic 0 to a logic 1. When this occurs, the strong pull-up
turns on for two-peripheral-clock time in order to pull the port pin high quickly. Then it turns off and “weak”: pullup continues remaining the port pin high. The quasi bi-directional port structure is shown below.
VDD
2-peripheralclock delay
P
Strong
P
Very
Weak
P
Weak
Port Pin
Port Latch
N
Input
Figure 9–1. Quasi Bi-direction I/O Structure
The default configuration of P0 is open-drain structure. To serve as an I/O port the external pull-up resistor is
always necessary. N78E517A also provide an internal P0 pull-up resistors for each pins. Via setting P0UP
(P0OR.0) P0 will switch on its weak pull-up internally and behave the same as the quasi bi-directional I/O pins.
- 32 -
P0 and P2 also serve as address/data bus when external memory is running or is accessed by MOVC or
MOVX instruction. In these cases, it has strong pull-up and pull-down. In this application, there is no need of
any external pull-up resistor. While external mode execution, P0 and P2 cannot be used as general purpose
I/O anymore.
In standard 8051 instruction set, one kind of instructions, read-modify-write instructions, should be specially
taken care of. Instead of the normal instructions, the read-modify-write instructions read the internal port latch
(Px in SFRs) rather than the external port pin state. This kind of instructions read the port SFR value, modify it
and write back to the port SFR. Read-modify-write instructions are listed as follows:
Instruction
Description
ANL
Logical AND. (ANL Px,A and ANL Px,direct)
ORL
Logical OR. (ORL Px,A and ORL Px,direct)
XRL
Logical exclusive OR. (XRL Px,A and XRL Px,direct)
JBC
Jump if bit = 1 and clear it. (JBC Px.y,LABEL)
CPL
Complement bit. (CPL Px.y)
INC
Increment. (INC Px)
DEC
Decrement. (DEC Px)
DJNZ
Decrement and jump if not zero. (DJNZ Px,LABEL)
MOV
Px.y,C Move carry bit to Px.y.
CLR
Px.y
Clear bit Px.y.
SETB
Px.y
Set bit Px.y.
The last three seems not obviously read-modify-write instructions but actually they are. They read the entire
port latch value, modify the changed bit, then write the new value back to the port latch.
P0 – Port 0 (bit-addressable)
7
6
5
P0.7
P0.6
P0.5
r/w
r/w
r/w
Address: 80H
Bit
Name
7:0
P0[7:0]
4
P0.4
r/w
3
P0.3
r/w
2
P0.2
r/w
1
0
P0.1
P0.0
r/w
r/w
reset value: 1111 1111b
Description
Port 0.
Port 0 is an 8-bit open-drain port by default. Via setting P0UP (P0OR.0) P0 will
switch as weakly pulled up internally.
P0 has an alternative function as AD[7:0] while external memory accessing. During external Program Memory execution, SFR P0 cannot be accessed.
- 33 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
P0OR – P0 Option Register
7
6
Address: 86H
Bit
Name
7:1
-
0
P0UP
5
-
Name
7:0
P1[7:0]
3
-
2
-
1
0
P0UP
r/w
reset value: 0000 0000b
Description
Reserved.
Port 0 pull-up enable.
0 = Disable internal pull-up resistors of all 8-bits of Port 0.
1 = Enable internal pull-up resistors of all 8-bits of Port 0.
P1 – Port 1 (bit-addressable)
7
6
5
P1.7
P1.6
P1.5
r/w
r/w
r/w
Address: 90H
Bit
4
-
4
P1.4
r/w
3
P1.3
r/w
2
P1.2
r/w
1
0
P1.1
P1.0
r/w
r/w
reset value: 1111 1111b
2
P2.2
r/w
1
0
P2.1
P2.0
r/w
r/w
reset value: 1111 1111b
Description
Port 1.
Port 1 is an 8-bit quasi bi-directional I/O port.
P2 – Port 2 (bit-addressable)
7
6
5
P2.7
P2.6
P2.5
r/w
r/w
r/w
Address: A0H
4
P2.4
r/w
3
P2.3
r/w
Bit
Name
Description
7:0
P2[7:0]
Port 2.
Port 2 is an 8-bit quasi bi-directional I/O port. It has an alternative function as
A[15:8] while external memory accessing. During external Program Memory execution, SFR P2 cannot be accessed.
P3 – Port 3 (bit-addressable)
7
6
5
P3.7
P3.6
P3.5
r/w
r/w
r/w
Address: B0H
Bit
Name
7:0
P3[7:0]
4
P3.4
r/w
3
P3.3
r/w
Description
Port 3.
Port 3 is an 8-bit quasi bi-directional I/O port.
- 34 -
2
P3.2
r/w
1
0
P3.1
P3.0
r/w
r/w
reset value: 1111 1111b
P4 – Port 4 (bit-addressable)
7
6
5
P4.7
P4.6
P4.5
r/w
r/w
r/w
Address: D8H
4
P4.4
r/w
3
P4.3
r/w
2
P4.2
r/w
1
0
P4.1
P4.0
r/w
r/w
reset value: 1111 1111b
Bit
Name
Description
7:0
P4[7:0]
Port 4.
Port 4 is an 8-bit quasi bi-directional I/O port. It also possesses bit-addressable
feature as P0-P3. Note that a full 8-bit P4 is just on LQPF-48 package. PLCC-44,
PQFP-44, and TQFP-44 just have low nibble 4 bits of P4. DIP-40 does not have
this additional P4.
- 35 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
10. TIMERS/COUNTERS
N78E517A has three 16-bit programmable timers/counters.
10.1 Timer/Counters 0 and 1
Timer/Counter 0 and 1 on N78E517A are two 16-bit Timer/Counters. Each of them has two 8 bit registers
which form the 16 bit counting register. For Timer/Counter 0 they are TH0, the upper 8 bits register, and TL0,
the lower 8 bit register. Similarly Timer/Counter 1 has two 8 bit registers, TH1 and TL1. TCON and TMOD can
configure modes of Timer/Counter 0 and 1.
The Timer or Counter function is selected by the C/ T bit in TMOD. Each Timer/Counter has its own selection
bit. TMOD.2 selects the function for Timer/Counter 0 and TMOD.6 selects the function for Timer/Counter 1
When configured as a “Timer”, the timer counts clock cycles. The timer clock is 1/6 of the peripheral clock
(FPERIPH). In the “Counter” mode, the register increases on the falling edge of the external input pins T0 for
Timer 0 and T1 for Timer 1. If the sampled value is high in one machine-cycle and low in the next, a valid 1 to 0
transition on the pin is recognized and the count register increases.
In addition, each Timer/Counter can be set to operate in any one of four possible modes. Bits M0 and M1 in
TMOD do the mode selection.
TMOD – Timer 0 and 1 Mode
7
6
GATE
C/ T
r/w
Address: 89H
r/w
5
M1
4
M0
3
GATE
2
C/ T
r/w
r/w
r/w
r/w
1
M1
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7
GATE
6
C/T
Timer 1 Counter/Timer select.
0 = Timer 1 is incremented by internal peripheral clocks.
1 = Timer 1 is incremented by the falling edge of the external pin T1.
5
M1
4
M0
Timer 1 mode select.
M1
M0
Timer 1 Mode
0
0
Mode 0: 8-bit Timer/Counter with 5-bit pre-scalar (TL1[4:0])
0
1
Mode 1: 16-bit Timer/Counter
1
0
Mode 2: 8-bit Timer/Counter with auto-reload from TH1
1
1
Mode 3: Timer 1 halted
Timer 1 gate control.
0 = Timer 1 will clock when TR1 = 1 regardless of INT1 logic level.
1 = Timer 1 will clock only when TR1 = 1 and INT1 is logic 1.
- 36 -
0
M0
Bit
Name
3
GATE
Description
Timer 0 gate control.
0 = Timer 0 will clock when TR0 = 1 regardless of INT0 logic level.
1 = Timer 0 will clock only when TR0 = 0 and INT0 is logic 1.
2
C/T
Timer 0 Counter/Timer select.
0 = Timer 0 is incremented by internal peripheral clocks.
1 = Timer 0 is incremented by the falling edge of the external pin T0.
1
M1
0
M0
Timer 0 mode select.
M1
M0
Timer 0 Mode
0
0
Mode 0: 8-bit Timer/Counter with 5-bit pre-scalar (TL0[4:0])
0
1
Mode 1: 16-bit Timer/Counter
1
0
Mode 2: 8-bit Timer/Counter with auto-reload from TH0
1
1
Mode 3: TL0 as a 8-bit Timer/Counter and TH0 as a 8-bit
Timer
TCON – Timer 0 and 1 Control (bit-addressable)
7
6
5
4
TF1
TR1
TF0
TR0
r/w
r/w
r/w
r/w
Address: 88H
3
IE1
r/w
2
IT1
r/w
1
0
IE0
IT0
r/w
r/w
reset value: 0000 0000b
Bit
Name
7
TF1
Timer 1 overflow flag.
This bit is set when Timer 1 overflows. It is automatically cleared by hardware
when the program executes the Timer 1 interrupt service routine. Software can
also set or clear this bit.
6
TR1
Timer 1 run control.
0 = Timer 1 is halted. Clearing this bit will halt Timer 1 and the current count will
be preserved in TH1 and TL1.
1 = Timer 1 is enabled.
5
TF0
Timer 0 overflow flag.
This bit is set when Timer 0 overflows. It is automatically cleared via hardware
when the program executes the Timer 0 interrupt service routine. Software can
also set or clear this bit.
4
TR0
Timer 0 run control.
0 = Timer 0 is halted. Clearing this bit will halt Timer 0 and the current count will
be preserved in TH0 and TL0.
1 = Timer 0 is enabled.
TL0 – Timer 0 Low Byte
7
6
Description
5
4
3
2
1
0
TL0[7:0]
r/w
Address: 8AH
reset value: 0000 0000b
Bit
Name
7:0
TL0[7:0]
Description
Timer 0 low byte.
The TL0 register is the low byte of the 16-bit Timer 0.
- 37 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
TH0 – Timer 0 High Byte
7
6
5
4
3
2
1
0
TH0[7:0]
r/w
Address: 8CH
reset value: 0000 0000b
Bit
Name
7:0
TH0[7:0]
TL1 – Timer 1 Low Byte
7
6
Description
Timer 0 high byte.
The TH0 register is the high byte of the 16-bit Timer 0.
5
4
3
2
1
0
TL1[7:0]
r/w
Address: 8BH
reset value: 0000 0000b
Bit
Name
7:0
TL1[7:0]
TH1 – Timer 1 High Byte
7
6
Description
Timer 1 low byte.
The TL1 register is the low byte of the 16-bit Timer 1.
5
4
3
2
1
0
TH1[7:0]
r/w
Address: 8DH
reset value: 0000 0000b
Bit
Name
7:0
TH1[7:0]
Description
Timer 1 high byte.
The TH1 register is the high byte of the 16-bit Timer 1.
10.1.1 Mode 0 (13-bit Timer)
In Mode 0, the Timer/Counter is a 13-bit counter. The 13-bit counter consists of THx and the five lower bits of
TLx. The upper three bits of TLx are ignored. The Timer/Counter is enabled when TRx is set and either GATE
is 0 or INTx is 1. Gate = 1 allows the Timer to calculate the pulse width on external input pin INTx . When the
13-bit value moves from 1FFFH to 0000H, the Timer overflow flag TFx is set and an interrupt occurs if enabled.
Note that the peripheral clock is FOSC/2 in 12T mode and is FOSC in 6T mode. See Section 20. “CLOCK
SYSTEM” on page 103.
- 38 -
FPERIPH
1/6
C/T
0
1
T0 = P3.4
(T1 = P3.5)
0
TL0 (TL1)
4
7
TR0 (TR1)
0
GATE
7
TH0 (TH1)
INT0 = P3.2
(INT1 = P3.3)
TF0
(TF1)
Timer Interrupt
Figure 10–1. Timer/Counters 0 and 1 in Mode 0
10.1.2 Mode 1 (16-bit Timer)
Mode 1 is similar to Mode 0 except that the counting registers are fully used as a 16-bit counter. Roll-over occurs when a count moves FFFFH to 0000H. The Timer overflow flag TFx of the relevant Timer/Counter is set
and an interrupt will occurs if enabled.
FPERIPH
T0 = P3.4
(T1 = P3.5)
1/6
C/T
TL0 (TL1)
0
1
0
7
0
7
TR0 (TR1)
GATE
TH0 (TH1)
INT0 = P3.2
(INT1 = P3.3)
TF0
(TF1)
Timer Interrupt
Figure 10–2. Timer/Counters 0 and 1 in Mode 1
10.1.3 Mode 2 (8-bit Auto-reload Timer)
In Mode 2, the Timer/Counter is in auto-reload mode. In this mode, TLx acts as an 8-bit count register whereas
THx holds the reload value. When the TLx register overflows from FFH to 00H, the TFx bit in TCON is set, TLx
is reloaded with the contents of THx, and the counting process continues from here. The reload operation
leaves the contents of the THx register unchanged. This feature is best suitable for UART baud rate generator
for it runs without continuous software intervention. Note that only Timer1 can be the baud rate source for
UART. Counting is enabled by the TRx bit and proper setting of GATE and INTx pins. The functions of GATE
and INTx pins are just the same as Mode 0 and 1.
- 39 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
FPERIPH
1/6
C/T
TL0 (TL1)
0
0
1
T0 = P3.4
(T1 = P3.5)
7
TF0
(TF1)
Timer Interrupt
TR0 (TR1)
GATE
0
INT0 = P3.2
(INT1 = P3.3)
7
TH0 (TH1)
Figure 10–3. Timer/Counter 0 and 1 in Mode 2
10.1.4 Mode 3 (Two Separate 8-bit Timers)
Mode 3 has different operating methods for the two Timer/Counters. For Timer/Counter 1, Mode 3 simply
freezes the counter. Timer/Counter 0, however, configures TL0 and TH0 as two separate 8 bit count registers
in this mode. TL0 uses the Timer/Counter 0 control bits C/ T , GATE, TR0, INT0 , and TF0. The TL0 also can
be used as a 1-to-0 transition counter on pin T0 as determined by C/ T (TMOD.2). TH0 is forced as a clock
cycle counter and takes over the usage of TR1 and TF1 from Timer/Counter 1. Mode 3 is used in case which
an extra 8 bit timer is needed. If Timer/Counter 0 is configured in Mode 3, Timer/Counter 1 can be turned on or
off by switching it out of or into its own Mode 3. It can still be used in Modes 0, 1 and 2 although its flexibility is
restricted. It no longer has control over its overflow flag TF1 and the enable bit TR1. However Timer 1 can still
be used as a Timer/Counter and retains the use of GATE and INT1 pin. It can be used as a baud rate generator for the serial port or other application not requiring an interrupt.
FPERIPH
T0 = P3.4
1/6
C/T
TL0
0
1
0
7
TF0
Timer 0 Interrupt
7
TF1
Timer 1 Interrupt
TR0
GATE
INT0 = P3.2
TH0
TR1
0
Figure 10–4. Timer/Counter 0 in Mode 3
- 40 -
10.2 Timer/Counter 2
Timer/Counter 2 is a 16-bit up counter, which is configured by the T2MOD and T2CON registers. The count
stores in two 8-bit cascade registers TH2 and TL2. Timer/Counter 2 is additionally equipped with a capture or
reload capability. It also can be configured as the baud rate generator for UART or a square wave generator.
The features listed above could be achieved because of the addition Timer/Counter 2 capture registers
RCAP2H and RCAP2L. As with the Timer 0 and Timer 1 counters, there exists considerable flexibility in selecting and controlling the clock and in defining the operating mode. The clock source for Timer/Counter 2 may be
selected from either the external T2 pin ( C/ T2 (T2CON.1) = 1) or the crystal oscillator ( C/ T2 = 0). The clock is
then enabled when TR2 (T2CON.2) is a 1, and disabled when TR2 is a 0. The following registers are related to
Timer/Counters 2 function.
T2CON – Timer 2 Control (bit-addressable)
7
6
5
4
TF2
EXF2
RCLK
TCLK
r/w
r/w
r/w
r/w
Address: C8H
3
EXEN2
r/w
2
TR2
r/w
1
C/ T2
CP/RL2
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7
TF2
Timer 2 overflow flag.
This bit is set when Timer 2 overflows. If the Timer 2 interrupt and the global interrupt are enable, setting this bit will make CPU execute Timer 2 interrupt service
routine. This bit is not automatically cleared via hardware and must be cleared via
software.
TF2 will not be set while Timer 2 is configured in the baud rate generator or clockout mode.
6
EXF2
Timer 2 external flag.
This bit is set via hardware when a 1-to-0 transition on the T2EX input pin occurs
and EXEN2 is logic 1. When the Timer 2 interrupt is enabled, setting this bit causes the CPU to execute the Timer 2 Interrupt service routine. This bit is not automatically cleared via hardware and must be cleared via software.
5
RCLK
Receive clock flag.
This bit selects which Timer is used for the UART‟s receive clock in serial Mode 1
or 3.
0 = Timer 1 overflows is used for UART receive baud rate clock.
1 = Timer 2 overflows is used for UART receive baud rate clock.
4
TCLK
Transmit clock flag.
This bit selects which Timer is used for the UART‟s transmit clock in serial Mode 1
or 3.
0 = Timer 1 overflows is used for UART transmit baud rate clock.
1 = Timer 2 overflows is used for UART transmit baud rate clock.
- 41 -
0
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Bit
Name
Description
3
EXEN2
Timer 2 external enable.
This bit enables 1-to-0 transitions on T2EX trigger.
0 = 1-to-0 transitions on T2EX is ignored.
1 = 1-to-0 transitions on T2EX will set EXF2 logic 1. If Timer 2 is configured in
capture or auto-reload mode, the 1-to-0 transitions on T2EX will cause capture or reload event.
2
TR2
Timer 2 run control.
0 = Timer 2 is halted. Clearing this bit will halt Timer 2 and the current count will
be preserved in TH2 and TL2.
1 = Timer 2 is enabled.
1
C/T2
Timer 2 Counter/Timer select.
0 = Timer 2 is incremented by internal peripheral clocks.
1 = Timer 2 is incremented by the falling edge of the external pin T2.
If Timer 2 would like to be set in clock-out mode, C/T2 must be 0.
0
CP/RL2
Timer 2 Capture or Reload select.
This bit selects whether Timer 2 functions in capture or auto-reload mode. EXEN2
must be logic 1 for 1-to-0 transitions on T2EX to be recognized and used to trigger
captures or reloads. If RCLK or TCLK is set, this bit is ignored and Timer 2 will
function in auto-reload mode.
0 = Auto-reload on Timer 2 overflow or 1-to-0 transition on T2EX pin.
1 = Capture on 1-to-0 transition at T2EX pin.
T2MOD – Timer 2 Mode
7
6
Address: C9H
Bit
Name
7:2
-
1
T2OE
0
-
5
-
4
-
3
-
2
-
1
0
T2OE
r/w
reset value: 0000 0000b
Description
Reserved.
Timer 2 clock-out enable.
0 = Disable Timer 2 clock-out function. T2 pin functions either as a standard port
pin or as a counter input for Timer 2.
1 = Enable Timer 2 clock-out function. Timer 2 will drive T2 pin with a clock output
if C/T2 is 0.
Reserved.
RCAP2L – Timer 2 Reload/Capture Low Byte
7
6
5
4
3
RCAP2L[7:0]
r/w
Address: CAH
2
1
reset value: 0000 0000b
Bit
Name
Description
7:0
RCAP2L[7:0]
Timer 2 reload/capture low byte.
This register captures and stores the low byte of Timer 2 when Timer 2 is configured in capture mode. When Timer 2 is in auto-reload mode, baud rate
generator mode, or clock-out mode, it holds the low byte of the reload value.
- 42 -
0
RCAP2H – Timer 2 Reload/Capture High Byte
7
6
5
4
3
RCAP2H[7:0]
r/w
Address: CBH
2
1
reset value: 0000 0000b
Bit
Name
Description
7:0
RCAP2H[7:0]
Timer 2 reload/capture high byte.
This register captures and stores the high byte of Timer 2 when Timer 2 is
configured in capture mode. When Timer 2 is in auto-reload mode, baud rate
generator mode, or clock-out mode, it holds the high byte of the reload value.
TL2 – Timer 2 Low Byte
7
6
5
4
0
3
2
1
0
TL2[7:0]
r/w
Address: CCH
reset value: 0000 0000b
Bit
Name
7:0
TL2[7:0]
TH2 – Timer 2 High Byte
7
6
Description
Timer 2 low byte.
The TL2 register is the low byte of the 16-bit Timer 2.
5
4
3
2
1
0
TH2[7:0]
r/w
Address: CDH
reset value: 0000 0000b
Bit
Name
7:0
TH2[7:0]
Description
Timer 2 high byte.
The TH2 register is the high byte of the 16-bit Timer 2.
Timer/Counter 2 provides four operating mode which can be selected by control bits in T2CON and T2MOD as
shown in table below. Note that the TH2 and TL2 are accessed separately. It is strongly recommended that the
user stop Timer 2 temporally for a reading from or writing to TH2 and TL2. The free-running reading or writing
may cause unpredictable situation.
- 43 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Table 10–1. Timer 2 Operating Modes
RCLK (T2CON.5)
or
TCLK (T2CON.4)
CP/RL2 (T2CON.0)
T2OE (T2MOD.1)
16-bit capture
0
1
0
16-bit auto-reload
0
0
0
Baud rate generator
1
X
0
[2]
0
0
1
Timer 2 Mode
[1]
Clock-out
[1] The capture is valid while EXEN2 (T2CON.3) is a 1. Or Timer/Counter 2 behaves just like a 16-bit timer/counter.
[2] C/T2 (T2CON.1) must be 0.
