MC3479 3-Axis Accelerometer
GENERAL DESCRIPTION
FEATURES
The MC3479 is a small form factor,
integrated digital output 3-axis
accelerometer with a feature set optimized
for cell phones and consumer product
motion sensing. Applications include user
interface control, gaming motion input,
electronic compass tilt compensation for
cell phones, game controllers, remote
controls and portable media products.
Range, Sampling & Power
•
•
•
•
•
•
•
•
•
•
Low power consumption and small size are
inherent in the monolithic fabrication
approach, where the MEMS accelerometer
is integrated in a single-chip with the
electronics integrated circuit.
•
SPI, up to 10 MHz
I2C interface, up to 1 MHz
2×2×0.92 mm 12-pin LGA package
High reliability thru single-chip 3D
silicon MEMS technology
RoHS compliant
Applications
•
•
•
•
•
•
In the MC3479 the internal sample rate can
be set from 0.5 to 2000 samples / second.
The device supports the reading of sample
and event status via polling or interrupts.
Information furnished by MEMSIC is believed to be accurate and reliable.
However, no responsibility is assumed by MEMSIC for its use, or for any
infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any
patent or patent rights of MEMSIC.
±2, ±4, ±8, ±12, ±16g range
16-bit single sample resolution
16-bit resolution with FIFO
0.5 to 2000 Hz Output Data Rate
4 μA typical Standby current
Low typical active current
Simple System Integration
The MC3479 features a dedicated motion
block which implements algorithms to
support “any motion” and shake detection,
tilt/flip and tilt 35 position detection.
MEMSIC MC3479 APS-048-0072 v1.12
Final Datasheet
Smartphone
Wearable
IoT & IoMT
Remote controls, gaming
Vibration in Cell phone
VR & game controllers
www.memsic.com
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TABLE OF CONTENTS
1
Order Information............................................................................................................. 5
2
Functional Block Diagram ................................................................................................ 6
3
Packaging and Pin Description ........................................................................................ 7
3.1
Package Outline ................................................................................................................... 7
3.2
Package Orientation ............................................................................................................. 8
3.3
Pin Description ..................................................................................................................... 9
3.4
Typical Application Circuits