10.2.1 Capture Mode
The capture mode is enabled by setting the CP/RL2 bit in the T2CON register to 1. In the capture mode, Timer/Counter 2 serves as a 16 bit up counter. When the counter rolls over from FFFFH to 0000H, the TF2 bit is
set, which will generate an Timer 2 interrupt request. If the EXEN2 bit is set, then a negative transition of T2EX
pin (alternative function of P1.1) will cause the value in the TL2 and TH2 register to be captured by the
RCAP2L and RCAP2H registers. The TH2 and TL2 keeps on counting while this capture event occurs. This
capture action also causes the EXF2 (T2CON.6) bit set, which will also generate an Timer 2 interrupt. If Timer
2 interrupt enabled, both TF2 and EXF2 flags will generate interrupt vectoring to the same location. The user
should check which one triggers the Timer 2 interrupt in the interrupt service routine.
FPERIPH
T2 = P1.0
1/6
C/T2
TL2
0
1
TH2
0
7 0
7
0
7 0
7
TF2
TR2
Timer 2 Interrupt
T2EX = P1.1
RCAP2L
RCAP2H
EXF2
EXEN2
Figure 10–5. Timer/Counter 2 in Capture Mode
10.2.2 Auto-reload Mode
The auto-reload mode is enabled by clearing the CP/RL2 bit in the T2CON register. In this mode, Timer/Counter 2 is a 16 bit up counter. When the counter rolls over from FFFFH, TF2 (T2CON.7) is set as 1 and a
reload is generated that causes the contents of the RCAP2L and RCAP2H registers to be reloaded into the
TL2 and TH2 registers respectively. If the EXEN2 bit is set, then a negative transition on T2EX pin will also
cause a reload. This action also sets the EXF2 bit in T2CON.
- 44 -
FPERIPH
T2 = P1.0
1/6
C/T2
TL2
0
1
TH2
0
7 0
7
0
7 0
7
TF2
TR2
RCAP2L
T2EX = P1.1
Timer 2 Interrupt
RCAP2H
EXF2
EXEN2
Figure 10–6. Timer/Counter 2 in Auto-reload Mode
10.2.3 Baud Rate Generator Mode
The Timer 2 can generate the baud rate for UART in its Mode 1 and 3. The baud rate generator mode is enabled by setting either the RCLK or TCLK bits in T2CON register. While in the baud rate generator mode, Timer/Counter 2 is a 16 bit counter with auto-reload when the count rolls over from FFFFH. However, rolling over
is used to generate the shift clock for UART data rather than to set the TF2 bit. If EXEN2 bit is set, then a negative transition of the T2EX pin will set EXF2 bit in the T2CON register and cause an interrupt request. It simply
provides a external interrupt. Note that TCLK and RCLK are selected individually, the serial port transmit rate
can be different from the receive rate. For example the transmit clock can be generated from Timer 2 by setting
TCLK and the receive clock from Timer 1 by clearing RCLK.
Timer 1
Overflow
1/2
FPERIPH
T2 = P1.0
C/T2
TL2
0
1
Timer 2
Overflow
TH2
7 0
0
7
TR2
0
RCLK
1
0
1
SMOD
(PCON.7)
1/16
Rx clock
1/16
Tx clock
TCLK
0
7 0
RCAP2L
7
1
0
RCAP2H
T2EX = P1.1
EXEN2
EXF2
Timer 2 Interrupt
Figure 10–7. Timer/Counter 2 in Baud Rate Generator Mode
- 45 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
10.2.4 Clock-out Mode
Timer 2 is equipped with a clock-out feature, which outputs a 50% duty cycle clock on P1.0. It can be invoked
as a programmable clock generator. To configure Timer 2 with clock-out mode, software must initiate it by setting bit T2OE (TMOD.1) = 1, C/ T2 = 0 and CP/RL2 = 0. Setting bit TR2 will start the clock output. This mode
is similar to the baud rate generator mode which does not generate an interrupt while Timer 2 overflow. Similar
with the baud rate generator mode, T2EX can also be configured as a simple external interrupt.
The clock-out frequency follows the equation
FOSC
22
EN6T
65536 RCAP2H,RCAP2L
.
In this formula, EN6T is bit 6 of CONFIG3. While EN6T = 0, the clock system runs under 6T mode and the
clock-out frequency will be double of that in 12T mode. (RCAP2H,RCAP2L) in the formula means
256 RCAP2H RCAP2L .
FPERIPH
TL2
TH2
7 0
0
7
TR2
0
7 0
RCAP2L
7
RCAP2H
T2EX = P1.1
EXEN2
EXF2
Timer 2 Interrupt
Figure 10–8. Timer/Counter 2 in Clock-out Mode
- 46 -
1/2
T2 = P1.0
11. WATCHDOG TIMER
11.1 Functional Description of Watchdog Timer
N78E517A provides one Watchdog Timer to serve as a system monitor, which improve the reliability of the
system. Watchdog Timer is useful for systems that are susceptible to noise, power glitches, or electrostatic
discharge. The Watchdog Timer is basic a setting of dividers that divide the peripheral clock. The divider output
is selectable and determines the time-out interval. When the time-out interval is fulfilled, a direct system reset
will occur.
10kHz
Internal RC
Clock
Divider
WDT counter (6-bit)
overflow
WDTRF
Watchdog Timer
Reset
clear
IDL (PCON.0)
PD (PCON.1)
WIDPD
FLOSC
WPS[2:0]
WDCLR
WDTEN
Figure 11–1. Watchdog Timer Block Diagram
The Watchdog Timer should first be reset 00H by using WDCLR(WDCON.6) to ensure that the timer starts
from a known state. The WDCLR bit is used to reset the Watchdog Timer. This bit is self-cleared thus the user
doesn‟t need to clear it. After writing a 1 to WDCLR, the hardware will automatically clear it. After WDTEN set
as 1, the Watchdog Timer starts counting. The time-out interval is selected by the three bits WPS2, WPS1, and
WPS0 (WDCON[2:0]). When the selected time-out occurs, the Watchdog Timer will reset the system directly.
Once a reset due to Watchdog Timer occurs, the Watchdog Timer reset flag WDTRF (WDCON.3) will be set.
This bit keeps unchanged after any reset other than a power-on reset. The user may clear WDTRF via software. In general, software should restart the counter to put it into a known state by setting WDCLR. The
Watchdog Timer also provides an WIDPD bit (WDCON.4) to allow the Watchdog Timer continuing running after the system enters into Idle or Power Down operating mode.
WDT counter should be specially taken care. The hardware automatically clears WDT counter after entering
into or being woken-up from Idle or Power Down mode. It prevents unconscious system reset.
- 47 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
CONFIG3
7
CWDTEN
r/w
6
EN6T
r/w
Bit
Name
7
CWDTEN
5
ROG
r/w
4
CKF
r/w
3
INTOSCFS
r/w
2
1
0
FOSC
r/w
unprogrammed value: 1111 1111b
Description
CONFIG Watchdog Timer enable.
1 = Disable Watchdog Timer after all resets.
0 = Enable Watchdog Timer after all resets.
WDCON – Watchdog Timer Control (TA protected)
7
6
5
4
3
2
1
0
WDTEN[1]
WDCLR
WIDPD[2]
WDTRF[3]
WPS2[2]
WPS1[2]
WPS0[2]
r/w
w
r/w
r/w
r/w
r/w
r/w
Address: AAH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
7
WDTEN
Watchdog Timer enable.
0 = Disable Watchdog Timer.
1 = Enable Watchdog Timer. The WDT counter starts running.
6
WDCLR
Watchdog Timer clear.
Setting this bit will reset the Watchdog Timer count to 00H. It puts the counter in a
known state and prohibit the system from reset. Note that this bit is written-only
and has no need to be cleared via software.
5
-
4
WIDPD
Watchdog Timer running in Idle and Power Down mode.
This bit decides whether Watchdog Timer runs in Idle or Power Down mode.
0 = WDT counter is halted while CPU is in Idle or Power Down mode.
1 = WDT keeps running while CPU is in Idle or Power Down mode.
3
WDTRF
Watchdog Timer reset flag.
When the CPU is reset by Watchdog Timer time-out event, this bit will be set via
hardware. This flag is recommended to be cleared via software.
2
WPS2
1
WPS1
Watchdog Timer clock pre-scalar select.
These bits determine the scale of the clock divider for WDT counter. The scale is
from 1/1 through 1/256. See Table 11–1.
Reserved.
0
WPS0
[1] WDTEN is initialized by the inversed value of CWDTEN (CONFIG3.7) after all resets.
[2] WIDPD and WPS[2:0] are cleared after power-on reset, and keep unchanged after any other resets.
[3] WDTRF will be cleared after power-on reset, be set after Watchdog Timer reset, and remains unchanged after any other resets.
The Watchdog time-out interval is determined by the formula
1
64 . Where FILRC is
FLOSC clock dividerscalar
the frequency of internal 10kHz RC. The following table shows an example of the Watchdog time-out interval
under different FWCK and pre-scalars.
- 48 -
Table 11–1. Watchdog Timer-Out Interval under different pre-scalars
WPS2 WPS1 WPS0
Clock Divider
Scale
Typical Watchdog Time-out
Interval (FILRC = ~10kHz)
0
0
0
1/1
6.40ms
0
0
1
1/2
12.80ms
0
1
0
1/8
51.20ms
0
1
1
1/16
102.40ms
1
0
0
1/32
204.80ms
1
0
1
1/64
409.60ms
1
1
0
1/128
819.20ms
1
1
1
1/256
1.638s
11.2 Applications of Watchdog Timer
The main application of the Watchdog Timer is for the system monitor. This is important in real-time control
applications. In case of some power glitches or electro-magnetic interference, the processor may begin to execute erroneous codes and operate in an unpredictable state. If this is left unchecked the entire system may
crash. Using the Watchdog Timer during software development will require the user to select ideal watchdog
reset locations for inserting instructions to reset the Watchdog Timer. By inserting the instruction setting
WDCLR, it will allow the code to run without any Watchdog Timer reset. However If any erroneous code executes by any power of other interference, the instructions to clear the Watchdog Timer counter will not be executed at the required instants. Thus the Watchdog Timer reset will occur to reset the system start from an erroneously executing condition. The user should remember that WDCON requires a timed access writing.
- 49 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
12. POWER DOWN WAKING-UP TIMER
12.1 Functional Description of Power Down Waking-up Timer
N78E517A provides another free-running Timer, Power Down waking-up timer which serves as a event timer
or a durational system supervisor in a monitoring system which generally operates in Idle or Power Down
modes. This timer constructs basically by a set of dividers that divide the peripheral clock. The divider output is
selectable and determines the time-out interval. When the time-out interval is fulfilled, it will wake the system
up from Idle or Power Down mode and an interrupt event will occur.
10kHz
Internal RC
FLOSC
Clock
Divider
PDT counter (6-bit)
overflow
clear
PDTEN
PPS[2:0]
Power Down wakingup timer interrupt
PDTF
EPDT
PCLR
Figure 12–1. Power Down Waking-up Timer Block Diagram
The Power Down waking-up timer should first be reset 00H by using PDCLR(PDCON.6) to ensure that the timer starts from a known state. The PDCLR bit is used to restart the Power Down waking-up timer. This bit is
self-cleared thus the user doesn‟t need to clear it. After writing a 1 to PDCLR, the hardware will automatically
clear it. After PDTEN set as 1, the Power Down waking-up timer will start counting clock cycles. The time-out
interval is selected by the three bits PPS2, PPS1, and PPS0 (PDCON[2:0]). When the selected time-out occurs, the Power Down waking-up timer will set the interrupt flag PDTF (PDCON.5). The Power Down wakingup timer interrupt enable bit locates at bit 1 in EIE. In general, software should restart the counter to put it into a
known state by setting WDCLR.
PDCON – Power Down Waking-up Timer Control
7
6
5
4
PDTEN
PDCLR
PDTF
r/w
w
r/w
Address: ABH
3
-
2
PPS2
r/w
1
0
PPS1
PPS0
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7
PDTEN
Power Down waking-up timer enable.
0 = Disable Power Down waking-up timer.
1 = Enable Power Down waking-up timer. The PDT counter starts running.
6
PDCLR
Power Down waking-up timer clear.
Setting this bit will reset the Power Down waking-up timer count to 00H. It put the
counter in a known state. This bit is written-only and has no need to be cleared via
software.
5
PDTF
Power Down waking-up timer Interrupt Flag.
This bit will be set via hardware when PDT counter overflows. This bit must be
cleared via software.
- 50 -
Bit
Name
4:3
-
2
PPS2
1
PPS1
0
PPS0
Description
Reserved.
Power Down waking-up timer clock pre-scalar select.
These bits determine the scale of the clock divider for PDT counter. The scale is
from 1/1 through 1/1024. See Table 12–1.
The Power Down waking-up time-out interval is determined by the formula
1
64
FLOSC clock dividerscalar
where FILRC is the frequency of internal 10kHz RC. The following table shows an example of the Power Down
waking-up time-out interval under different pre-scalars.
Table 12–1. Power Down Waking-up Timer-Out Interval under different pre-scalars
Clock Divider
Scale
Typical Power Down Waking-up
Time-out Interval (FILRC = ~10kHz)
PPS2
PPS1
PPS0
0
0
0
1/1
6.40ms
0
0
1
1/4
25.60ms
0
1
0
1/8
51.20ms
0
1
1
1/32
204.80ms
1
0
0
1/64
409.60ms
1
0
1
1/256
1.638s
1
1
0
1/512
3.277s
1
1
1
1/1024
6.554s
12.2 Applications of Power Down Waking-up Timer
The main application of the Power Down waking-up timer is a simple timer. The PDTF flag will be set while the
Power Down waking-up timer completes the selected time interval. The software polls the PDTF flag to detect
a time-out and the PDCLR allows software to restart the timer. The Power Down waking-up timer can also be
used as a very long timer. Every time the time-out occurs, an interrupt will occur if the individual interrupt EPDT
(EIE.1) and global interrupt enable EA is set.
In some application of low power consumption, the CPU usually stays in Idle mode when nothing needs to be
served to save power consumption. After a while the CPU will be woken up to check if anything needs to be
served at an interval of programmed period implemented by Timer 0, 1 or 2. However, the current consumption
of Idle mode still keeps at a “mA” level. To further reducing the current consumption to “μA” level, the CPU
should stay in Power Down mode when nothing needs to be served, and has the ability of waking up at a pro-
- 51 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
grammable interval. N78E517A is equipped with this useful function. It provides a very low power internal RC
10kHz. Along with the low power consumption application, the Power Down Waking-up timer needs to count
under Idle and Power Down mode and wake CPU up from Idle or Power Down mode. The demo code to accomplish this feature is shown below.
The demo code of Power Down waking-up timer waking up CPU from Power Down.
ORG
LJMP
0000H
START
ORG
LJMP
004BH
PDT_ISR
ORG
PDT_ISR:
ORL
ANL
RETI
0100H
PDCON,#01000000B
PDCON,#11011111B
;Clear Power Down Waking-up timer counter
;Clear Power Down Waking-up timer interrupt flag
PDCON,#00000111B
EIE,#00000010B
EA
PDCON,#10000000B
;Choose interval length
;Enable Power Down Waking-up timer interrupt
START:
ORL
ORL
SETB
ORL
;Enable Power Down Waking-up timer to run
;********************************************************************
;Enter into Power Down mode
;********************************************************************
LOOP:
ORL
PCON,#02H
LJMP
LOOP
- 52 -
13. SERIAL PORT
N78E517A includes one enhanced full duplex serial port. The serial port supports three modes of full duplex
UART (Universal Asynchronous Receiver and Transmitter) in Mode 1, 2, and 3. Full duplex means it can
transmit and receive simultaneously. The serial port is also receive-buffered, meaning it can commence reception of a second byte before a previously received byte has been read from the register. The serial port receive
and transmit registers are both accessed at SBUF. Writing to SBUF loads the transmit register, and reading
SBUF accesses a physically separate receive register. There are four operation modes in serial port. In all four
modes, transmission initiates by any instruction that uses SBUF as a destination register. Note that before serial port function works, the port latch bits of P3.0 and P3.1 (for RXT and TXD pins) have to be set to 1.
SCON – Serial Port Control (bit-addressable)
7
6
5
4
SM0
SM1
SM2
REN
r/w
r/w
r/w
r/w
Address: 98H
Bit
Name
7
SM0
6
SM1
5
SM2
3
TB8
r/w
2
RB8
r/w
1
0
TI
RI
r/w
r/w
reset value: 0000 0000b
Description
Serial port mode select.
See Table 13–1. Serial Port Mode Description for details.
Multiprocessor communication mode enable.
The function of this bit is dependent on the serial port mode.
Mode 0:
This bit has no effect.
Mode 1:
This bit checks valid stop bit.
0 = Reception is always valid no matter the logic level of stop bit.
1 = Reception is ignored if the received stop bit is not logic 1.
Mode 2 or 3:
For multiprocessor communication.
th
0 = Reception is always valid no matter the logic level of the 9 bit.
th
1 = Reception is ignored if the received 9 bit is not logic 1.
4
REN
Receive enable.
0 = Disable serial port reception.
1 = Enable serial port reception in Mode 1,2, and 3. In Mode 0, reception is initialized by the condition REN = 1 and RI = 0.
3
TB8
9 transmit bit.
th
This bit defines the state of the 9 transmission bit in serial port Mode 2 and 3. It
is not used in Mode0 and 1.
2
RB8
9 receive bit.
th
The bit identifies the logic level of the 9 received bit in Modes 2 and 3. In Mode
1, if SM2 0, RB8 is the logic level of the received stop bit. RB8 is not used in
Mode 0.
th
th
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Bit
Name
Description
1
TI
Transmission interrupt flag.
This flag is set via hardware when a byte of data has been transmitted by the
th
UART after the 8 bit in Mode 0 or the last bit of data in other modes. When the
UART interrupt is enabled, setting this bit causes the CPU to execute the UART
interrupt service routine. This bit must be cleared manually via software.
0
RI
Receiving interrupt flag.
This flag is set via hardware when a 8-bit or 9-bit data has been received by the
th
UART after the 8 bit in Mode 0, after sampling the stop bit in Mode 1, or after
th
sampling the 9 bit in Mode 2 and 3. SM2 bit has restriction for exception. When
the UART interrupt is enabled, setting this bit causes the CPU to execute to the
UART interrupt service routine. This bit must be cleared manually via software.
Table 13–1. Serial Port Mode Description
Mode
SM0
SM1
Description
Data Bits
Baud Rate
0
0
0
Synchronous
8
FOSC divided by 12 for 12T mode, by 6 for 6T mode
1
0
1
Asynchronous
10
Timer 1 overflow rate divided by 16 or divided by 32 , or Timer 2
overflow rate divided by 16
2
1
0
Asynchronous
11
FOSC divided by 32 or 64
[1]
[1]
for 12T mode, by 16 or 32
[1]
for 6T mode
[1]
3
1
1
Asynchronous
11
Timer 1 overflow rate divided by 16 or divided by 32 , or Timer 2
overflow rate divided by 16
[1] While SMOD (PCON.7) is logic 0.
PCON – Power Control
7
6
SMOD
r/w
Address: 87H
5
-
4
3
2
1
0
POF
GF1
GF0
PD
IDL
r/w
r/w
r/w
r/w
r/w
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
7
SMOD
Serial port double baud rate enable.
Setting this bit doubles the serial port baud rate in UART mode 2 and mode 1 or 3
only if Timer 1 overflow is used as the baud rate source. See Table 13–1. Serial
Port Mode Description in details.
- 54 -
SBUF – Serial Data Buffer
7
6
5
4
3
2
1
0
SBUF[7:0]
r/w
Address: 99H
reset value: 0000 0000b
Bit
Name
Description
7:0
SBUF[7:0]
Serial data buffer.
This byte actually consists two separate registers. One is the receive resister,
and the other is the transmit buffer. When data is moved to SBUF, it goes to the
transmit buffer and is shifted for serial transmission. When data is moved from
SBUF, it comes from the receive buffer.
The transmission is initiated through moving a byte to SBUF.
13.1 Mode 0
Mode 0 provides synchronous communication with external devices. Serial data enters and exits through RXD
pin. TXD outputs the shift clock. 8 bits are transmitted or received. Mode 0 therefore provides half-duplex
communication because the transmitting or receiving data is via the same data line RXD. The baud rate is
fixed at 1/12 the oscillator frequency in 12T Mode or 1/6 the oscillator frequency in 6T Mode. Note that whenever transmitting or receiving, the serial clock is always generated by the microcontroller. Thus any device on
the serial port in Mode 0 must accept the microcontroller as the Master. Figure 13–1 shows a simplified functional diagram of the serial port in Mode 0 and associated timing. Note that the peripheral clock is FOSC/2 in 12T
mode and is FOSC in 6T mode. See Section 20. “CLOCK SYSTEM” on page 103.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Figure 13–1. Serial Port Mode 0 Function Block and Timing Diagram
- 56 -
As shown there is one bi-direction data line (RXD) and one shift clock line (TXD). The shift clock is used to shift
data in or out of the serial port controller bit by bit for a serial communication. Data bits enter or exit LSB first.
The band rate is equal to the shift clock frequency.
Transmission is initiated by any instruction writes to SBUF. The control block will then shift out the clock and
begin to transfer data until all 8 bits are complete. Then the transmitted flag TI (SCON.1) will be set 1 to indicate one byte transmitting complete.
Reception is initiated by the condition REN (SCON.4) = 1 and RI (SCON.0) = 0. This condition tells the serial
port controller that there is data to be shifted in. This process will continue until 8 bits have been received.
Then the received flag RI will be set as 1. The user can clear RI to trigger the next byte reception.
13.2 Mode 1
Mode 1 supports asynchronous, full duplex serial communication. The asynchronous mode is commonly used
for communication with PCs, modems or other similar interfaces. In Mode 1, 10 bits are transmitted (through
TXD) or received (through RXD) including a start bit (logic 0), 8 data bits (LSB first) and a stop bit (logic 1). The
baud rate is determined by the Timer 1 or Timer 2 overflow rate according to RCLK and TCLK bits in T2CON.
SMOD (PCON.7) setting 1 makes the baud rate double while Timer 1 is selected as the clock source. Figure
13–2 shows a simplified functional diagram of the serial port in Mode 1 and associated timings for transmit and
receive.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Figure 13–2. Serial Port Mode 1 Function Block and Timing Diagram
- 58 -
Transmission is initiated by any writing instructions to SBUF. Transmission takes place on TXD pin. First the
start bit comes out, the 8-bit data follows to be shifted out and then ends with a stop bit. After the stop bit appears, TI (SCON.1) will be set to indicate one byte transmission complete. All bits are shifted out depending on
the rate determined by the baud rate generator.
Once the baud rate generator is activated and REN (SCON.4) is 1, the reception can begin at any time. Reception is initiated by a detected 1-to-0 transition at RXD. Data will be sampled and shifted in at the selected
baud rate. In the midst of the stop bit, certain conditions must be met to load SBUF with the received data:
1. RI (SCON.0) = 0, and
2. Either SM2 (SCON.5) = 0, or the received stop bit = 1 while SM2 = 1.
If these conditions are met, then the SBUF will be loaded with the received data, the RB8 (SCON.2) with stop
bit, and RI will be set. If these conditions fail, there will be no data loaded and RI will remain 0. After above receiving progress, the serial control will look forward another 1-0 transition on RXD pin in order to start next data
reception.
13.3 Mode 2
Mode 2 supports asynchronous, full duplex serial communication. Different from Mode1, there are 11 bits to be
th
transmitted or received. They are a start bit (logic 0), 8 data bits (LSB first), a programmable 9 bit TB8 or RB8
th
bit and a stop bit (logic 1). The most common use of 9 bit is to put the parity bit in it. The baud rate is fixed as
1/32 or 1/64 the oscillator frequency depending on SMOD bit. (Condition above is under 12T mode. Under 6T
mode, the baud rate will be 1/16 or 1/32 the oscillator frequency.) Figure 13–3 shows a simplified functional
diagram of the serial port in Mode 2 and associated timings for transmit and receive.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Figure 13–3. Serial Port Mode 2 Function Block and Timing Diagram
- 60 -
Transmission is initiated by any writing instructions to SBUF. Transmission takes place on TXD pin. First the
start bit comes out, the 8-bit data and bit TB8 (SCON.3) follows to be shifted out and then ends with a stop bit.
After the stop bit appears, TI will be set to indicate the transmission complete.
While REN is set, the reception is allowed at any time. A falling edge of a start bit on RXD will initiate the reth
ception progress. Data will be sampled and shifted in at the selected baud rate. In the midst of the 9 bit, certain conditions must be met to load SBUF with the received data:
1. RI (SCON.0) = 0, and
th
2. Either SM2(SCON.5) = 0, or the received 9 bit = 1 while SM2 = 1.
If these conditions are met, then the SBUF will be loaded with the received data, the RB8(SCON.2) with TB8
bit and RI will be set. If these conditions fail, there will be no data loaded and RI will remain 0. After above receiving progress, the serial control will look forward another 1-0 transition on RXD pin in order to start next data
reception.
13.4 Mode 3
Mode 3 has the same operation as Mode 2, except its baud rate clock source. As shown is Figure 13–4, Mode
3 uses Timer 1 or Timer 2 overflow as its baud rate clock.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Figure 13–4. Serial Port Mode 3 Function Block and Timing Diagram
- 62 -
13.5 Baud Rate
Table 13–2. UART Baud Rate Formulas
UART
mode
EN6T (CONFIG3.6) value
Baud rate clock source
1
(12T mode)
0
(6T mode)
0
Oscillator
FOSC / 12
FOSC / 6
2
Oscillator
2SMOD
FOSC
64
2SMOD
FOSC
32
2SMOD
FOSC
32
12 256 TH1
2SMOD
FOSC
16
12 256 TH1
FOSC
[3]
32 65536 RCAP2H,RCAP2L
FOSC
16 65536 RCAP2H,RCAP2L
[1]
Timer/Counter 1 overflow
1 or 3
[2]
Timer/Counter 2 overflow
[1] Timer 1 is configured as a timer in auto-reload mode (Mode 2).
[2] Timer 2 is configured as a timer in baud rate generator mode.
[3] (RCAP2H,RCAP2L) in the formula means 256 RCAP2H RCAP2L .
Note that in using Timer 1 as the baud rate generator, the interrupt should be disabled. In using Timer 2, the
interrupt is automatically switched off. The Timer itself can be configured for either “Timer” or “Counter” operation. Timer 1 can be in any of its 3 running modes. In the most typical applications, it is configured for “Timer”
operation, in the auto-reload mode (Mode2). If Timer 1 is used as the baud rate generator, the reloaded value
is stored in TH1. Therefore the baud rate is determined by TH1 value. If Timer 2 is used, the user should configure it in baud rate generator mode (RCLK or TCLK in T2CON is logic 1) and give 16-bit reloaded value in
RCAP2H and RCAP2L.
Table 13–3 lists various commonly used baud rates and how they can be obtained from Timer 1. In this mode,
Timer 1 as an auto-reload Timer operates in 12T mode and SMOD (PCON.7) is 0. Table 13–4 is for Timer 2 as
the baud rate generator. Timer 2 operates in baud rate generator mode in 12T mode. In 6T mode, the baud
rate generated from both Timer 1 and Timer 2 overflows will be doubled.
Table 13–3. Timer 1 Generated Commonly Used Baud Rates
Oscillator Frequency (MHz)
TH1 reload value
11.0592
14.7456
18.432
22.1184
36.864
Baud Rate
57600
FFh
38400
FFh
19200
FEh
FDh
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FBh
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Oscillator Frequency (MHz)
TH1 reload value
11.0592
14.7456
18.432
22.1184
36.864
Baud Rate
9600
FDh
FCh
FBh
FAh
F6h
4800
FAh
F8h
F6h
F4h
ECh
2400
F4h
F0h
ECh
E8h
D8h
1200
E8h
E0h
D8h
D0h
B0h
300
A0h
80h
60h
40h
Table 13–4. Timer 2 Generated Commonly Used Baud Rates
RCAP2H, RCAP2L
reload value
Oscillator Frequency (MHz)
11.0592
14.7456
18.432
22.1184
36.864
Baud Rate
115200
FFh, FDh
FFh, FCh
FFh, FBh
FFh, FAh
FFh, F6h
57600
FFh, FAh
FFh, F8h
FFh, F6h
FFh, F4h
FFh, ECh
38400
FFh, F7h
FFh, F4h
FFh, F1h
FFh, EEh
FFh, E2h
19200
FFh, EEh
FFh, E8h
FFh, E2h
FFh, DCh
FFh, C4h
9600
FFh, DCh
FFh, D0h
FFh, C4h
FFh, B8h
FFh, 88h
4800
FFh, B8h
FFh, A0h
FFh, 88h
FFh, 70h
FFh, 10h
2400
FFh, 70h
FFh, 40h
FFh, 10h
FEh, E0h
FEh, 20h
1200
FEh, E0h
FEh, 80h
FEh, 20h
FDh, C0h
FCh, 40h
300
FBh, 80h
FAh, 00h
F8h, 80h
F7h, 00h
F1h, 00h
13.6 Multiprocessor Communication
N78E517A multiprocessor communication feature of UART lets a Master device send a multiple frame serial
message to a Slave device in a multi-slave configuration. It does this without interrupting other slave devices
that may be on the same serial line. This feature can be used only in UART mode 2 or 3 mode. After 9 data
th
bits are received. The 9 bit value is written to RB8 (SCON.2). The user can enable this function by setting
SM2 (SCON.5) as a logic 1 so that when the stop bit is received, the serial interrupt will be generated only if
th
RB8 is 1. When the SM2 bit is 1, serial data frames that are received with the 9 bit as 0 do not generate an
th
interrupt. In this case, the 9 bit simply separates the address from the serial data.
When the Master device wants to transmit a block of data to one of several slaves on a serial line, it first sends
out an address byte to identify the target slave. Note that in this case, an address byte differs from a data byte:
th
In an address byte, the 9 bit is 1 and in a data byte, it is 0. The address byte interrupts all slaves so that each
slave can examine the received byte and see if it is being addressed. The addressed slave then clears its SM2
- 64 -
bit and prepares to receive incoming data bytes. The SM2 bits of slaves that were not addressed remain set,
and they continue operating normally while ignoring the incoming data bytes.
Follow these steps to configure multiprocessor communications.
1. Set all devices (Masters and Slaves) to UART mode 2 or 3.
2. Write the SM2 bit of all the Slave devices to 1.
3. The Master device‟s transmission protocol is:
th
– First byte: the address, identifying the target slave device, (9 bit = 1).
th
– Next bytes: data, (9 bit = 0).
th
4. When the target Slave receives the first byte, all of the Slaves are interrupted because the 9 data bit is 1.
The targeted Slave compares the address byte to its own address and then clears its SM2 bit in order to receive incoming data. The other slaves continue operating normally.
5. After all data bytes have been received, set SM2 back to 1 to wait for next address.
SM2 has no effect in Mode 0, and in Mode 1 can be used to check the validity of the stop bit. For mode 1 reception, if SM2 is 1, the receive interrupt will not be issue unless a valid stop bit is received.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
14. SERIAL PERIPHERAL INTERFACE (SPI)
14.1 Features
N78E517A exists a Serial Peripheral Interface (SPI) block to support high speed serial communication. SPI is a
full-duplex, high speed, synchronous communication bus between MCUs or other peripheral devices such as
serial EEPROM, LCD driver, or D/A converter. It provides either Master or Slave mode, high speed rate up to
FPERIPH/16 for Master mode and FPERIPH/4 for Slave mode, transfer complete and write collision flag. For a multimaster system, SPI supports Master Mode Fault to protect a multi-master conflict.
14.2 Functional Description
FPERIPH
S
M
MSB
Select
M
S
CLOCK
SPR0
SPR1
LSB
8-bit Shift Register
Read Data Buffer
MISO
MOSI
Pin Contorl Logic
Divider
/16, /32, /64, /128
Clock Logic
SPCLK
MSTR
SPI Status Register
SPI Interrupt
Request
SPR1
SPR0
CPHA
CPOL
LSBFE
MSTR
SSOE
SPIEN
DISMODF
MODF
SPIOVF
WCOL
SPIF
SPI Status Control Logic
SPIEN
SPI Control Register
Internal
Data Bus
Figure 14–1. SPI Block Diagram
- 66 -
SSOE
DISMODF
SPIEN
MSTR
SS
Figure 14–1 shows SPI block diagram. It provides an overview of SPI architecture in this device. The main
blocks of SPI are the SPI control register logic, SPI status logic, clock rate control logic, and pin control logic.
For a serial data transfer or receiving, The SPI block exists a shift register and a read data buffer. It is single
buffered in the transmit direction and double buffered in the receiving direction. Transmit data cannot be written
to the shifter until the previous transfer is complete. Receiving logic consists of parallel read data buffer so the
shift register is free to accept a second data, as the first received data will be transferred to the read data buffer.
The four pins of SPI interface are Master-In/Slave-Out (MISO), Master-Out/Slave-In (MOSI), Shift Clock
(SPCLK), and Slave Select ( SS ). The MOSI pin is used to transfer a 8-bit data in series from the Master to the
Slave. Therefore, MOSI is an output pin for Master device and a input for Slave. Respectively, the MISO is
used to receive a serial data from the Slave to the Master.
The SPCLK pin is the clock output in Master mode, but is the clock input in Slave mode. The shift clock is used
to synchronize the data movement both in and out of the devices through their MOSI and MISO pins. The shift
clock is driven by the Master mode device for eight clock cycles which exchanges one byte data on the serial
lines. For the shift clock is always produced out of the Master device, the system should never exist more than
one device in Master mode for avoiding device conflict.
Each Slave peripheral is selected by one Slave Select pin ( SS ). The signal must stay low for any Slave access. When SS is driven high, the Slave device will be inactivated. If the system is multi-slave, there should be
only one Slave device selected at the same time. In the Master mode MCU, the SS pin does not function and
it can be configured as a general purpose I/O. However, SS can be used as Master Mode Fault detection (see
Section 14.7 “Mode Fault Detection” on page 75) via software setting if multi-master environment exists.
N78E517A also provides auto-activating function to toggle SS between each byte-transfer.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Master/Slave
MCU1
Master/Slave
MCU2
MISO
MISO
MOSI
MOSI
SPCLK
Slave device 1
Slave device 2
I/O
PORT
SO
SI
SCK
SS
SO
SI
SCK
SS
0
1
2
3
SO
0
1
2
3
SI
SS
SCK
SS
SS
I/O
PORT
SPCLK
Slave device 3
Figure 14–2. SPI Multi-master, Multi-slave Interconnection
Figure 14–2 shows a typical interconnection of SPI devices. The bus generally connects devices together
through three signal wires, MOSI to MOSI, MISO to MISO, and SPCLK to SPCLK. The Master devices select
the individual Slave devices by using four pins of a parallel port to control the four SS pins. MCU1 and MCU2
play either Master or Slave mode. The SS should be configured as Master Mode Fault detection to avoid multi-master conflict.
MOSI
MOSI
MISO
MISO
SPI shift register
7 6 5 4 3 2 1 0
SPI shift register
7 6 5 4 3 2 1 0
SPCLK SPCLK
SPI clock
generator
SS
Master MCU
SS
*
VSS
Slave MCU
* SS configuration follows DISMODF and SSOE bits.
Figure 14–3. SPI Single-master, Single-slave Interconnection
Figure 14–3 shows the simplest SPI system interconnection, single-master and signal-slave. During a transfer,
the Master shifts data out to the Slave via MOSI line. While simultaneously, the Master shifts data in from the
Slave via MISO line. The two shift registers in the Master MCU and the Slave MCU can be considered as one
16-bit circular shift register. Therefore, while a transfer data pushed from Master into Slave, the data in Slave
will also be pulled in Master device respectively. The transfer effectively exchanges the data which was in the
SPI shift registers of the two MCUs.
- 68 -
By default, SPI data is transferred MSB first. If the LSBFE (SPCR.5) is set, SPI data shifts LSB first. This bit
does not affect the position of the MSB and LSB in the data register. Note that all following description and figures are under the condition of LSBFE logic 0. MSB is transmitted and received first.
14.3 Control Registers of SPI
There are three SPI registers to support its operations, they are SPI control register (SPCR), SPI status register (SPSR), and SPI data register (SPDR). These registers provide control, status, data storage functions, and
clock rate selection. The following registers relate to SPI function.
SPCR – Serial Peripheral Control Register
7
6
5
4
SSOE
SPIEN
LSBFE
MSTR
r/w
r/w
r/w
r/w
Address: F3H
3
CPOL
r/w
2
CPHA
r/w
1
0
SPR1
SPR0
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7
SSOE
Slave select output enable.
This bit is used in combination with the DISMODF (SPSR.3) bit to determine the
feature of SS pin as shown in Table 14–1. Slave Select Pin Configurations. This
bit takes effect only under MSTR = 1 and DISMODF = 1 condition.
0 = SS functions as a general purpose I/O pin.
1 = SS automatically goes low for each transmission when selecting external
Slave device and goes high during each idle state to de-select the Slave device.
6
SPIEN
SPI enable.
0 = Disable SPI function.
1 = Enable SPI function.
5
LSBFE
LSB first enable.
0 = The SPI data is transferred MSB first.
1 = The SPI data is transferred LSB first.
4
MSTR
Master mode enable.
This bit switches the SPI operating between Master and Slave modes.
0 = The SPI is configured as Slave mode.
1 = The SPI is configured as Master mode.
3
CPOL
SPI clock polarity select.
CPOL bit determines the idle state level of the SPI clock. See Figure 14–4. SPI
Clock Formats.
0 = The SPI clock is low in idle state.
1 = The SPI clock is high in idle state.
2
CPHA
SPI clock phase select.
CPHA bit determines the data sampling edge of the SPI clock. See Figure 14–4.
SPI Clock Formats.
0 = The data is sampled on the first edge of the SPI clock.
1 = The data is sampled on the second edge of the SPI clock.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Bit
Name
1
SPR1
0
SPR0
Description
SPI clock rate select.
These two bits select four grades of SPI clock divider.
SPR1 SPR0 Divider SPI clock rate
0
0
16
1.25M bit/s
0
1
32
625k bit/s
1
0
64
312k bit/s
1
1
128
156k bit/s
The clock rates above are illustrated under FPERIPH = 20MHz condition.
Table 14–1. Slave Select Pin Configurations
DISMODF
SSOE
Master Mode (MSTR = 1)
0
x
SS input for Mode Fault
1
0
General purpose I/O
1
1
Automatic SS output
Slave Mode (MSTR = 0)
SS Input for Slave select
SPSR – Serial Peripheral Status Register
7
6
5
4
SPIF
WCOL
SPIOVF
MODF
r/w
r/w
r/w
r/w
Address: F4H
3
DISMODF
r/w
2
-
1
0
reset value: 0000 0000b
Bit
Name
Description
7
SPIF
SPI complete flag.
This bit is set to logic 1 via hardware while an SPI data transfer is complete or an
receiving data has been moved into the SPI read buffer. If ESPI (EIE .0) and EA
are enabled, an SPI interrupt will be required. This bit must be cleared via software. Attempting to write to SPDR is inhibited if SPIF is set.
6
WCOL
Write collision error flag.
This bit indicates a write collision event. Once a write collision event occurs, this
bit will be set. It must be cleared via software.
5
SPIOVF
SPI overrun error flag.
This bit indicates an overrun event. Once an overrun event occurs, this bit will be
set. If ESPI and EA are enabled, an SPI interrupt will be required. This bit must
be cleared via software.
4
MODF
Mode Fault error flag.
This bit indicates a Mode Fault error event. If SS pin is configured as Mode
Fault input (MSTR = 1 and DISMODF = 0) and SS is pulled low by external devices, a Mode Fault error occurs. Instantly MODF will be set as logic 1. If ESPI
and EA are enabled, an SPI interrupt will be required. This bit must be cleared
via software.
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Bit
Name
Description
3
DISMODF
Disable Mode Fault error detection.
This bit is used in combination with the SSOE (SPCR.7) bit to determine the feature of SS pin as shown in Table 14–1. Slave Select Pin Configurations.
DISMODF affects only in Master mode (MSTR = 1).
0 = Mode Fault detection is not disabled. SS serves as input pin for Mode Fault
detection disregard of SSOE.
1 = Mode Fault detection is disabled. The feature of SS follows SSOE bit.
2:0
-
Reserved.
SPDR – Serial Peripheral Data Register
7
6
5
4
3
2
1
0
SPDR[7:0]
r/w
Address: F5H
reset value: 0000 0000b
Bit
Name
Description
7:0
SPDR[7:0]
Serial peripheral data.
This byte is used of transmitting or receiving data on SPI bus. A write of this byte
is a write to the shift register. A read of this byte is actually a read of the read
data buffer. In Master mode, a write to this register initiates transmission and
reception of a byte simultaneously.
14.4 Operating Modes
14.4.1 Master mode
The SPI can operate in Master mode while MSTR (SPCR.4) is set as 1. Only one Master SPI device can initiate transmissions. A transmission always begins by Master through writing to SPDR. The byte written to SPDR
begins shifting out on MOSI pin under the control of SPCLK. Simultaneously, another byte shifts in from the
Slave on the MISO pin. After 8-bit data transfer complete, SPIF (SPSR.7) will automatically set via hardware to
indicate one byte data transfer complete. At the same time, the data received from the Slave is also transferred
in SPDR. The user can clear SPIF and read data out of SPDR.
14.4.2 Slave Mode
When MSTR is 0, the SPI operates in Slave mode. The SPCLK pin becomes input and it will be clocked by
another Master SPI device. The SS pin also becomes input. The Master device cannot exchange data with
the Slave device until the SS pin of the Slave device is externally pulled low. Before data transmissions occurs, the SS of the Slave device must be pulled and remain low until the transmission is complete. If SS goes
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
high, the SPI is forced into idle state. If the SS is force to high at the middle of transmission, the transmission
will be aborted and the rest bits of the receiving shifter buffer will be high and goes into idle state.
In Slave mode, data flows from the Master to the Slave on MOSI pin and flows from the Slave to the Master on
MISO pin. The data enters the shift register under the control of the SPCLK from the Master device. After one
byte is received in the shift register, it is immediately moved into the read data buffer and the SPIF bit is set. A
read of the SPDR is actually a read of the read data buffer. To prevent an overrun and the loss of the byte that
caused by the overrun, the Slave must read SPDR out and the first SPIF must be cleared before a second
transfer of data from the Master device comes in the read data buffer.
14.5 Clock Formats and Data Transfer
To accommodate a wide variety of synchronous serial peripherals, the SPI has a clock polarity bit CPOL
(SPCR.3) and a clock phase bit CPHA (SPCR.2). Figure 14–4. SPI Clock Formats shows that CPOL and
CPHA compose four different clock formats. The CPOL bit denotes the SPCLK line level in SPI idle state. The
CPHA bit defines the edge on which the MOSI and MISO lines are sampled. The CPOL and CPHA should be
identical for the Master and Slave devices on the same system. To Communicate in different data formats with
one another will result undetermined result.
Clock Phase (CPHA)
CPOL = 0
CPHA = 1
sample
sample
sample
sample
CPOL = 1
Clock Polarity (CPOH)
CPHA = 0
Figure 14–4. SPI Clock Formats
In SPI, a Master device always initiates the transfer. If SPI is selected as Master mode (MSTR = 1) and enabled (SPIEN = 1), writing to the SPI data register (SPDR) by the Master device starts the SPI clock and data
transfer. After shifting one byte out and receiving one byte in, the SPI clock stops and SPIF (SPSR.7) is set in
both Master and Slave. If SPI interrupt enable bit ESPI (EIE.0) is set 1 and global interrupt is enabled (EA = 1),
the interrupt service routine (ISR) of SPI will be executed.
- 72 -
Concerning the Slave mode, the SS signal needs to be taken care. As shown in Figure 14–4. SPI Clock Formats, when CPHA = 0, the first SPCLK edge is the sampling strobe of MSB (for an example of LSBFE = 0,
MSB first). Therefore, the Slave must shift its MSB data before the first SPCLK edge. The falling edge of SS is
used for preparing the MSB on MISO line. The SS pin therefore must toggle high and then low between each
successive serial byte. Furthermore, if the slave writes data to the SPI data register (SPDR) while SS is low, a
write collision error occurs.
When CPHA = 1, the sampling edge thus locates on the second edge of SPCLK clock. The Slave uses the first
SPCLK clock to shift MSB out rather than the SS falling edge. Therefore, the SS line can remain low between
successive transfers. This format may be preferred in systems having single fixed Master and single fixed
Slave. The SS line of the unique Slave device can be tied to VSS as long as only CPHA = 1 clock mode is
used.
Note: The SPI should be configured before it is enabled (SPIEN = 1), or a change of LSBFE, MSTR,
CPOL, CPHA and SPR[1:0] will abort a transmission in progress and force the SPI system into idle
state. Prior to any configuration bit changed, SPIEN must be disabled first.
SPCLK Cycles
1
SPCLK Cycles
2
3
4
5
6
7
8
SPCLK (CPOL=0)
SPCLK (CPOL=1)
Transfer Progress[1]
(internal signal)
MOSI
MISO
MSB
MSB
6
5
4
3
2
1
6
5
4
3
2
1
LSB
LSB
Input to Slave SS
SS output of Master[2]
SPIF (Master)
SPIF (Slave)
[1] Transfer progress starts by a writing SPDR of Master MCU.
[2] SS automatic output affects when MSTR = DISMODF = SSOE = 1.
Figure 14–5. SPI Clock and Data Format with CPHA = 0
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
SPCLK Cycles
SPCLK Cycles
1
2
3
4
5
6
7
8
MSB
6
5
4
3
2
1
LSB
6
5
4
3
2
1
SPCLK (CPOL=0)
SPCLK (CPOL=1)
Transfer Progress[1]
(internal signal)
MOSI
MSB
MISO
LSB
[3]
[4]
Input to Slave SS
SS output of Master[2]
SPIF (Master)
SPIF (Slave)
[1] Transfer progress starts by a writing SPDR of Master MCU.
[2] SS automatic output affects when DISMODF = SSOE = MSTR = 1.
[3] If SS of Slave is low, the MISO will be the LSB of previous data. Otherwise, MISO will be high.
[4] While SS stays low, the LSB will last its state. Once SS is released to high, MISO will switch to high level.
Figure 14–6. SPI Clock and Data Format with CPHA = 1
14.6 Slave Select Pin Configuration
N78E517A SPI gives a flexible SS pin feature for different system requirements. When the SPI operates as a
Slave, SS pin always rules as Slave select input. When the Master mode is enabled, SS has three different
functions according to DISMODF (SPSR.3) and SSOE (SPCR.7). By default, DISMODF is 0. It means that the
Mode Fault detection activates. SS is configured as a input pin to check if the Mode Fault appears. On the
contrary, if DISMODF is 1, Mode Fault is inactivated and the SSOE bit takes over to control the function of the
SS pin. While SSOE is 1, it means the Slave select signal will generate automatically to select a Slave device.
The SS as output pin of the Master usually connects with the SS input pin of the Slave device. The SS output automatically goes low for each transmission when selecting external Slave device and goes high during
each idle state to de-select the Slave device. While SSOE is 0 and DISMODF is 1, SS is no more used by the
SPI and reverts to be a general purpose I/O pin.
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14.7 Mode Fault Detection
The Mode Fault detection is useful in a system where more than one SPI devices might become Masters at the
same time. It may induce data contention. When the SPI device is configured as a Master and the SS input
line is configured for Mode Fault input depending on Table 14–1. Slave Select Pin Configurations, a Mode
Fault error occurs once the SS is pulled low by others. It indicates that some other SPI device is trying to address this Master as if it is a Slave. Instantly the MSTR and SPIEN control bits in the SPCR are cleared via
hardware to disable SPI, Mode Fault flag MODF (SPSR.4) is set and an interrupt is generated if ESPI (EIE .0)
and EA are enabled.
14.8 Write Collision Error
The SPI is signal buffered in the transfer direction and double buffered in the receiving direction. New data for
transmission cannot be written to the shift register until the previous transaction is complete. Write collision
occurs while an attempt was made to write data to the SPDR while a transfer was in progress. SPDR is not
double buffered in the transmit direction. Any writing to SPDR cause data to be written directly into the SPI shift
register. Once a write collision error is generated, WCOL (SPSR.6) will be set as a 1 via hardware to indicate a
write collision. In this case, the current transferring data continues its transmission. However the new data that
caused the collision will be lost. Although the SPI logic can detect write collisions in both Master and Slave
modes, a write collision is normally a Slave error because a Slave has no indicator when a Master initiates a
transfer. During the receive of Slave, a write to SPDR causes a write collision in Slave mode. WCOL flag
needs to be cleared via software.
14.9 Overrun Error
For receiving data, the SPI is double buffered in the receiving direction. The received data is transferred into a
parallel read data buffer so the shifter is free to accept a second serial byte. However, the received data must
be read from SPDR before the next data has been completely shifted in. As long as the first byte is read out of
the read data buffer and SPIF is cleared before the next byte is ready to be transferred, no overrun error condition occurs. Otherwise the overrun error occurs. In this condition, the second byte data will not be successfully
received into the read data register and the previous data will remains. If overrun occur, SPIOVF (SPSR.5) will
be set via hardware. An SPIOVF setting will also require an interrupt if enabled. Figure 14–7. SPI Overrun
Waveform shows the relationship between the data receiving and the overrun error.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Data[n] Receiving Begins
Shift Register
Data[n+1] Receiving Begins
Shifting Data[n] in
SPIF
Data[n+2] Receiveing Begins
Shifting Data[n+1] in
Shifting Data[n+2] in
[1]
[3]
Read Data Buffer
Data[n]
SPIOVF
[4]
Data[n]
[2]
Data[n+2]
[3]
[1] When Data[n] is received, the SPIF will be set.
[2] If SPIF is not clear before Data[n+1] progress done, the SPIOVF will
be set. Data[n] will be kept in read data buffer but Data [n+1] will be lost.
[3] SPIF and SPIOVF must be cleared by software.
[4] When Data[n+2] is received, the SPIF will be set again.
Figure 14–7. SPI Overrun Waveform
14.10 SPI Interrupts
Three SPI status flags, SPIF, MODF, and SPIOVF, can generate an SPI event interrupt requests. All of them
locate in SPSR. SPIF will be set after completion of data transfer with external device or a new data have been
received and copied to SPDR. MODF becomes set to indicate a low level on SS causing the Mode Fault state.
SPIOVF denotes a receiving overrun error. If SPI interrupt mask is enabled via setting ESPI (EIE.0) and EA is
1, CPU will executes the SPI interrupt service routine once any of these three flags is set. The user needs to
check flags to determine what event caused the interrupt. These three flags are software cleared.
SPIF
SPIOVF
SS
MSTR
DISMODF
Mode
MODF
Fault
Detection
SPI Interrupt
Request
ESPI
(EIE.0)
EA
Figure 14–8. SPI Interrupt Request
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15. PULSE WIDTH MODULATOR (PWM)
N78E517A provides five pulse width modulated (PWM) output channels to generate pulses of programmable
length and interval. Five PWM channels, PWM0-4, shares the same pins with P1.3-P1.7. The PWM period is
defined by an 8-bit pre-scalar PWMP, which supplies the clock of the PWM counter. The pre-scalar is common
for all PWM channels. The duty of each PWM channel is determined by the value of five registers, PWM0,
PWM1, PWM2, PWM3, and PWM4. If the contents of these registers are equal to or less than the 8-bit counter
value, the output will be 0. Else the output will be 1 if these registers value are larger than the counter. Set
PWMxEN (in PWMCON0[0,1,4,5] and PWMCON1.0) will enable to run or disable to stop each PWM channel
respectively. In addition, the PWMxOM (in PWMCON0[2,3,6,7] and PWMCON1.2) must set 1 to output the
internal PWM signal to port pins. Without setting PWMxOM, the pins which share with alternative PWM function will be normal general purpose I/O of P1.3-P1.7 even though PWM is enabled. The following registers relate to PWM function.
PWMCON0 – PWM Control 0
7
6
5
PWM3OE
PWM2OE
PWM3EN
r/w
r/w
r/w
Address: DCH
4
PWM2EN
r/w
3
PWM1OE
r/w
Bit
Name
7
PWM3OE
PWM3 output enable.
0 = P1.6 serves as general purpose I/O.
1 = P1.6 serves as output pin of PWM3 signal.
6
PWM2OE
PWM2 output enable.
0 = P1.5 serves as general purpose I/O.
1 = P1.5 serves as output pin of PWM2 signal.
5
PWM3EN
PWM3 enable.
0 = PWM3 is disabled and stops.
1 = PWM3 is enabled and runs.
4
PWM2EN
PWM2 enable.
0 = PWM2 is disabled and stops.
1 = PWM2 is enabled and runs.
3
PWM1OE
PWM1 output enable.
0 = P1.4 serves as general purpose I/O.
1 = P1.4 serves as output pin of PWM1 signal.
2
PWM0OE
PWM0 output enable.
0 = P1.3 serves as general purpose I/O.
1 = P1.3 serves as output pin of PWM0 signal.
1
PWM1EN
PWM1 enable.
0 = PWM1 is disabled and stops.
1 = PWM1 is enabled and runs.
2
PWM0OE
r/w
1
0
PWM1EN
PWM0EN
r/w
r/w
reset value: 0000 0000b
Description
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Bit
Name
0
PWM0EN
Description
PWM0 enable.
0 = PWM0 is disabled and stops.
1 = PWM0 is enabled and runs.
PWMCON1 – PWM Control 1
7
6
Address: CEH
Bit
Name
7:3
-
2
PWM4OE
1
-
0
PWM4EN
PWMP – PWM Period
7
6
5
-
4
-
3
-
2
PWM4OE
r/w
1
0
PWM4EN
r/w
reset value: 0000 0000b
Description
Reserved.
PWM4 output enable.
0 = P1.7 serves as general purpose I/O.
1 = P1.7 serves as output pin of PWM4 signal.
Reserved.
PWM0 enable.
0 = PWM4 is disabled and stops.
1 = PWM4 is enabled and runs.
5
4
3
2
1
0
PWMP[7:0]
r/w
Address: D9H
reset value: 0000 0000b
Bit
Name
7:0
PWMP[7:0]
PWM0 – PWM0 Duty
7
6
Description
PWM period.
This byte controls the period of the PWM output of PWM0-PWM4 channels.
5
4
3
2
1
0
PWM0[7:0]
r/w
Address: DAH
reset value: 0000 0000b
Bit
Name
7:0
PWM0[7:0]
Description
PWM0 duty.
This byte controls the duty of the PWM0 output.
- 78 -
PWM1 – PWM1 Duty
7
6
5
4
3
2
1
0
PWM1[7:0]
r/w
Address: DBH
reset value: 0000 0000b
Bit
Name
7:0
PWM1[7:0]
PWM2 – PWM2 Duty
7
6
Description
PWM1 duty.
This byte controls the duty of the PWM1 output.
5
4
3
2
1
0
PWM2[7:0]
r/w
Address: DDH
reset value: 0000 0000b
Bit
Name
7:0
PWM2[7:0]
PWM3 – PWM3 Duty
7
6
Description
PWM2 duty.
This byte controls the duty of the PWM2 output.
5
4
3
2
1
0
PWM3[7:0]
r/w
Address: DEH
reset value: 0000 0000b
Bit
Name
7:0
PWM3[7:0]
PWM4 – PWM4 Duty
7
6
Description
PWM3 duty.
This byte controls the duty of the PWM3 output.
5
4
3
2
1
0
PWM4[7:0]
r/w
Address: CFH
reset value: 0000 0000b
Bit
Name
7:0
PWM4[7:0]
Description
PWM4 duty.
This byte controls the duty of the PWM4 output.
The repetition frequency of PWM, FPWM is given by,
FPWM
FPERIPH
, pre-scalar division factor = PWM + 1.
(PWMP 1) 255
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
PWM high duty of PWMx =
PWMx
.
255
PWMP gives a repetition frequency range of 122Hz to 31.25kHz (FPERIPH = 16MHz). By loading the PWMx registers with either 00H or FFH, the PWM channels will generate a constant low or high level output, respectively.
When a compare register PWMx is loaded with a new value, the associated output updated immediately. It
does not have to wait until the end of the current counter period.
FPERIPH
Pre-scalar
PWMP
8-bit
Up-counter
PWM0
PWM0EN
+
-
PWM0OE
PWM0 (P1.3)
PWM1EN
PWM1
+
-
PWM1OE
PWM1 (P1.4)
PWM2EN
PWM2
+
-
PWM2OE
PWM2 (P1.5)
PWM3EN
PWM3
+
-
PWM3OE
PWM3 (P1.6)
PWM4EN
PWM4
+
-
PWM4OE
Figure 15–1. PWM Function Block
PWM demo code,
MOV
MOV
MOV
MOV
MOV
MOV
ORL
ORL
ORL
ORL
PWMP,#128
PWM0,#0H
PWM1,#40H
PWM2,#80H
PWM3,#0C0H
PWM4,#0FFH
PWMCON0,#00110011b
PWMCON1,#00000001b
PWMCON0,#11001100b
PWMCON1,#00000100b
;determine PWM period
;duty = 0%
;duty = 25%
;duty = 50%
;duty = 75%
;duty = 100%
;enable PWM0-3
;enable PWM4
;output enable PWM0-3
;output enable PWM4
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PWM4 (P1.7)
16. TIMED ACCESS PROTECTION (TA)
N78E517A has several features like the Watchdog Timer, the ISP function, Boot select control, etc. are crucial
to proper operation of the system. If leaving these control registers unprotected, errant code may write undetermined value into them, it results in incorrect operation and loss of control. In order to prevent this risk, the
N78E517A has a protection scheme which limits the write access to critical SFRs. This protection scheme is
done using a timed access. The following registers are related to TA process.
TA – Timed Access
7
6
5
4
3
2
1
0
TA[7:0]
w
Address: C7H
reset value: 0000 0000b
Bit
Name
Description
7:0
TA[7:0]
Timed access.
The timed access register controls the access to protected SFRs. To access protected bits, the user must first write AAH to the TA and immediately followed by a
write of 55H to TA. After these two steps, a writing permission window is opened
for three machine-cycles during which the user may write to protected SFRs.
In timed access method, the bits, which are protected, have a timed write enable window. A write is successful
only if this window is active; otherwise, the write will be discarded. When the software writes AAH to TA, a
counter is started. This counter waits for three machine-cycles looking for a write of 55H to TA. If the second
write of 55H occurs within three machine-cycles of the first write of AAH, then the timed access window is
opened. It remains open for three machine-cycles during which the user may write to the protected bits. After
three machine-cycles, this window automatically closes. Once the window closes, the procedure must be repeated to access the other protected bits. Not that the TA protected SFRs are required timed access for writing. But the reading is not protected. The user may read TA protected SFR without giving AAH and 55H to TA.
The suggestion code for opening the timed access window is shown below.
(CLR
EA)
;if any interrupt is enabled, disable temporally
MOV
TA,#0AAH
MOV
TA,#55H
(Instruction that writes a TA protected register)
(SETB
EA)
;resume interrupts enabled
The writings of AAH, 55H to TA register and the writing-protection register must occur within 3 machine-cycles
of each other. Any enabled interrupt should be disabled during this procedure to avoid delay between these
three writings. If there is no interrupt enabled, the CLR EA and SETB EA instructions can be left out. Once the
timed access window closes, the procedure must be repeated to access the other protected bits.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Examples of timed assessing are shown to illustrate correct or incorrect writing processes.
Example 1,
MOV
MOV
ORL
TA,#0AAH
TA,#55H
CHPCON,#data
;2 machine-cycles.
;2 machine-cycles.
;2 machine-cycles.
TA,#0AAH
TA,#55H
;2
;2
;1
;1
;2
machine-cycles.
machine-cycles.
machine-cycle.
machine-cycle.
machine-cycles.
;2
;1
;2
;2
;2
machine-cycles.
machine-cycle.
machine-cycles.
machine-cycles.
machine-cycles.
;2
;1
;1
;2
;2
machine-cycles.
machine-cycle.
machine-cycle.
machine-cycles.
machine-cycles.
Example 2,
MOV
MOV
NOP
NOP
ANL
ISPTRG,#data
Example 3,
MOV
NOP
MOV
MOV
ORL
TA,#0AAH
TA,#55H
WDCON,#data1
PMC,#data2
Example 4,
MOV
NOP
NOP
MOV
ANL
TA,#0AAH
TA,#55H
WDCON,#data
In the first examples, the writing to the protected bits is done before the three-machine-cycle window closes. In
example 2, however, the writing to ISPTRG does not complete during the window opening, there will be no
change of the value of ISPTRG. In example 3, the WDCON is successful written but the PMC access is out of
the three-machine-cycle window. Therefore PMC value will not change either. In Example 4, the second write
55H to TA completes after three machine-cycles of the first write TA of AAH, therefore the timed access window in not opened at all, and the write to the protected bit fails.
In N78E517A, the TA protected SFRs includes CHPCON (9FH), ISPTRG (A4H), PMC (ACH), SHBDA (9CH),
and WDCON (AAH).
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17. INTERRUPT SYSTEM
The purpose of the interrupt is to make the software deal with unscheduled or asynchronous events.
N78E517A has a four-priority-level interrupt structure with 11 interrupt sources. Each of the interrupt sources
has an individual priority bit, flag, interrupt vector and enable bit. In addition, the interrupts can be globally enabled or disabled. When an interrupt occurs, the CPU is expected to service the interrupt. This service is specified as an Interrupt Service Routine (ISR). The ISR resides at a predetermined address as shown in Table 17–
1. N78E517A Interrupt Vectors. When the interrupt occurs if enabled, the CPU will vector to the appropriate
location, execute the code at this location, and stay in an interrupt service state until the ISR is done. Once an
ISR has begun, it can be interrupted only by a higher priority interrupt. The ISR is terminated by a return from
interrupt instruction RETI. This instruction will force the CPU return to the instruction that would have been next
when the interrupt occurred.
Table 17–1. N78E517A Interrupt Vectors
Vector
Address
Vector
Number
Vector
Address
Vector
Number
External Interrupt 0
0003H
0
Timer 0 Overflow
000BH
1
External Interrupt 1
0013H
2
Timer 1 Overflow
001BH
3
Serial Port Interrupt
0023H
4
Timer 2 Overflow/Capture/Reload
002BH
5
External Interrupt 2
0033H
6
External Interrupt 3
003BH
7
SPI Interrupt
0043H
8
Power Down Waking-up Timer
Interrupt
004BH
9
Brown-out Detection Interrupt
0053H
10
Source
Source
The SFRs associated with these interrupts are listed below.
IE – Interrupt Enable (bit-addressable)
7
6
5
EA
ET2
r/w
r/w
Address: A8H
4
ES
r/w
3
ET1
r/w
2
EX1
r/w
1
0
ET0
EX0
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7
EA
Enable all interrupt.
This bit globally enables/disables all interrupts. It overrides the individual interrupt
mask settings.
0 = Disable all interrupt sources.
1 = Enable each interrupt depending on its individual mask setting. Individual interrupts will occur if enabled.
6
-
Reserved.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Bit
Name
Description
5
ET2
Enable Timer 2 interrupt.
0 = Disable all Timer 2 interrupts.
1 = Enable interrupt generated by TF2 (T2CON.7) or EXF2 (T2CON.6).
4
ES
Enable serial port (UART) interrupt.
0 = Disable all UART interrupts.
1 = Enable interrupt generated by TI (SCON.1) or RI (SCON.0).
3
ET1
Enable Timer 1 interrupt.
0 = Disable Timer 1 interrupt
1 = Enable interrupt generated by TF1 (TCON.7).
2
EX1
Enable external interrupt 1.
0 = Disable external interrupt 1.
1 = Enable interrupt generated by INT1 pin (P3.3).
1
ET0
Enable Timer 0 interrupt.
0 = Disable Timer 0 interrupt
1 = Enable interrupt generated by TF0 (TCON.5).
0
EX0
Enable external interrupt 0.
0 = Disable external interrupt 0.
1 = Enable interrupt generated by INT0 pin (P3.2).
EIE – Extensive Interrupt Enable
7
6
5
Address: BDH
4
-
3
-
2
EBOD
r/w
1
0
EPDT
ESPI
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7:3
-
2
EBOD
Enable Brown-out detection interrupt.
0 = Disable Brown-out detection interrupt.
1 = Enable interrupt generated by BOF (PMC.3).
1
EPDT
Enable Power Down waking-up timer interrupt.
0 = Disable Power Down waking-up timer interrupt
1 = Enable interrupt generated by PDTF (PDCON.5).
0
ESPI
Enable SPI interrupt.
0 = Disable SPI interrupt.
1 = Enable interrupt generated by SPIF (SPSR.7), SPIOVF (SPSR.5), or MODF
(SPSR.4).
Reserved.
IP – Interrupt Priority (bit-addressable)[1]
7
6
5
PT2
r/w
Address: B8H
Bit
Name
7:6
-
5
PT2
4
PS
r/w
3
PT1
r/w
Description
Reserved.
Timer 2 interrupt priority low bit.
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2
PX1
r/w
1
0
PT0
PX0
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
4
PS
Serial port (UART) interrupt priority low bit.
3
PT1
Timer 1 interrupt priority low bit.
2
PX1
External interrupt 1 priority low bit.
1
PT0
Timer 0 interrupt priority low bit.
External interrupt 0 priority low bit.
0
PX0
[1] IP is used in combination with the IPH to determine the priority of each interrupt source. See Table 17–2. Interrupt Priority Level Setting for correct interrupt priority configuration.
IPH – Interrupt Priority High
7
6
5
PX3H[2]
PX2H[2]
PT2H[3]
r/w
r/w
r/w
Address: BAH
4
PSH[3]
r/w
3
PT1H[3]
r/w
Bit
Name
7
PX3H
External interrupt 3 priority high bit.
6
PX2H
External interrupt 3 priority high bit.
5
PT2H
Timer 2 interrupt priority high bit.
4
PSH
Serial port (UART) interrupt priority high bit.
3
PT1H
Timer 1 interrupt priority high bit.
2
PX1H
External interrupt 1 priority high bit.
1
PT0H
Timer 0 interrupt priority high bit.
2
PX1H[3]
r/w
1
0
PT0H[3]
PX0H[3]
r/w
r/w
reset value: 0000 0000b
Description
External interrupt 0 priority high bit.
0
PX0H
[2] PX2H and PX3H are used in combination with the PX2 (XICON.3) and PX3 (XICON.7) respectively to determine the
priority of external interrupt 2 and 3. See Table 17–2. Interrupt Priority Level Setting for correct interrupt priority configuration.
[3] These bits is used in combination with the IP respectively to determine the priority of each interrupt source. See Table
17–2. Interrupt Priority Level Setting for correct interrupt priority configuration.
EIP – Extensive Interrupt Priority[4]
7
6
5
Address: BCH
4
-
3
-
2
PBOD
r/w
Bit
Name
7:3
-
2
PBOD
Brown-out detection interrupt priority low bit.
1
PPDT
Power Down waking-up timer interrupt priority low bit.
1
0
PPDT
PSPI
r/w
r/w
reset value: 0000 0000b
Description
Reserved.
SPI interrupt priority low bit.
0
PSPI
[4] EIP is used in combination with the EIPH to determine the priority of each interrupt source. See Table 17–2. Interrupt
Priority Level Setting for correct interrupt priority configuration.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
EIPH – Extensive Interrupt Priority High[1]
7
6
5
Address: BBH
4
-
3
-
2
PBODH
r/w
Bit
Name
7:3
-
2
PBODH
Brown-out detection interrupt priority high bit.
1
PPDTH
Power Down waking-up timer interrupt priority high bit.
1
0
PPDTH
PSPIH
r/w
r/w
reset value: 0000 0000b
Description
Reserved.
SPI interrupt priority high bit.
0
PSPIH
[1] EIPH is used in combination with the EIP to determine the priority of each interrupt source. See Table 17–2. Interrupt
Priority Level Setting for correct interrupt priority configuration.
TCON – Timer 0 and 1 Control (bit-addressable)
7
6
5
4
TF1
TR1
TF0
TR0
r/w
r/w
r/w
r/w
Address: 88H
3
IE1
r/w
2
IT1
r/w
1
0
IE0
IT0
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
3
IE1
External interrupt 1 edge flag.
This flag is set via hardware when an edge/level of type defined by IT1 is detected. If IT1 = 1, this bit will remain set until cleared via software or at the beginning
of the External Interrupt 1 service routine. If IT1 = 0, this flag is the inverse of the
INT1 input signal‟s logic level.
2
IT1
External interrupt 1 type select.
This bit selects whether the INT1 pin will detect falling edge or low level triggered
interrupts.
0 = INT1 is low level triggered.
1 = INT1 is falling edge triggered.
1
IE0
External interrupt 0 edge flag.
This flag is set via hardware when an edge/level of type defined by IT0 is detected. If IT0 = 1, this bit will remain set until cleared via software or at the beginning
of the External Interrupt 0 service routine. If IT0 = 0, this flag is the inverse of the
INT0 input signal‟s logic level.
0
IT0
External interrupt 0 type select.
This bit selects whether the INT0 pin will detect falling edge or low level triggered
interrupts.
0 = INT0 is low level triggered.
1 = INT0 is falling edge triggered.
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XICON – External Interrupt Control (bit-addressable)
7
6
5
4
[1]
PX3
EX3
IE3
IT3
r/w
r/w
r/w
r/w
Address: C0H
3
PX2[1]
r/w
2
EX2
r/w
1
0
IE2
IT2
r/w
r/w
reset value: 0000 0000b
Bit
Name
Description
7
PX3
External interrupt 3 priority low bit.
6
EX3
Enable external interrupt 3.
0 = Disable external interrupt 3.
1 = Enable interrupt generated by INT3 pin (P4.2).
5
IE3
External interrupt 3 edge flag.
This flag is set via hardware when an edge/level of type defined by IT3 is detected. If IT3 = 1, this bit will remain set until cleared via software or at the beginning
of the External Interrupt 3 service routine. If IT3 = 0, this flag is the inverse of the
INT3 input signal‟s logic level.
4
IT3
External interrupt 3 type select.
This bit selects whether the INT3 pin will detect falling edge or low level triggered
interrupts.
0 = INT3 is low level triggered.
1 = INT3 is falling edge triggered.
3
PX2
External interrupt 2 priority low bit.
2
EX2
Enable external interrupt 2.
0 = Disable external interrupt 2.
1 = Enable interrupt generated by INT2 pin (P4.3).
1
IE2
External interrupt 2 edge flag.
This flag is set via hardware when an edge/level of type defined by IT2 is detected. If IT2 = 1, this bit will remain set until cleared via software or at the beginning
of the External Interrupt 2 service routine. If IT2 = 0, this flag is the inverse of the
INT2 input signal‟s logic level.
External interrupt 2 type select.
This bit selects whether the INT2 pin will detect falling edge or low level triggered
interrupts.
0 = INT2 is low level triggered.
1 = INT2 is falling edge triggered.
[1] PX2 and PX3 are used in combination with the PX2H (IPH.6) and PX3H (IPH.7) respectively to determine the priority of
external interrupt 2 and 3. See Table 17–2. Interrupt Priority Level Setting for correct interrupt priority configuration.
0
IT2
The External Interrupts INT0 and INT1 can be either edge or level triggered depending on bits IT0 (TCON.0)
and IT1 (TCON.2). The bits IE0 (TCON.1) and IE1 (TCON.3) are the flags which are checked to generate the
interrupt. In the edge triggered mode, the INT0 or INT1 inputs are sampled in every machine-cycle. If the
sample is high in one cycle and low in the next, then a high to low transition is detected and the interrupts request flag IE0 or IE1 will be set. Since the external interrupts are sampled every machine-cycle, they have to
be held high or low for at least one complete machine-cycle. The IE0 and IE1 are automatically cleared when
the interrupt service routine is called. If the level triggered mode is selected, then the requesting source has to
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
hold the pin low till the interrupt is serviced. The IE0 and IE1 will not be cleared by the hardware on entering
the service routine. In the level triggered mode, IE0 and IE1 follows the inverse value of INT0 and INT1 pins.
If interrupt pins continue to be held low even after the service routine is completed, the processor will
acknowledge another interrupt request from the same source. N78E517A (on PLCC-44, PQFP-44, TQFP-44,
and LQFP-48 packages) possessed other two external interrupts INT2 and INT3 . Their setting and operation
are just the same as interrupt 0 and 1. All configuring bits locate in XICON. The individual interrupt flag corresponding to external interrupt 2 to 3 will also be automatically cleared via hardware once its own interrupt service routine is executed.
The Timer 0 and 1 Interrupts are generated by the TF0 and TF1 flags. These flags are set by the overflow in
the Timer 0 and Timer 1 and automatically cleared by the hardware when the timer interrupt is serviced. TF2 or
EXF2 flag generates the Timer 2 interrupt. These flags are set by overflow, capture, or reload events in the
Timer 2 operation. The hardware will not clear these flags when a Timer 2 interrupt service routine executes.
Software has to resolve the cause of the interrupt between TF2 and EXF2 and clear the appropriate flag.
The serial port can generate interrupts on reception or transmission. There are two interrupt sources from the
serial port block, which are obtained by the RI and TI bits in the SCON. These bits are not automatically
cleared by the hardware. The user has to clear these bits via software.
The Power Down waking-up timer can be used as a simple timer. The Power Down waking-up timer interrupt
flag PDTF (PDCON.5) is set once an overflow occurs. If the interrupt is enabled by the enable bit EPDT
(EIE.1), then an interrupt will occur.
Brown-out detection, if enabled, can cause Brown-out flag BOF (PMC.3) to be asserted if power voltage drop
below Brown-out voltage level. The interrupt will occur if BORST (PMC.4) is 0 and EBOD (EIE.2) is 1.
SPI asserts interrupt flag SPIF (SPSR.7) on completion of data transfer with an external device. If SPI interrupt
enable bit ESPI (EIE.0), a serial peripheral interrupt generates. SPIF flag is software clear. MODF (SPSR.4)
and SPIOVF (SPSR.5) will also generate SPI interrupt. They share the same vector address with SPIF. When
interrupt is generated, the user should tell which flag requires the interrupt.
All the bits that generate interrupts can be set or reset via hardware, and thereby software initiated interrupts
can be generated. Each of the individual interrupts can be enabled or disabled by setting or clearing its controlling bit in the IE or EIE. IE also has a global enable bit EA (IE.7) which can be cleared to disable all the interrupts at once. It is set to enable all individually enabled interrupt.
Note that every interrupts, if enabled, is generated by a setting as a logic 1 of its interrupt flag no matter by
hardware or software. The user should take care of each interrupt flag in its own interrupt service routine (ISR).
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Most of interrupt flags must be cleared by writing it as a logic 0 via software. Without clearing the flag, the ISR
of corresponding interrupt source will execute again and again non-stopped.
17.1 Priority Level Structure
There are four priority levels for the interrupts, highest, high, low, and lowest. The interrupt sources can be individually set to one of four priority levels by setting their own priority bits. Table 17–2 lists four priority setting.
Naturally, a low priority interrupt can itself be interrupted by a high priority interrupt, but not by another same
level interrupt or lower level. A highest priority cannot be interrupted by any other interrupt source. In addition,
there exists a pre-defined hierarchy among the interrupts themselves. This hierarchy comes into play when the
interrupt controller has to resolve simultaneous requests having the same priority level. This hierarchy is defined as shown on Table 17–3. It also summarizes the interrupt sources, flag bits, vector addresses, enable
bits, priority bits, natural priority and the permission to wake up the CPU from Power Down mode. For details of
waking CPU up from Power Down mode, please see Section 19.2 “Power Down Mode” on page 101.
Table 17–2. Interrupt Priority Level Setting
Interrupt Priority Control Bits
Interrupt Priority Level
IPH / EIPH
IP / EIP / XICON[7,3]
0
0
Level 0 (lowest)
0
1
Level 1
1
0
Level 2
1
1
Level 3 (highest)
Table 17–3. Characteristics of Each Interrupt Source
Source
Vector
Address
Flag
[1]
External interrupt 0
0003H
IE0
Timer 0 overflow
000BH
TF0
[2]
[1]
External interrupt 1
0013H
IE1
Timer 1 overflow
001BH
TF1
Serial port (UART)
0023H
RI + TI
[2]
[2]
Enable Bit
Natural
Power Down
Priority Control Bits
Priority
Waking up
EX0
1
PX0, PX0H
Yes
ET0
2
PT0, PT0H
No
EX1
3
PX1, PX1H
Yes
ET1
4
PT1, PT1H
No
ES
5
PS, PSH
No
ET2
6
PT2, PT2H
No
Timer 2 overflow / capture / reload
002BH
TF2
External interrupt 2
0033H
IE2
[1]
EX2
7
PX2, PX2H
Yes
External interrupt 3
003BH
IE3
[1]
EX3
8
PX3, PX3H
Yes
+ EXF2
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Source
SPI interrupt
Vector
Address
0043H
Flag
Enable Bit
Natural
Power Down
Priority Control Bits
Priority
Waking up
SPIF (SPSR.7) +
MODF (SPSR.4) +
SPIOVF (SPSR.5)
ESPI
(EIE.0)
9
PSPI (EIP.0),
PSPIH (EIPH.0)
No
Power Down waking-up 004BH
timer interrupt
PDTF (PDCON.5)
EPDT
(EIE.1)
10
PPDT (EIP.1),
PPDTH (EIPH.1)
Yes
Brown-out interrupt
BOF (PMC.3)
EBOD
(EIE.2)
11
PBOD (EIP.2),
PBODH (EIPH.2)
Yes
0053H
[1] While the external interrupt pin is set as edge triggered (ITx = 1), its own flag Iex will be automatically cleared if the interrupt service routine (ISR) is executed. While as level triggered (Itx = 0), Iex follows the inverse of respective pin state.
It is not controlled via software.
[2] TF0 and TF1 will be automatically cleared if the interrupt service routine (ISR) is executed. But be aware that TF2 will
not.
The interrupt flags are sampled every machine-cycle. In the same machine-cycle, the sampled interrupts are
polled and their priority is resolved. If certain conditions are met then the hardware will execute an internally
generated LCALL instruction which will vector the process to the appropriate interrupt vector address. The
conditions for generating the LCALL are,
1. An interrupt of equal or higher priority is not currently being serviced.
2. The current polling cycle is the last machine-cycle of the instruction currently being executed.
3. The current instruction does not involve a write to any enable or priority setting bits and is not a RETI.
If any of these conditions are not met, then the LCALL will not be generated. The polling cycle is repeated every machine-cycle. If an interrupt flag is active in one cycle but not responded to for the above conditions are not
met, if the flag is not still active when the blocking condition is removed, the denied interrupt will not be serviced. This means that the interrupt flag, which was once active but not serviced, is not remembered. Every
polling cycle is new.
The processor responds to a valid interrupt by executing an LCALL instruction to the appropriate service routine. This action may or may not clear the flag, which caused the interrupt according to different interrupt
source. The hardware LCALL behaves exactly like the software LCALL instruction. This instruction saves the
Program Counter contents onto the Stack RAM but does not save the Program Status Word (PSW). The PC is
reloaded with the vector address of that interrupt which caused the LCALL. Execution continues from the vectored address till an RETI instruction is executed. On execution of the RETI instruction the processor pops the
Stack and loads the PC with the contents at the top of the stack. The user must take care that the status of the
stack is restored to what it was after the hardware LCALL. If the execution is to return to the interrupted program, the processor does not notice anything if the stack contents are modified and will proceed with execution
from the address put back into PC. Note that a simple RET instruction would perform exactly the same process
as a RETI instruction, but it would not inform the Interrupt controller that the interrupt service routine is com- 90 -
pleted. RET would leave the controller still thinking that the service routine is underway, making future interrupts impossible.
17.2 Interrupt Latency
The response time for each interrupt source depends on several factors, such as the nature of the interrupt
and the instruction underway. In the case of external interrupts INT0 and INT1 , they are sampled at every
machine-cycle and then their corresponding interrupt flags IE0 or IE1 will be set or reset. The value are not
actually polled by the circuit until the next machine-cycle. If a request is active and all three previous conditions
are met, then the hardware generated LCALL is executed. This LCALL itself takes 2 machine-cycles to be
completed. Thus there is a minimum time of 3 machine-cycles between the interrupt flag being set and the interrupt service routine being executed.
A longer response time should be anticipated if any of the three conditions are not met. If a higher or equal priority is being serviced, then the interrupt latency time obviously depends on the nature of the service routine
currently being executed. If the polling cycle is not the last machine-cycle of the instruction being executed,
then an additional delay is introduced. The maximum response time (if no other interrupt is in service) occurs if
the device is performing a write to IE, IP and then executes a MUL or DIV instruction. From the time an interrupt source is activated, the longest reaction time is 9 machine-cycles. This time includes 1 machine-cycle to
detect the interrupt, 2 machine-cycles to complete the IE, EIE, IP, IPH, EIP, or EIPH access, 4 machine-cycles
to complete the MUL or DIV instruction and 2 machine-cycles to complete the hardware LCALL to the interrupt
vector location.
Thus in a single-interrupt system the interrupt response time will always be more than 3 machine-cycles and
not more than 9 machine-cycles.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
18. IN SYSTEM PROGRAMMING (ISP)
The internal Program Memory and on-chip Data Flash support both hardware programming and in system programming (ISP). Hardware programming mode uses gang-writers to reduce programming costs and time to
market while the products enter into the mass production state. However, if the product is just under development or the end product needs firmware updating in the hand of an end user, the hardware programming mode
will make repeated programming difficult and inconvenient. ISP method makes it easy and possible.
N78E517A supports ISP mode allowing a device to be reprogrammed under software control. Furthermore, the
capability to update the application firmware makes wide range of applications possible.
ISP is performed without removing the microcontroller from the system. The most common method to perform
ISP is via UART along with the firmware in LDROM. General speaking, PC transfers the new APROM code
through serial port. Then LDROM firmware receives it and re-programs into APROM through ISP commands.
Nuvoton provides ISP firmware, USB ISP writer and PC application program for N78E517A. It makes users
quite easy perform ISP through Nuvoton standard ISP tool. Please explore Nuvoton 8-bit Microcontroller website: Nuvoton 80C51 Microcontroller Development Tool.
18.1 ISP Procedure
Unlike RAM‟s real-time operation, to update flash data often takes long time. Furthermore, it is a quite complex
timing procedure to erase, program, or read flash data. Fortunately, N78E517A carried out the flash operation
with convenient mechanism to help the user update the flash content. After ISP enabled by setting ISPEN
(CHPCON.0 with TA protected), the user can easily fill the 16-bit target address in ISPAH and ISPAL, data in
ISPFD and command in ISPCN. Then the ISP is ready to begin by setting a triggering bit ISPGO (ISPTRG.0).
Note that ISPTRG is also TA protected. At this moment, the CPU holds the Program Counter and the built-in
ISP automation takes over to control the internal charge-pump for high voltage and the detail signal timing. After ISP action completed, the Program Counter continues to run the following instructions. The ISPGO bit will
be automatically cleared. The user may repeat steps above for next ISP action if necessary. Through this progress, the user can easily erase, program, and verify the embedded flash by just taking care of the pure software.
The following registers relate to ISP processing.
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CHPCON – Chip Control (TA protected)
7
6
5
4
3
2
1
0
SWRST
ISPF
LDUEN
XRAMEN
BS
ISPEN
w
r/w
r/w
r/w
r/w
r/w
Address: 9FH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
6
ISPF
ISP fault flag.
The hardware will set this bit when any of the following condition is met:
1. The accessing area is illegal, such as,
(a) Erasing or programming APROM itself when APROM code runs.
(b) Erasing or programming LDROM when APROM code runs but LDUEN is 0.
I Erasing, programming, or reading CONFIG bytes when APROM code runs.
(d) Erasing or programming LDROM itself when LDROM code runs.
(e) Accessing oversize.
2. The ISP operating runs from internal Program Memory into external one.
This bit should be cleared via software.
5
LDUEN
Updating LDROM enable.
0 = The LDROM is inhibited to be erased or programmed when APROM code
runs. LDROM remains read-only.
1 = The LDROM is allowed to be fully accessed when APROM code runs.
0
ISPEN
ISP enable.
0 = Enable ISP function.
1 = Disable ISP function.
To enable ISP function will start the internal 22.1184MHz RC oscillator for timing
control. To clear ISPEN should always be the last instruction after ISP operation
in order to stop internal RC for reducing power consumption.
ISPCN – ISP Control
7
6
ISPA.17
ISPA.16
r/w
r/w
Address: AFH
Bit
Name
7:6
ISPA[17:16]
5
FOEN
4
FCEN
3:0
FCTRL[3:0]
5
FOEN
r/w
4
FCEN
r/w
3
FCTRL.3
r/w
2
FCTRL.2
r/w
1
0
FCTRL.1
FCTRL.0
r/w
r/w
reset value: 0000 0000b
Description
ISP control.
This byte is for ISP controlling command to decide ISP destinations and actions. For details, see Table 18–1. ISP Modes and Command Codes.
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Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
ISPAH – ISP Address High Byte
7
6
5
4
3
2
1
0
ISPA[15:8]
r/w
Address: A7H
reset value: 0000 0000b
Bit
Name
7:0
ISPA[15:8]
Description
ISP address high byte.
ISPAH contains address ISPA[15:8] for ISP operations.
ISPAL – ISP Address Low Byte
7
6
5
4
3
2
1
0
ISPA[7:0]
r/w
Address: A6H
reset value: 0000 0000b
Bit
Name
7:0
ISPA[7:0]
ISPFD – ISP Flash Data
7
6
Description
ISP address low byte.
ISPAL contains address ISPA[7:0] for ISP operations.
5
4
3
2
1
0
ISPFD[7:0]
r/w
Address: AEH
reset value: 0000 0000b
Bit
Name
7:0
ISPFD[7:0]
Description
ISP flash data.
This byte contains flash data which is read from or is going to be written to the
flash memory. The user should write data into ISPFD for program mode before
triggering ISP processing and read data from ISPFD for read/verify mode after
ISP processing is finished.
ISPTRG – ISP Trigger (TA protected)
7
6
5
Address: A4H
4
-
3
-
2
-
1
0
ISPGO
w
reset value: 0000 0000b
Bit
Name
Description
0
ISPGO
ISP go.
ISP begins by setting this bit as a logic 1. After this instruction, the CPU holds
the Program Counter (PC) and the ISP hardware automation takes over to control the progress. After ISP action completed, the Program Counter continues to
run the following instructions. The ISPGO bit will be automatically cleared and
always read as logic 0.
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18.2 ISP Commands
N78E517A provides a wide application to perform ISP to APROM, LDROM or on-chip Data Flash. The ISP
action mode and the destination of the flash block are defined by ISP control register ISPCN.
Table 18–1. ISP Modes and Command Codes
ISPCN
FCTRL[3:0]
ISPAH, ISPAL
ISPA[15:0]
ISPFD[7:0]
FCEN
1
X
X
X
ISP Mode
ISPA.17, ISPA.16 FOEN
Standby
[1]
X, X
1
APROM and Data Flash
Page Erase
0, 0
1
0
0010
Address in
[2]
LDROM Page Erase
0, 1
1
0
0010
Address in
[2]
APROM and Data Flash
Program
0, 0
1
0
0001
Address in
Data in
LDROM Program
0, 1
1
0
0001
Address in
Data in
APROM and Data Flash
Read
0, 0
0
0
0000
Address in
Data out
LDROM Read
0, 1
0
0
0000
Address in
Data out
All CONFIG bytes Erase
1, 1
1
0
0010
00XXH
X
CONFIG Program
1, 1
1
0
0001
CONFIG0: 0000H
CONFIG1: 0001H
CONFIG2: 0002H
CONFIG3: 0003H
Data in
CONFIG Read
1, 1
0
0
0000
CONFIG0: 0000H
CONFIG1: 0001H
CONFIG2: 0002H
CONFIG3: 0003H
Data out
X
X
[1] “x” means “don‟t care”.
[2] Each page is 256-byte size. Therefore, the address for Page Erase should be 0000H, 0100H, 0200H, 0300H, etc.,
which is incremented by one of high byte address.
18.3 User Guide of ISP
ISP facilitates the updating flash contents in a convenient way; however, the user should follow some restricted
laws in order that the ISP operates correctly. Without noticing warnings will possible cause undetermined results even serious damages of devices. Be attention of these notices. Furthermore, this paragraph will also
support useful suggestions during ISP procedures.
(1) If no more ISP operation needs, the user must clear ISPEN (CHPCON.0) to zero. It will make the system
void to trigger ISP unaware. Furthermore, ISP requires internal 22.1184MHZ RC oscillator running. If the external clock source is chosen, disabling ISP will stop internal 22.1184MHz RC for saving power consumption.
Note that a write to ISPEN is TA protected.
- 95 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
(2) If the loader code, which controls the ISP procedure, locates in the external Program Memory or runs from
the internal into the external, the ISP will not work anymore and set error indicator ISPF for data security.
(3) CONFIG bytes can be ISP fully accessed only when loader code executing in LDROM. New CONFIG bytes
other than CBS bit activate after all resets. New CBS bit activates after resets other than software reset.
(4) When the LOCK bit (CONFIG0.1) is activated, ISP reading, writing, or erasing can still be valid.
(5) ISP erasing or programming works from VDD 3.0V through 5.5V.
(6) APROM and LDROM can read itself through ISP method.
During ISP progress, interrupts (if enabled) should be disabled temporally by clearing EA bit for implement limitation.
Note that If the user would like to develop your own ISP program, remember always erase and program
CONFIG bytes at the last step for data security.
18.4 ISP Demo Code
;******************************************************************************
;
This code illustrates how to do APROM and CONFIG ISP from LDROM.
;
APROM are re-programmed by the code to output P1 as 55h and P2 as aah.
;
The CONFIG3 is also updated to 6T mode.
;
The user should put this code in LDROM and boot from LDROM.
;******************************************************************************
PAGE_ERASE_AP
EQU
00100010b
BYTE_PROGRAM_AP
EQU
00100001b
BYTE_READ_AP
EQU
00000000b
BYTE_READ_CONFIG
EQU
11000000b
BYTE_PROGRAM_CONFIG
EQU
11100001b
ALL_ERASE_CONFIG
EQU
11100010b
ORG
0000h
CALL
CLR
CALL
CALL
CALL
CALL
CALL
CALL
CALL
CALL
CALL
MOV
MOV
ANL
MOV
MOV
ORL
Enable_ISP
EA
Erase_AP
Erase_AP_Verify
Program_AP
Program_AP_Verify
Read_Config
Erase_Config
Program_Config
Program_Config_Verify
Disable_ISP
TA,#0Aah
TA,#55h
CHPCON,#0FDh
TA,#0Aah
TA,#55h
CHPCON,#80h
;disable all interrupts
;erase AP data
;verify Erase AP data
;programming AP data
;verify Programmed AP data
;read back CONFIG3
;erase CONFIG bytes
;programming CONFIG3 with new data
;verify Programmed CONFIG3
;TA protection
;
;BS = 0, reset to APROM
;software reset and reboot from APROM
- 96 -
SJMP
$
;********************************************************************
;
ISP Function
;********************************************************************
Enable_ISP:
MOV
TA,#0Aah
;CHPCON is TA protected
MOV
TA,#55h
ORL
CHPCON,#00000001b
;ISPEN = 1, enable ISP mode
RET
Disable_ISP:
MOV
TA,#0Aah
;CHPCON is TA protected
MOV
TA,#55h
ANL
CHPCON,#11111110b
;ISPEN = 0, disable ISP mode
RET
Trigger_ISP:
MOV
TA,#0Aah
MOV
TA,#55h
ORL
ISPTRG,#00000001b
;write „1‟ to ISPGO to trigger ISP process
RET
;********************************************************************
;
ISP AP Function
;********************************************************************
Erase_AP:
MOV
ISPCN,#PAGE_ERASE_AP
MOV
ISPAL,#00h
MOV
R0,#00h
Erase_AP_Loop:
MOV
ISPAH,R0
CALL
Trigger_ISP
INC
R0
CJNE
R0,#0,Erase_AP_Loop
RET
Erase_AP_Verify:
MOV
ISPCN,#BYTE_READ_AP
MOV
ISPAH,#00h
MOV
ISPAL,#00h
Erase_AP_Verify_Loop:
MOV
ISPFD,#00h
;clear ISPFD Data
CALL
Trigger_ISP
MOV
A,ISPFD
CJNE
A,#0FFh,Erase_AP_Verify_Error
INC
ISPAL
MOV
A,ISPAL
CJNE
A,#0,Erase_AP_Verify_Loop
INC
ISPAH
MOV
A,ISPAH
CJNE
A,#0,Erase_AP_Verify_Loop
RET
Erase_AP_Verify_Error:
CALL
Disable_ISP
mov
P0,#00h
SJMP
$
Program_AP:
MOV
ISPCN,#BYTE_PROGRAM_AP
MOV
ISPAH,#00h
MOV
ISPAL,#00h
MOV
DPTR,#AP_code
Program_AP_Loop:
MOV
A,#0
- 97 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
MOVC
A,@A+DPTR
MOV
ISPFD,A
CALL
Trigger_ISP
INC
DPTR
INC
ISPAL
MOV
A,ISPAL
CJNE
A,#8,Program_AP_Loop
RET
Program_AP_Verify:
MOV
ISPCN,#BYTE_READ_AP
MOV
ISPAH,#00h
MOV
ISPAL,#00h
MOV
DPTR,#AP_code
Program_AP_Verify_Loop:
MOV
ISPFD,#00h
;clear ISPFD Data
CALL
Trigger_ISP
MOV
A,#0
MOVC
A,@A+DPTR
MOV
B,A
MOV
A,ISPFD
CJNE
A,B,Program_AP_Verify_Error
INC
DPTR
INC
ISPAL
MOV
A,ISPAL
CJNE
A,#8,Program_AP_Verify_Loop
RET
Program_AP_Verify_Error:
CALL
Disable_ISP
mov
P0,#00h
SJMP
$
;********************************************************************
;
ISP Config Function
;********************************************************************
Erase_Config:
MOV
ISPCN,#ALL_ERASE_CONFIG
MOV
ISPAH,#00h
CALL
Trigger_ISP
RET
Read_Config:
MOV
ISPCN,#BYTE_READ_CONFIG
MOV
ISPAH,#00h
MOV
ISPAL,#03h
CALL
Trigger_ISP
MOV
A,ISPFD
RET
Program_Config:
MOV
ISPCN,#BYTE_PROGRAM_CONFIG
MOV
ISPAH,#00h
MOV
ISPAL,#03h
ANL
A,#10111111b
MOV
ISPFD,A
;switch to 6T mode
MOV
R0,A
;temp data
CALL
Trigger_ISP
RET
Program_Config_Verify:
MOV
ISPCN,#BYTE_READ_CONFIG
MOV
ISPAH,#00h
MOV
ISPAL,#03h
MOV
ISPFD,#00h
;clear ISPFD Data
CALL
Trigger_ISP
MOV
B,R0
MOV
A,ISPFD
- 98 -
CJNE
A,B,Program_CONFIG_Verify_Error
RET
Program_CONFIG_Verify_Error:
CALL
Disable_ISP
mov
P0,#00h
SJMP
$
;********************************************************************
;
APROM code
;********************************************************************
AP_code :
DB
75h, 90h, 55h
;OPCODEs of “mov
P1,#55h”
DB
75h,0A0h,0Aah
;OPCODEs of “mov
P2,#0aah”
DB
80h,0Feh
;OPCODEs of “sjmp
$”
END
- 99 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
19. POWER SAVING MODES
N78E517A has several features that help the user to control the power consumption of the device. The power
saved features have the Power Down mode and the Idle mode of operation. For a stable current consumption,
states of P0 pins should be taken care of. P0 should be set as 0 if floating or external pull-downs exist. Or P0
should be set as 1 if external pull-ups exist or internal pull-ups are enabled by P0UP (P0OR.0).
In system power saving modes, the Watchdog Timer should be specially taken care. The hardware will clear
WDT counter automatically after entering into or being woken-up from Idle or Power Down mode. It prevents
unconscious system reset.
PCON – Power Control
7
6
SMOD
r/w
Address: 87H
5
-
4
3
2
1
0
POF
GF1
GF0
PD
IDL
r/w
r/w
r/w
r/w
r/w
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
1
PD
Power Down mode.
Setting this bit puts MCU into Power Down mode. Under this mode, both CPU and
peripheral clocks stop and Program Counter (PC) suspends. It provides the lowest
power consumption. After CPU is woken up from Power Down, this bit will be automatically cleared via hardware and the program continue executing the interrupt
service routine (ISR) of the very interrupt source that woke the system up before.
After return from the ISR, the device continues execution at the instruction which
follows the instruction that put the system into Power Down mode.
Note that If IDL bit and PD bit are set simultaneously, the MCU will enter into
Power Down mode. Then it does not go to Idle mode after exiting Power Down.
0
IDL
Idle mode.
Setting this bit puts MCU into Idle mode. Under this mode, the CPU clock stops
and Program Counter (PC) suspends. After CPU is woken up from Idle, this bit
will be automatically cleared via hardware and the program continue executing the
ISR of the very interrupt source that woke the system up before. After return from
the ISR, the device continues execution at the instruction which follows the instruction that put the system into Idle mode.
19.1 Idle Mode
Idle mode suspends CPU processing by holding the Program Counter. No program code are fetched and run
in Idle mode. It forces the CPU state to be frozen. The Program Counter (PC), the Stack Pointer (SP), the Program Status Word (PSW), the Accumulator (ACC), and the other registers hold their contents during Idle mode.
The port pins hold the logical states they had at the time Idle was activated. Generally, it saves considerable
power of typical half of the full operating power.
- 100 -
Since the clock provided for peripheral function logic circuit like timer or serial port still remain in Idle mode, the
CPU can be released from the Idle mode using any of the interrupt sources if enabled. The user can put the
device into Idle mode by writing 1 to the bit IDL (PCON.0). The instruction that sets the IDL bit is the last instruction that will be executed before the device goes into Idle mode.
The Idle mode can be terminated in two ways. First, any interrupt if enabled will cause an exit. It will automatically clear the IDL bit, terminate the Idle mode, and the interrupt service routine (ISR) will be executed. After
using the RETI instruction to jump out of the ISR, execution of the program will be the one following the instruction which put the CPU into Idle mode. The second way to terminate the Idle mode is with any reset other than
software reset. Remember that if Watchdog reset is used to exit Idle mode, the WIDPD (WDCON.4) needs to
be set 1 to let Watchdog Timer keep running in Idle mode.
19.2 Power Down Mode
Power Down mode is the lowest power state that N78E517A can enter. It remain the power consumption as
a ”μA” level by stopping the system clock no matter internal RC clock or external crystal. Both of CPU and peripheral functions like Timers or UART are frozen. Flash memory stops. All activity is completely stopped and
the power consumption is reduced to the lowest possible value. The device can be put into Power Down mode
by writing 1 to bit PD (PCON.1). The instruction that does this action will be the last instruction to be executed
before the device goes into Power Down mode. In the Power Down mode, RAM maintains its content. The port
pins output the values held by their respective.
There are two ways to exit N78E517A from the Power Down mode. First is with all resets except software reset. Brown-out reset will also wake up CPU from Power Down mode. Be sure that Brown-out detection is enabled before the system enters into Power Down. But for a principle of least power consumption, it is uncommon
to enable Brown-out detection in Power Down mode. It is not a recommended application. Of course the RST
pin reset and power-on reset will remove the Power Down status. After RST pin reset or power-on reset. The
CPU is initialized and start executing program code from the beginning.
N78E517A can be woken up from the Power Down mode by forcing an external interrupt pin activated, providing the corresponding interrupt enabled and the global enable EA bit (IE.7) is set. If these conditions are met,
then the trigger on the external pin will asynchronously restart the system clock. Then device executes the interrupt service routine (ISR) for the corresponding external interrupt. After the ISR is completed, the program
execution returns to the instruction after the one which put the device into Power Down mode and continues.
The Power Down waking-up timer interrupt is also allowed to wake up Power Down. It is usually applied as a
long period timer to monitoring a static behavior. For detail application, please see Section 12.2 “Applications
of Power Down Waking-up Timer” on page 51. Brown-out interrupt is another source to wake up CPU from
- 101 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Power Down. As mentioned before the user will endure the large current of Brown-out detection circuit. It is not
a typical application.
- 102 -
20. CLOCK SYSTEM
N78E517A provides three options of the system clock source. It is configured by FOSC (CONFIG3.1),which
switches the system clock from crystal/resonator/external clock from XTAL1 pin or on-chip RC oscillator.
N78E517A embeds an on-chip RC oscillator of 22.1184MHz/11.0592MHz selected by CONFIG setting, factory
trimmed to ± 1% at room temperature. If the external clock source is from the crystal, the frequency supports
from 4MHz to 40MHz.
Flash
XTAL1
Oscillating
Circuit
External
Crystal
1
FIHRC
XTAL2
Internal RC
Oscillator
(22.1184MHz)
1
1/2
1: turn on
0: turn off
FOSC
0
0
1/2
0
INOSCFS
(CONFIG3.3)
1: 12T mode
0: 6T mode
FPRIPH
EN6T
(CONFIG3.6)
CFOSC
(CONFIG3.1)
ISPEN
(CHPCON.0)
ISP
Internal RC
Oscillator
(~10kHz)
FCPU
1
80C51
CPU
Timers
Serial Port
(UART)
SPI
PWM
FILRC
Watchdog
Timer
LPBOD
(PMC.2)
Power Down
Waking-up
Timer
Brown-out
Detection
Figure 20–1. Clock System Block Diagram
20.1 12T/6T mode
The clock for the entire circuit and peripherals is normally divided by 2 before being used by the CPU core and
peripherals. In 6T mode, this divider is bypassed. This facility provides the same performance when operating
with a 24MHz oscillator in 12T mode as with a 12MHz oscillator in 6T mode, for example. The user may
choose a divided-by-2 frequency oscillator in 6T mode to reach the same performance as in the original 12T
mode. Therefore, it reduces EMI and power consumption if 6T mode is used.
- 103 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
CONFIG3
7
CWDTEN
r/w
6
EN6T
r/w
5
ROG
r/w
4
CKF
r/w
3
INTOSCFS
r/w
2
1
0
FOSC
r/w
unprogrammed value: 1111 1111b
Bit
Name
Description
6
EN6T
Enable 6T mode.
This bit switches MCU between 12T and 6T mode. See Figure 20–1. Clock
System Block Diagram for definitions in details.
1 = MCU runs at 12T mode. Each machine-cycle is equal to 12 clocks of system
oscillator. The operating mode is the same as a standard 8051 MCU. (FCPU
and FPERIPH is a half of FOSC.)
0 = MCU runs at 6T mode. Each machine-cycle is equal to 6 clocks of system
oscillator. This mode doubles the whole chip operation compared with the
standard 8051. (FCPU and FPERIPH is equal to FOSC.)
5
ROG
Reducing oscillator gain.
1 = Use normal gain for crystal oscillating. The crystal frequency can be up to
40MHz.
0 = Use reduced gain for crystal oscillating. The crystal frequency should be
lower than 24MHz. In reduced gain mode, it will also help to decrease EMI.
4
CKF
Clock filter enable.
1 = Enable clock filter. It increases noise immunity and EMC capacity.
0 = Disable clock filter.
3
INTOSCFS
2
-
1
FOSC
0
-
Internal RC oscillator frequency select.
1 = Select 22.1184MHz as the system clock if internal RC oscillator mode is
used. It bypasses the divided-by-2 path of internal oscillator to select
22.1184MHz output as the system clock source.
0 = Select 11.0592MHz as the system clock if internal RC oscillator mode is
used. The internal RC divided-by-2 path is selected. The internal oscillator is
equivalent to 11.0592MHz output used as the system clock.
Reserved.
Oscillator selection bit.
This bit selects the source of the system clock.
1 = Crystal, resonator, or external clock input.
0 = Internal RC oscillator.
Reserved.
CHPCON – Chip Control (TA protected)
7
6
5
4
3
2
1
0
SWRST
ISPF
LDUEN
XRAMEN
BS
ISPEN
w
r/w
r/w
r/w
r/w
r/w
Address: 9FH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
0
ISPEN
Description
ISP enable.
0 = Enable ISP function.
1 = Disable ISP function.
To enable ISP function will start the internal 22.1184MHz RC oscillator for timing
control. To clear ISPEN should always be the last instruction after ISP operation
in order to stop internal RC for reducing power consumption.
- 104 -
PMC – Power Monitoring Control (TA protected)
7
6
5
4
3
2
1
0
BODEN
BORST
BOF
LPBOD
BOS
r/w
r/w
r/w
r/w
r
Address: ACH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
3
LPBOD
Low power Brown-out detection enable.
This bit switches the Brown-out detection into a power saving mode. This bit is
only effective while BODEN = 1.
0 = Disable Brown-out power saving mode. Brown-out detection operates in normal mode if enabled. The detection is always on.
1 = Enable Brown-out power saving mode. Brown-out detection operates in power
saving mode if enabled. Enable this bit will switch on internal 10kHz RC to be
a timer for about 12.8ms interval of detection. The discrete detection will save
much power but the hysteresis feature disappears.
20.2 External Clock Source
The system clock source can be from external XTAL1 pin. When XTAL1 pin is driven by an external clock
source, XTAL2 should be left floating. XTAL1 and XTAL2 are the input and output, respectively, of an internal
inverting amplifier. A crystal or resonator can be used by connecting between XTAL1 and XTAL2 pins. The
crystal or resonator frequency from 4MHz up to 40MHz is allowed. While an external crystal or resonator is
used, ROG (CONFIG3.5) is for half gain selection of the inverting amplifier. When the system clock is lower
than 24MHz and ROG is configured as a 0, the system EMI can be reduced. CKF (CONFIG3.4) is the control
bit of clock filter circuit of XTAL1 input pin.
20.3 On-chip RC Oscillator
The on-chip RC oscillator is enabled while FOSC (CONFIG3.1) is 0. Setting INTOSCFS (CONFIG3.3) logic 0
will switch to a divided-by-2 path. Note that a 0.1μF capacitor is recommended to be added on XTAL1 pin to
gain the more precise frequency of the internal RC oscillator frequency if it is selected as the system clock
source.
- 105 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
21. POWER MONITORING
In order to prevent incorrect execution during power up and power drop, N78E517A provides three power monitor functions, power-on detection, Brown-out detection, and low power detection.
21.1 Power-on Detection
The power-on detection function is designed for detecting power up after power voltage reaches to a level
about 2.0V where the system can work. After power-on detected, the POF (PCON.4) will be set 1 to indicate a
cold reset, a power-on reset complete. The POF flag can be cleared via software.
21.2 Brown-out Detection
The other power monitoring function, Brown-out detection circuit is for monitoring the VDD level during execution. There are four programmable Brown-out trigger levels available for wide voltage applications. The four
nominal levels are 2.2V, 2.7V, 3.8V, and 4.5V selected via setting CBOV[1:0] in CONFIG2. When VDD drops to
the selected Brown-out trigger level (VBOD), the Brown-out detection logic will either reset the CPU or request a
Brown-out interrupt. The user may determine Brown-out reset or interrupt enable according to different application systems.
The Brown-out detection will request the interrupt while VDD drops below VBOD while BORST (PMC.4) is 0. In
this case, BOF (PMC.3) will set as a 1. After the user cleared this flag whereas VDD remains below VBOD, BOF
will not set again. BOF just acknowledge the user a power drop occurs. The BOF will set 1 after V DD goes
higher than VBOD to indicate a power resuming. The Brown-out circuit provides an useful status indicator BOS
(PMC.0), which is helpful to tell a Brown-out event or power resuming event occurrence. If BORST bit is set,
this will enable Brown-out reset function. After a Brown-out reset, BORF (RSR.2) will set 1 via hardware. It will
not be altered by reset other than power-on. Software can clear this bit. VBOD has a hysteresis of 20-200mV.
The Brown-out detection circuit also provides a low power Brown-out detection mode for power saving. When
LPBOD is set 1, the Brown-out detection repeatedly senses the power voltage about every 12.8ms. For the
interval counting, the internal 10kHz RC oscillator will turn on in Brown-out low power mode. Note that the hysteresis feature will disappear in low power Brown-out detection mode.
- 106 -
VDD
Brownout Detection
BOF
or
-
BOS
+
4 VBOD
Threshold
Voltage
Select
BORF
1: ON
0: OFF
Chip Reset
BORST
0
1
CBOV1
CBOV0
Brownout Interrupt
Always On
LPBOD
On/Off
Interval
Counter
Internal
10KHz RC
BODEN
Figure 21–1. Brown-out Detection Block Diagram
Power
VDD
VBODn
VPOR
Power-on
Power fail event
Brown-out event
VSS
[1]
POF
BOS[2]
BOF[2]
Reset
status
[1]
1 = reset state
0 = free running
TBOR
[3]
TBOR
------ brownout reset disabled
—— brownout reset enabled
[1] POF and BOF are both cleared by software.
[2] Brown-out reset is disabled. While the whole brown-out detection circuit disabled, BOS and BOF will keep 0.
[3] TBOR ~= 8ms
Figure 21–2. Power Monitoring Timing Diagram
- 107 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
CONFIG2
7
CBODEN
r/w
6
CBOV1
r/w
Bit
Name
7
CBODEN
6
CBOV1
5
CBOV0
4
CBORST
5
CBOV0
r/w
4
CBORST
r/w
3
-
2
1
0
unprogrammed value: 1111 1111b
Description
CONFIG Brown-out detect enable.
1 = Enable Brown-out detection.
0 = Disable Brown-out detection.
CONFIG Brown-out voltage select.
These two bits select one of four Brown-out voltage level.
CBOV1 CBOV0 Brown-out Voltage
1
1
2.2V
1
0
2.7V
0
1
3.8V
0
0
4.5V
CONFIG Brown-out reset enable.
This bit decides if a Brown-out reset is caused after a Brown-out event.
1 = Enable Brown-out reset when VDD drops below VBOD.
0 = Disable Brown-out reset when VDD drops below VBOD.
PMC – Power Monitoring Control (TA protected)
7
6
5
4
3
2
1
0
BODEN[1]
BORST[1]
BOF
LPBOD
BOS
r/w
r/w
r/w
r/w
r
Address: ACH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
Description
7
BODEN
6:5
-
4
BORST
3
BOF
Brown-out flag.
This flag will be set as a logic 1 via hardware after a VDD dropping below or rising
above VBOD event occurs. If both EBOD (EIE.2) and EA (IE.7) are set, a Brownout interrupt requirement will be generated. This bit must be cleared via software.
3
LPBOD
Low power Brown-out detection enable.
This bit switches the Brown-out detection into a power saving mode. This bit is
only effective while BODEN = 1.
0 = Disable Brown-out power saving mode. Brown-out detection operates in normal mode if enabled. The detection is always on.
1 = Enable Brown-out power saving mode. Brown-out detection operates in power
saving mode if enabled. Enable this bit will switch on internal 10kHz RC to be
a timer for about 12.8ms interval of detection. The discrete detection will save
much power but the hysteresis feature disappears.
Brown-out detect enable.
0 = Disable Brown-out detection.
1 = Enable Brown-out detection.
Reserved.
Brown-out reset enable.
This bit decides if a Brown-out reset is caused after a Brown-out event.
0 = Disable Brown-out reset when VDD drops below VBOD.
1 = Enable Brown-out reset when VDD drops below VBOD.
- 108 -
Bit
Name
1
-
Description
Reserved.
Brown-out status.
This bit indicates the VDD voltage level comparing with VBOD while Brown-out circuit is enabled. It is helpful to tell a Brown-out event or power resuming event occurrence. This bit is read-only and keeps 0 if Brown-out detection is not enabled.
0 = VDD voltage level is higher than VBOD.
1 = VDD voltage level is lower than VBOD.
[1] BODEN and BORST will be directly loaded from CONFIG2 bit 7 and bit 4 after all resets.
0
BOS
Table 21–1. BOF Reset Value
Reset source
CBODEN (CONFIG2.7)
CBORST (CONFIG2.4)
VDD stable level
BOF
Brown-out reset
1
1
> VBOD always
1
1
1
> VBOD always
1
1
0
> VBOD
1
1
0
< VBOD
0
0
X
X
0
Other resets
Note that if BOF is 1 after chip reset, it is strongly recommended to initialize the user’s program by
clearing BOF.
PCON – Power Control
7
6
SMOD
r/w
Address: 87H
Bit
Name
4
POF
5
-
4
3
2
1
0
POF
GF1
GF0
PD
IDL
r/w
r/w
r/w
r/w
r/w
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Description
Power-on reset flag.
This bit will be set as 1 after a power-on reset. It indicates a cold reset, a poweron reset complete. This bit remains its value after any other resets. This flag is
recommended to be cleared via software.
- 109 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
22. RESET CONDITIONS
N78E517A has several options to place device in reset condition. It also offers the software flags to indicate
the source, which causes a reset. In general, most SFRs go to their reset value irrespective of the reset condition, but there are several reset source indicating flags whose state depends on the source of reset. The user
can read back these flags to determine the cause of reset using software. There are 5 ways of putting the device into reset state. They are power-on reset, RST pin reset, software reset, Watchdog Timer reset, and
Brown-out reset.
RSR – Reset Status Register
7
6
Address: 96H
Bit
Name
7:3
-
2
BORF
1
-
0
SWRF
PCON – Power Control
7
6
SMOD
r/w
Address: 87H
Bit
Name
4
POF
5
-
4
3
2
1
0
BORF
SWRF
r/w
r/w
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Description
Reserved.
Brown-out reset flag.
When the MCU is reset by Brown-out reset, this bit will be set via hardware. This
flag is recommended to be cleared via software.
Reserved.
Software reset flag.
When the MCU is reset via software reset, this bit will be set via hardware. This
flag is recommended to be cleared via software.
5
-
4
3
2
1
0
POF
GF1
GF0
PD
IDL
r/w
r/w
r/w
r/w
r/w
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Description
Power-on reset flag.
This bit will be set as 1 after a power-on reset. It indicates a cold reset, a poweron reset complete. This bit remains its value after any other resets. This flag is
recommended to be cleared via software.
- 110 -
WDCON – Watchdog Timer Control (TA protected)
7
6
5
4
3
2
1
0
WDTEN
WDCLR
WIDPD
WDTRF
WPS2
WPS1
WPS0
r/w
w
r/w
r/w
r/w
r/w
r/w
Address: AAH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
3
WDTRF
Description
Watchdog Timer reset flag.
When the CPU is reset by Watchdog Timer time-out event, this bit will be set via
hardware. This flag is recommended to be cleared via software.
22.1 Power-on Reset
N78E517A incorporate an internal voltage reference. During a power-on process of rising power supply voltage
VDD, this voltage reference will hold the CPU in power-on reset mode when VDD is lower than the voltage reference threshold. This design makes CPU not access program flash while the VDD is not adequate performing
the flash reading. If a undetermined operating code is read from the program flash and executed, this will put
CPU and even the whole system in to a erroneous state. After a while, VDD rises above the reference threshold
where the system can work, the selected oscillator will start and then program code will be executed from
0000H. At the same time, a power-on flag POF (PCON.4) will be set 1 to indicate a cold reset, a power-on reset complete. Note that the contents of internal RAM will be undetermined after a power-on. The user is recommended to give initial values for the RAM block.
The POF is recommended to be cleared to 0 via software in order to check if a cold reset or warm reset performed after the next reset occurs. If a cold reset caused by power off and on, POF will be set 1 again. If the
reset is a warm reset caused by other reset sources, POF will remain 0. The user may take a different course
to check other reset flags and deal with the warm reset event.
22.2 Brown-out Reset
Brown-out detection circuit is for monitoring the VDD level during execution. When VDD drops to the selected
Brown-out trigger level (VBOD), the Brown-out detection logic will reset the CPU if BORST (PMC.4) setting 1.
After a Brown-out reset, BORF (RSR.2) will set 1 via hardware. It will not be altered by any reset other than a
power-on reset. Software can clear this bit.
22.3 RST Pin Reset
The hardware reset input is RST pin which is the input with a Schmitt trigger. A hardware reset is accomplished
by holding the RST pin high for at least two machine-cycles to ensure detection of a valid hardware reset sig-
- 111 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
nal. The reset circuitry then synchronously applies the internal reset signal. Thus the reset is a synchronous
operation and requires the clock to be running to cause an external reset.
Once the device is in reset condition, it will remain so as long as RST pin is 1. After the RST high is removed,
the CPU will exit the reset state and begin code executing from address 0000H. There is no flag associated
with the RST pin reset condition. However since the other reset sources have flags, the external reset can be
considered as the default reset if those reset flags are cleared.
If a RST pin reset applies while CPU is in Power Down mode, the way to trigger a hardware reset is slightly
different. Since the Power Down mode stops system clock, the reset signal will asynchronously cause the system clock resuming. After the system clock is stable, CPU will enter into the reset state.
22.4 Watchdog Timer Reset
The Watchdog Timer is a free running timer with programmable time-out intervals. The user can clear the
Watchdog Timer at any time, causing it to restart the count. When the selected time-out occurs, the Watchdog
Timer will reset the system directly. The reset condition is maintained via hardware for two machine-cycles.
After the reset is removed, the device will begin execution from 0000H.
Once a reset due to Watchdog Timer occurs the Watchdog Timer reset flag WDTRF (WDCON.3) will be set.
This bit keeps unchanged after any reset other than a power-on reset. The user may clear WDTRF via software.
22.5 Software Reset
N78E517A is enhanced with a software reset. It allows the program code to reset the whole system in software
approach. It is quite useful in the end of an ISP progress. For example, if an LDROM updating APROM ISP
finishes and the code in APROM is correctly updated, a software reset can be asserted to reboot CPU from the
APROM in order to check the result of the updated APROM program code immediately. Writing 1 to SWRST
(CHPCON.7) will trigger a software reset. Note that this bit is timed access protection. See demo code below.
After a software reset the SWRF (RSR.0) will be automatically set via hardware. This bit will be preserved its
value after all resets except power-on reset. SWRF can also be cleared via software.
- 112 -
CHPCON – Chip Control (TA protected)
7
6
5
4
3
2
1
0
SWRST
ISPF
LDUEN
XRAMEN
BS
ISPEN
w
r/w
r/w
r/w
r/w
r/w
Address: 9FH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
7
SWRST
Description
Software reset.
To set this bit as a logic 1 will cause a software reset. It will automatically be
cleared via hardware after reset in finished.
The software demo code are listed below.
MOV
MOV
ANL
MOV
MOV
ORL
TA,#0Aah
TA,#55h
CHPCON,#0FDh
TA,#0Aah
TA,#55h
CHPCON,#80h
;TA protection.
;
;BS = 0, reset to APROM.
;Software reset
22.6 Boot Select
CONFIG0.7
CHPCON.1
CBS
BS
Load
Power-on reset
Watchgod Timer reset
Reset and boot from APROM
BS = 0
Software reset
BS = 1
Reset and boot from LDROM
Brownout reset
RST-pin reset
Figure 22–1. Boot Selecting Diagram
N78E517A provides users a flexible boot selection for variant application. The SFR bit BS in CHPCON.1 determines CPU booting from APROM or LDROM after any source of reset. If reset occurs and BS is 0, CPU will
reboot from APPROM. Else, the CPU will reboot from LDROM.
- 113 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
CONFIG0
7
CBS
r/w
6
-
5
-
4
-
3
-
2
1
0
MOVCL
LOCK
DFEN
r/w
r/w
r/w
unprogrammed value: 1111 1111b
Bit
Name
Description
7
CBS
CONFIG boot select.
This bit defines from which block MCU boots after all resets except software reset.
1 = MCU will boot from APROM after all resets except software reset.
0 = MCU will boot from LDROM after all resets except software reset.
CHPCON – Chip Control (TA protected)
7
6
5
4
3
2
1
0
SWRST
ISPF
LDUEN
XRAMEN
BS[1]
ISPEN
w
r/w
r/w
r/w
r/w
r/w
Address: 9FH
reset value: see Table 6–2. N78E517A SFR Description and Reset Values
Bit
Name
1
BS
Description
Boot select.
There are different meanings of writing to or reading from this bit.
Writing:
It defines from which block MCU boots after all resets.
0 = The next rebooting will be from APROM.
1 = The next rebooting will be from LDROM.
Reading:
It indicates from which block MCU booted after previous reset.
0 = The previous rebooting is from APROM.
1 = The previous rebooting is from LDROM.
[1] Note that this bit is initialized by being loaded from the inverted value of CBS bit in CONFIG0.7 at all resets except software reset. It keeps unchanged after software reset.
Note that after the CPU is released from all reset state, the hardware will always check the BS bit instead of the CBS bit to determine from APROM or LDROM that the device reboots.
22.7 Reset State
The reset state does not affect the on-chip RAM. The data in the RAM will be preserved during the reset. Note
that the RAM contents may be lost if the VDD falls below approximately 1.2V. It is the minimum voltage level
required for RAM data retention. Therefore, after the power-on reset the RAM contents will be indeterminate.
During a power fail condition. If the power falls below the data retention minimum voltage, the RAM contents
will also lose.
After a reset, most of SFRs go to their initial values except bits which are affected by different reset events.
See the notes of Table 6–2. N78E517A SFR Description and Reset Values. The Program Counter is forced to
0000H and held as long as the reset condition is applied. Note that the Stack Pointer is also reset to 07H,
- 114 -
therefore the stack contents may be effectively lost during the reset event even though the RAM contents are
not altered.
After a reset, interrupts and Timers are disabled. The I/O port SFRs have FFH written into them which puts the
port pins in a high state.
- 115 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
23. AUXILIARY FEATURES
ALE is used to enable the address latch that separates the address from the data on Port 0. ALE runs at 1/6 of
the Fosc in 12T mode. An ALE pulse is omitted always. The user can turn ALE signal off via setting ALEOFF to
reduce EMI. ALEOFF enable will just make ALE activating during external memory access through a MOVC or
MOVX instruction. ALE will stay high in other conditions.
AUXR – Auxiliary Register
7
6
Address: 8EH
Bit
Name
7:1
-
0
ALEOFF
5
-
4
-
3
-
2
-
1
0
ALEOFF
r/w
reset value: 0000 0000b
Description
Reserved.
ALE output off.
0 = ALE is emitted always.
1 = ALE is off normally and active only during external memory access through a
MOVX or MOVC instruction.
- 116 -
24. CONFIG BYTES
N78E517A has several hardware configuration bytes, called CONFIG bytes, those are used to configure the
hardware options such as the security bits, system clock source, and so on. These hardware options can be
re-configured through the Programmer/Writer or ISP modes. N78E517A has four CONFIG bytes those are
CONFIG0-3. Several functions which are defined by certain CONFIG bits are also available to be re-configured
by certain SFR bits. Therefore, there is a need to load such CONFIG bits into respective SFR bits. Such loading will occurs after resets. (Software reset will reload all CONFIG bytes except CBS bit in CONFIG0.) These
SFR bits can be continuously controlled via user‟s software.
Note that CONFIG bits marked as “-“ should always keep unprogrammed.
CONFIG0
7
CBS
r/w
6
-
5
-
4
-
3
-
2
1
0
MOVCL
LOCK
DFEN
r/w
r/w
r/w
unprogrammed value: 1111 1111b
Bit
Name
Description
7
CBS
CONFIG boot select.
This bit defines from which block MCU boots after all resets except software reset.
1 = MCU will boot from APROM after all resets except software reset.
0 = MCU will boot from LDROM after all resets except software reset.
6:3
-
2
MOVCL
1
LOCK
Chip lock enable.
1 = Chip is unlocked. All of APROM, LDROM, and Data Flash are not locked.
Their contents can be read out through a parallel Programmer/Writer.
0 = Chip is locked. APROM, LDROM, and Data Flash are locked. Their contents
read through parallel Programmer/Writer will become FFH.
Note that CONFIG bytes are always unlocked and can be read. Hence, once the
chip is locked, the CONFIG bytes cannot be erased or programmed individually.
The only way to disable chip lock is to use the whole chip erase mode. However,
all data within APROM, LDROM, Data Flash, and other CONFIG bits will be
erased when this procedure is executed.
If the chip is locked, it does not alter the ISP function.
0
DFEN
Data Flash enable.
1 = There is no Data Flash space. The APROM size is 64k-byte.
0 = Data Flash exists. The Data Flash and APROM share 64k bytes depending on
SHBDA setting.
Reserved.
MOVC lock enable.
This bit determines MOVC instruction is inhibited or not when reading internal
Program Memory by executing on the external Program Memory. This mechanism
is for data security.
1 = MOVC has no restriction.
0 = MOVC is restricted. The external Program Memory code is inhibited to read
internal APROM or LDROM contents through MOVC instruction.
- 117 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
CONFIG0
7
6
5
4
3
2
1
0
CBS
-
-
-
-
MOVCL
LOCK
DFEN
7
6
5
4
3
2
1
0
SWRST
ISPF
LDUE
AUXRAM
-
-
BS
ISPEN
CHPCON
Figure 24–1. CONFIG0 Reset Reloading Except Software Reset
CONFIG1
7
6
5
4
3
[1]
CHBDA[7:0]
r/w
2
1
0
unprogrammed value: 1111 1111b
Bit
Name
Description
CONFIG high byte of Data Flash starting address.
This byte is valid only when DFEN (CONFIG0.0) being 0 condition. It is used to
determine the starting address of the Data Flash.
[1] Note that there will be no APROM if setting CHBDA 00H. CPU will execute codes in the external Program Memory.
7:0
CHBDA[7:0]
CONFIG1
7
6
5
4
3
2
1
0
2
1
0
CHBDA[7:0]
SHBDA
7
6
5
4
3
SHBDA[7:0]
Figure 24–2. CONFIG1 Reset Reloading
CONFIG2
7
CBODEN
r/w
6
CBOV1
r/w
5
CBOV0
r/w
4
CBORST
r/w
3
-
Bit
Name
Description
7
CBODEN
CONFIG Brown-out detect enable.
1 = Enable Brown-out detection.
0 = Disable Brown-out detection.
6
CBOV1
CONFIG Brown-out voltage select.
- 118 -
2
1
0
unprogrammed value: 1111 1111b
Bit
Name
Description
5
CBOV0
4
CBORST
3:0
-
These two bits select one of four Brown-out voltage level.
CBOV1 CBOV0 Brown-out Voltage
1
1
2.2V
1
0
2.7V
0
1
3.8V
0
0
4.5V
CONFIG Brown-out reset enable.
This bit decides if a Brown-out reset is caused after a Brown-out event.
1 = Enable Brown-out reset when VDD drops below VBOD.
0 = Disable Brown-out reset when VDD drops below VBOD.
Reserved.
CONFIG2
7
6
5
4
3
2
1
0
CBODEN
CBOV1
CBOV0
CBORST
-
-
-
-
7
6
5
4
3
2
1
0
BODEN
-
-
BORST
BOF
LPBOD
-
BOS
PMC
Figure 24–3. CONFIG2 Reset Reloading
CONFIG3
7
CWDTEN
r/w
6
EN6T
r/w
5
ROG
r/w
4
CKF
r/w
3
INTOSCFS
r/w
2
1
0
FOSC
r/w
unprogrammed value: 1111 1111b
Bit
Name
Description
7
CWDTEN
6
EN6T
Enable 6T mode.
This bit switches MCU between 12T and 6T mode. See Figure 20–1. Clock System
Block Diagram for definitions in details.
1 = MCU runs at 12T mode. Each machine-cycle is equal to 12 clocks of system
oscillator. The operating mode is the same as a standard 8051 MCU. (FCPU and
FPERIPH is a half of FOSC.)
0 = MCU runs at 6T mode. Each machine-cycle is equal to 6 clocks of system oscillator. This mode doubles the whole chip operation compared with the standard
8051. (FCPU and FPERIPH is equal to FOSC.)
5
ROG
Reducing oscillator gain.
1 = Use normal gain for crystal oscillating. The frequency can be up to 40MHz.
0 = Use reduced gain for crystal oscillating. The frequency should be lower than
24MHz. In reduced gain mode, it will also help to decrease EMI.
CONFIG Watchdog Timer enable.
1 = Disable Watchdog Timer after all resets.
0 = Enable Watchdog Timer after all resets.
- 119 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Bit
Name
Description
4
CKF
Clock filter enable.
1 = Enable clock filter. It increases noise immunity and EMC capacity.
0 = Disable clock filter.
Note that the clock filter should be always disabled if the crystal frequency is
above 24MHz.
3
INTOSCFS
Internal RC oscillator frequency select.
1 = Select 22.1184MHz as the system clock if internal RC oscillator mode is used.
It bypasses the divided-by-2 path of internal oscillator to select 22.1184MHz
output as the system clock source.
0 = Select 11.0592MHz as the system clock if internal RC oscillator mode is used.
The internal RC divided-by-2 path is selected. The internal oscillator is equivalent to 11.0592MHz output used as the system clock.
2
-
1
FOSC
0
CONFIG3
WDCON
Reserved.
Oscillator selection bit.
This bit selects the source of the system clock.
1 = Crystal, resonator, or external clock input.
0 = Internal RC oscillator.
Reserved.
7
6
5
4
3
2
1
0
CWDTEN
EN6T
ROG
CKF
INTOSCFS
-
FOSC
-
7
6
5
4
3
2
1
0
WDTEN
WDCLR
-
WIDPD
WDTRF
WPS2
WPS1
WPS0
Figure 24–4. CONFIG3 Reset Reloading
- 120 -
25. INSTRUCTION SET
N78E517A executes all the instructions of the standard 8051 family. All instructions are coded within an 8-bit
field called an OPCODE. This single byte must be fetched from Program Memory. The OPCODE is decoded
by the CPU. It determines what action the microcontroller will take and whether more operation data is needed
from memory. If no other data is needed, then only one byte was required. Thus the instruction is called a one
byte instruction. In some cases, more data is needed. These will be two or three byte instructions.
Table 25–1 lists all instructions in details. Note of the instruction set and addressing modes are shown below.
Rn (n = 0-7)
Register R0-R7 of the currently selected Register Bank.
direct
8-bit internal data location‟s address. It could be an internal data RAM location (0127) or a SFR (e.g., I/O port, control register, status register, etc. (128-255)).
@Ri (i = 0, 1)
8-bit internal data RAM location (0-255) addressed indirectly through register R0 or
R1.
#data
8-bit constant included in the instruction.
#data16
16-bit constant included in the instruction.
addr16
16-bit destination address. Used by LCALL and LJMP. A branch can be anywhere
within the 64k-byte Program Memory address space.
addr11
11-bit destination address. Used by ACALL and AJMP. The branch will be within the
same 2k-byte page of Program Memory as the first byte of the following instruction.
rel
Signed (2‟s complement) 8-bit offset byte. Used by SJMP and all conditional branches.
Range is -128 to +127 bytes relative to first byte of the following instruction.
bit
Direct addressed bit in internal data RAM or SFR.
Table 25–1. Instruction Set for N78E517A
Bytes
Clock Cycles
in 12T Mode
Clock Cycles
in 6T Mode
00
1
12
6
Instruction
NOP
OPCODE
ADD
A, Rn
28-2F
1
12
6
ADD
A, @Ri
26, 27
1
12
6
ADD
A, direct
25
2
12
6
ADD
A, #data
24
2
12
6
ADDC
A, Rn
38-3F
1
12
6
ADDC
A, @Ri
36, 37
1
12
6
ADDC
A, direct
35
2
12
6
ADDC
A, #data
34
2
12
6
SUBB
A, Rn
98-9F
1
12
6
SUBB
A, @Ri
96, 97
1
12
6
SUBB
A, direct
95
2
12
6
SUBB
A, #data
94
2
12
6
- 121 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Table 25–1. Instruction Set for N78E517A
Instruction
OPCODE
Bytes
Clock Cycles
in 12T Mode
Clock Cycles
in 6T Mode
INC
A
04
1
12
6
INC
Rn
08-0F
1
12
6
INC
@Ri
06, 07
1
12
6
INC
direct
05
2
12
6
INC
DPTR
A3
1
24
12
DEC
A
14
1
12
6
DEC
Rn
18-1F
1
12
6
DEC
@Ri
16, 17
1
12
6
DEC
direct
15
2
12
6
MUL
AB
A4
1
48
24
DIV
AB
84
1
48
24
DA
A
D4
1
12
6
ANL
A, Rn
58-5F
1
12
6
ANL
A, @Ri
56, 57
1
12
6
ANL
A, direct
55
2
12
6
ANL
A, #data
54
2
12
6
ANL
direct, A
52
2
12
6
ANL
direct, #data
53
3
24
12
ORL
A, Rn
48-4F
1
12
6
ORL
A, @Ri
46, 47
1
12
6
ORL
A, direct
45
2
12
6
ORL
A, #data
44
2
12
6
ORL
direct, A
42
2
12
6
ORL
direct, #data
43
3
24
12
XRL
A, Rn
68-6F
1
12
6
XRL
A, @Ri
66, 67
1
12
6
XRL
A, direct
65
2
12
6
XRL
A, #data
64
2
12
6
XRL
direct, A
62
2
12
6
XRL
direct, #data
63
3
24
12
CLR
A
E4
1
12
6
CPL
A
F4
1
12
6
RL
A
23
1
12
6
RLC
A
33
1
12
6
RR
A
03
1
12
6
RRC
A
13
1
12
6
SWAP
A
C4
1
12
6
MOV
A, Rn
E8-EF
1
12
6
MOV
A, @Ri
E6, E7
1
12
6
MOV
A, direct
E5
2
12
6
- 122 -
Table 25–1. Instruction Set for N78E517A
Instruction
OPCODE
Bytes
Clock Cycles
in 12T Mode
Clock Cycles
in 6T Mode
6
MOV
A, #data
74
2
12
MOV
Rn, A
F8-FF
1
12
6
MOV
Rn, direct
A8-AF
2
24
12
MOV
Rn, #data
78-7F
2
12
6
MOV
@Ri, A
F6, F7
1
12
6
MOV
@Ri, direct
A6, A7
2
24
12
MOV
@Ri, #data
76, 77
2
12
6
MOV
direct, A
F5
2
12
6
MOV
direct, Rn
88-8F
2
24
12
MOV
direct, @Ri
86, 87
2
24
12
MOV
direct, direct
85
3
24
12
MOV
direct, #data
75
3
24
12
MOV
DPTR, #data16
90
3
24
12
MOVC A, @A+DPTR
93
1
24
12
MOVC A, @A+PC
83
1
24
12
MOVX
A, @Ri
E2, E3
1
24
12
MOVX
A, @DPTR
E0
1
24
12
MOVX
@Ri, A
F2, F3
1
24
12
MOVX
@DPTR, A
F0
1
24
12
PUSH
direct
C0
2
24
12
POP
direct
D0
2
24
12
XCH
A, Rn
C8-CF
1
12
6
XCH
A, @Ri
C6, C7
1
12
6
XCH
A, direct
C5
2
12
6
XCHD
A, @Ri
D6, D7
1
12
6
CLR
C
C3
1
12
6
CLR
bit
C2
2
12
6
SETB
C
D3
1
12
6
SETB
bit
D2
2
12
6
CPL
C
B3
1
12
6
CPL
bit
B2
2
12
6
ANL
C, bit
82
2
24
12
ANL
C, /bit
B0
2
24
12
ORL
C, bit
72
2
24
12
ORL
C, /bit
A0
2
24
12
MOV
C, bit
A2
2
12
6
MOV
bit, C
92
2
24
12
ACALL addr11
11, 31, 51, 71, 91,
[1]
B1, D1, F1
2
24
12
LCALL addr16
12
3
24
12
- 123 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Table 25–1. Instruction Set for N78E517A
Bytes
Clock Cycles
in 12T Mode
Clock Cycles
in 6T Mode
22
1
24
12
Instruction
RET
RETI
OPCODE
32
1
24
12
AJMP
addr11
01, 21, 41, 61, 81,
[2]
A1, C1, E1
2
24
12
LJMP
addr16
02
3
24
12
JMP
@A+DPTR
73
1
24
12
SJMP
rel
80
2
24
12
JZ
rel
60
2
24
12
JNZ
rel
70
2
24
12
JC
rel
40
2
24
12
JNC
rel
50
2
24
12
JB
bit, rel
20
3
24
12
JNB
bit, rel
30
3
24
12
JBC
bit, rel
10
3
24
12
CJNE
A, direct, rel
B5
3
24
12
CJNE
A, #data, rel
B4
3
24
12
CJNE
@Ri, #data, rel
B6, B7
3
24
12
CJNE
Rn, #data, rel
B8-BF
3
24
12
DJNZ
Rn, rel
D8-DF
2
24
12
DJNZ direct, rel
D5
3
24
12
[1] The most three significant bits in the 11-bit address [A10:A8] decide the ACALL hex code. The code
will be [A10,A9,A8,1,0,0,0,1].
[2] The most three significant bits in the 11-bit address [A10:A8] decide the AJMP hex code. The code
will be [A10,A9,A8,0,0,0,0,1].
- 124 -
26. ELECTRICAL CHARACTERISTICS
26.1 Absolute Maximum Ratings
Parameter
Rating
Unit
Operating temperature under bias
-40 to +85
C
Storage temperature range
-55 to +150
C
Voltage on VDD pin to VSS
-0.3 to +6.5
V
-0.3 to (VDD+0.3)
V
Voltage on any other pin to VSS
Stresses at or above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. It is a stress rating only and functional operation of the device at these or any other conditions above
those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum
rating conditions may affect device reliability.
26.2 DC Electrical Characteristics
Temperature = -40℃ to +85℃; VSS = 0V;
VDD = 4.5V to 5.5V @ F = 0 to 40MHz (12T mode), F = 0 to 33MHz (6T mode)
VDD = 2.4V to 5.5V @ F = 0 to 27MHz (12T mode), F = 0 to 20MHz (6T mode)
VDD = 3.0V to 5.5V for ISP erasing or programming.
Table 26–1. DC Characteristics
Symbol
Parameter
VIL
Input low voltage
VIH
Input high voltage
Condition
Input high voltage
(RST, XTAL1)
VOL
Output low voltage
VOH
VOH1
Typ.
Max.
Unit
0.2VDD – 0.1 V
(Ports 0-4, EA )
VIH1
Min.
[1]
Output high voltage
(Ports 1-4 and Port 0 with
internal pull-up enabled)
0.2VDD + 0.9
V
0.7VDD
V
VDD = 4.5V, IOL = 8.2mA
VDD = 3.0V, IOL = 5.8mA
VDD = 2.4V, IOL = 4.4mA
0.4
V
VDD = 4.5V, IOH = -300μA
VDD = 3.0V, IOH = -75μA
VDD = 2.4V, IOH = -35μA
2.4
2.4
2.0
V
Output high voltage
VDD = 4.5V, IOH = -9mA
(Ports 0 and 2 in external bus VDD = 3.0V, IOH = -2.4mA
VDD = 2.4V, IOH = -1.3mA
mode, ALE, PSEN )
2.4
2.4
2.0
V
- 125 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Symbol
IIL
ITL
Parameter
Condition
Logical 0 input current
(Ports 1-4 and Port 0 with
internal pull-up enabled)
VDD = 5.5V, VIN = 0.4V
VDD = 3.6V, VIN = 0.4V
Logical 1-to-0 transition cur[2]
rent (Ports 1-4 and Port 0
with internal pull-up enabled)
VDD = 5.5V
VDD = 3.6V
Unit
-650
-290
μA
±10
μA
VDD = 5.0V, external clock, 12T
0.21F + 3.5
mA
VDD = 3.3V, external clock, 12T
0.15F + 2.9
mA
VDD = 5.0V, external clock, 6T
0.35F + 3.3
mA
VDD = 3.3V, external clock, 6T
0.32F + 2.3
mA
VDD = 5.0V, internal 22.1184MHz, 12T
4.8
mA
VDD = 3.3V, internal 11.0592MHz, 12T
3.4
mA
VDD = 5.0V, internal 22.1184MHz, 6T
7.0
mA
VDD = 3.3V, internal 11.0592MHz, 6T
4.5
mA
VDD = 5.0V, external clock, 12T
0.11F + 2.0
mA
VDD = 3.3V, external clock, 12T
0.09F + 0.9
mA
VDD = 5.0V, external clock, 6T
0.15F + 1.7
mA
VDD = 3.3V, external clock, 6T
0.14F + 0.7
mA
VDD = 5.0V, internal 22.1184MHz, 12T
1.5
mA
VDD = 3.3V, internal 11.0592MHz, 12T
1.2
mA
VDD = 5.0V, internal 22.1184MHz, 6T
2.0
mA
VDD = 3.3V, internal 11.0592MHz, 6T
1.4
mA
35
μA
800
kΩ
IDD
Supply current
Idle mode current
Max.
μA
Input leakage current (Port 0) 0 < VIN < VDD
IID
Typ.
-50
-20
ILI
[3]
Min.
-570
-240
IPD
Power Down mode current
2
RRST
RST pin internal pull-down
resistor
VBOD0
Brown-out threshold 2.2V
2.05
2.2
2.3
V
VBOD1
Brown-out threshold 2.7V
2.6
2.7
2.85
V
VBOD2
Brown-out threshold 3.8V
3.65
3.8
4.0
V
VBOD3
Brown-out threshold 4.5V
4.35
4.5
4.75
V
200
mV
2.4 < VDD < 5.5V
VBODHYS Brown-out hysteresis
VPOR
45
20
Power-on reset threshold
2.0
V
[1] Under steady state (non-transient) conditions, IOL must be externally limited as follows:
Maximum IOL per port pin :
20mA
Maximum IOL per 8-bit port :
40mA
Maximum total IOL for all outputs: 100mA
[2] Pins of Ports 1-4 and Port 0 with internal pull-up enabled will source a transition current when they are being externally
driven from 1 to 0. The transition current reaches its maximum value when VIN is approximately 1.5V to 2.5V.
[3] It is measured while MCU keeps in running SJMP $ loop continuously. P0 is externally or internally pulled-up.
- 126 -
Figures below shows supply and Idle mode current under 12T/6T with internal program memory mode.
Figure 26–1. Supply Current Under 12T Mode, External Clock (1)
- 127 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Figure 26–2. Supply Current Under 12T Mode, External Clock (2)
Figure 26–3. Supply Current Under 6T Mode, External Clock (1)
Figure 26–4. Supply Current Under 6T Mode, External Clock (2)
- 128 -
Figure 26–5. Idle Mode Current Under 12T Mode, External Clock (1)
Figure 26–6. Idle Mode Current Under 12T Mode, External Clock (2)
- 129 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Figure 26–7. Idle Mode Current Under 6T Mode, External Clock (1)
Figure 26–8. Idle Mode Current Under 6T Mode, External Clock (2)
- 130 -
26.3 AC Electrical Characteristics
Table 26–2. AC Characteristics
12T mode
Symbol
6T mode
Parameter
Unit
Min.
Max.
Min.
Max.
External clock input frequency
0
40
0
33
Crystal/resonator frequency
4
40
4
33
tCHCX
High time
12
15
ns
tCLCX
Low time
12
15
ns
tCLCH
Rise time
8
5
ns
tCHCL
Fall time
8
5
ns
External Clock
1/ tCLCL
MHz
Program Memory
tLHLL
ALE pulse width
2 tCLCL -15
tCLCL -15
ns
tAVLL
Address valid to ALE low
tCLCL -15
0.5 tCLCL -15
ns
tLLAX
Address hold after ALE low
tCLCL -15
0.5 tCLCL -15
ns
tLLIV
ALE low to valid instruction in
tLLPL
ALE low to PSEN low
tPLPH
PSEN pulse width
tPLIV
PSEN low to valid instruction in
tPXIX
Input instruction hold after PSEN
tPXIZ
Input instruction float after PSEN
tAVIV
Address to valid instruction in
tPLAZ
PSEN low to address float
4 tCLCL -45
2 tCLCL -45
ns
tCLCL -15
0.5 tCLCL -15
ns
3 tCLCL -15
1.5 tCLCL -15
ns
3 tCLCL -50
0
1.5 tCLCL -50
0
ns
ns
tCLCL -15
0.5 tCLCL -15
ns
5 tCLCL -60
2.5 tCLCL -60
ns
10
10
ns
Data Memory
tRLRH
RD pulse width
6 tCLCL -30
3 tCLCL -30
ns
tWLWH
WR pulse width
6 tCLCL -30
3 tCLCL -30
ns
tRLDV
RD low to valid data in
tRHDX
Data hold after RD
tRHDZ
Data float after RD
2 tCLCL -12
tCLCL -12
ns
tLLDV
ALE low to valid data in
8 tCLCL -50
4 tCLCL -50
ns
tAVDV
Address to valid data in
9 tCLCL -75
4.5 tCLCL -75
ns
tLLWL
ALE low to RD or WR low
1.5 tCLCL +15
ns
5 tCLCL -50
0
2.5 tCLCL -50
0
3 tCLCL -15
- 131 -
3 tCLCL +15
1.5 tCLCL -15
ns
ns
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
12T mode
Symbol
6T mode
Parameter
Unit
Min.
tAVWL
Address valid to WR low or RD low
tQVWX
Max.
Min.
Max.
4 tCLCL -30
2 tCLCL -30
ns
Data valid to WR transition
tCLCL -20
0.5 tCLCL -20
ns
tWHQX
Data hold after WR
tCLCL -15
0.5 tCLCL -15
ns
tRLAZ
RD low to address float
tWHLH
RD or WR high to ALE high
0
tCLCL -15
tCLCL +15
0.5 tCLCL -15
Figure 26–9. External Clock Input Timing
Figure 26–10. External Program Memory Read Cycle
- 132 -
0
ns
0.5 tCLCL +15
ns
Figure 26–11. External Data Memory Read Cycle
Figure 26–12. External Data Memory Write Cycle
- 133 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Table 26–3. Characteristics of On-chip RC Oscillators
Symbol
Parameter
Condition
Frequency
Deviation
Min.
Typ.
FIHRC
System 22.1184MHz RC oscillator
[1][2]
frequency
TA = 25℃
1%
21.8972
22.1184
22.3396 MHz
TA = -40℃ to +85℃
3%
21.4548
22.1184
22.7820 MHz
30%
7
10
FILRC
WDT and PDT 10kHz RC oscillator
frequency
Max.
13
Unit
kHz
[1] Internal 11.0592MHz is not listed for the same frequency deviation due to directly divided by 2 from 22.1184MHz
source.
[2] A 0.1μF capacitor is recommended to be added on XTAL1 pin to gain the more precise frequency of the internal RC
oscillator frequency if it is selected as the system clock source.
Table 26–4. Characteristics of Brown-out Detection
Symbol
TBOD
TBODRD
Parameter
Condition
Min.
Typ.
Max.
Unit
Brown-out detect pulse width
VDD < VBOD
600
-
-
μs
Brown-out release delay period
VDD > VBOD
5.6
8
10.4
ms
- 134 -
27. PACKAGES
D
40
21
1
20
1
E
E
S
c
2
1
AA
A
Base Plane
Seating Plane
L
B
e1
α
B1
Symbol
A
A1
A2
B
B1
c
D
E
E1
e1
L
α
eA
S
Dimension in inch
eA
Dimension in mm
Min Nom Max Min Nom Max
5.33
0.210
0.010
0.25
0.150 0.155 0.160
3.81
3.94
4.06
0.016 0.018 0.022
0.41
0.46
0.56
0.048 0.050 0.054
1.22
1.27
1.37
0.008 0.010 0.014
0.20
0.25
0.36
2.055 2.070
52.20 52.58
0.590 0.600 0.610 14.99 15.24 15.49
0.540 0.545 0.550 13.72 13.84 13.97
0.090 0.100 0.110
2.29
2.54
2.79
0.120 0.130 0.140
3.05
3.30
3.56
0
15
0
15
0.630 0.650 0.670 16.00 16.51 17.02
0.090
2.29
Figure 27–1. DIP-40 Package Dimention
- 135 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
HD
D
6
1
44
40
7
39
E
E
E H
17
G
29
18
28
c
L
2
A
e
1
b
b1
Seating Plane
A
A
y
GD
Symbol
A
A1
A2
b1
b
c
D
E
e
GD
GE
HD
HE
L
y
Dimension in inch
Min
Nom
Dimension in mm
Max
Min
Nom
0.185
Max
4.70
0.020
0.51
0.145
0.150
0.155
3.68
3.81
3.94
0.026
0.028
0.032
0.66
0.71
0.81
0.016
0.018
0.022
0.41
0.46
0.56
0.008
0.010
0.014
0.20
0.25
0.36
0.648
0.653
0.658
16.46
16.59
16.71
0.648
0.653
0.658
16.46
16.59
16.71
0.050
1.27
BSC
BSC
0.590
0.610
0.630
14.99
15.49
16.00
0.590
0.610
0.630
14.99
15.49
16.00
0.680
0.690
0.700
17.27
17.53
17.78
0.680
0.690
0.700
17.27
17.53
17.78
0.090
0.100
0.110
2.29
2.54
2.79
0.004
0.10
Figure 27–2. PLCC-44 Package Dimention
- 136 -
HD
D
34
44
33
1
E
E H
11
12
e
b
22
c
2
A A
Seating Plane
1
See Detail F
L
A
y
L1
Symbol
A
A1
A2
b
c
D
E
e
HD
HE
L
L1
y
0
Dimension in inch
Dimension in mm
Min Nom Max
Min Nom Max
-
0.002
0.01
0.02
0.05
0.25
0.5
0.075
0.081
0.087
1.90
2.05
2.20
0.01
0.014
0.018
0.25
0.35
0.45
0.004
0.006
0.010
0.10
0.15
0.390 0.394
0.398
9.9
10.00
10.1
0.390 0.394
0.398
9.9
10.00
10.1
.0315
0.25
0.80
0.510 0.520
0.530
12.95
13.20
13.45
0.510 0.520
0.530
12.95
13.20
13.45
0.025 0.031
0.037
0.65
0.8
0.95
1.60
0.063
0.10
0.004
0
Detail F
10
0
10
Figure 27–3. PQFP-44 Package Dimention
- 137 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
Figure 27–4. TQFP-44 Package Dimention
- 138 -
Figure 27–5. LQFP-48 Package Dimention
- 139 -
Publication Release Date: September 4, 2012
Revision: V2.2
N78E517A Data Sheet
28. DOCUMENT REVISION HISTORY
Version
Date
Page
Description
V1.0
2010/8/13
Initial release.
V1.1
2010/9/20
126
V1.2
2010/12/1
81
96
88
1.
2.
3.
V2.0
2011/3/11
30
Change XRAM default state “enabled” after all resets to fit general applications.
V2.1
2011/9/9
V2.2
2012/9/4
Increase the maximum value of Power Down mode current.
1.
2.
138
Add restriction of disabling interrupts during TA protected writing.
Add restriction of disabling interrupts during ISP.
Add more description of software clearing interrupt flags.
TQFP-44 package available.
Correct some typo errors.
Correct TQFP-44 package dimension.
Technical Supporting Web
80C51 8-bit MCU Series
http://www.nuvoton.com/80C51
- 140 -
More product details and update information, please visit our website:
www.nuvoton.com
Headquarter-Taiwan
Nuvoton Technology Corp.
No. 4, Creation Rd. Ill, Hsinchu Science Park,
300 Taiwan
TEL: 886-3-5770066
Worldwide Sales Offices
Taipei Sales Office
Nuvoton Technology Corp. America
8F, No. 480, Rueiguang Rd., Neihu Chiu, Taipei,
114 Taiwan
TEL: 886-2-26588066
2727 N. First Street, San Jose, CA 95134, U.S.A.
TEL: 1-408-544-1718
Nuvoton Electronics Tech. (Shenzhen) Limited
Nuvoton Electronics Tech. (H.K.) Limited
Unit 1501, New World Center, 6009 Yitian Road,
Futian, Shenzhen, P.R.China 518026
TEL: 86-755-83515350
Unit 9-11, 22F, Millennium City 2, 378 Kwun Tong Road,
Kowloon, Hong Kong
TEL: 852-27513100
Important Notice
Nuvoton Products are neither intended nor warranted for usage in systems or equipment, any malfunction or failure of which may cause loss of human life, bodily injury or severe property damage. Such
applications are deemed, “Insecure Usage”.
Insecure usage includes, but is not limited to: equipment for surgical implementation, atomic energy
control instruments, airplane or spaceship instruments, the control or operation of dynamic, brake or
safety systems designed for vehicular use, traffic signal instruments, all types of safety devices, and
other applications intended to support or sustain life.
All Insecure Usage shall be made at customer’s risk, and in the event that third parties lay claims to
Nuvoton as a result of customer’s Insecure Usage, customer shall indemnify the damages and liabilities thus incurred by Nuvoton.
- 141 -
Publication Release Date: September 4, 2012
Revision: V2.2
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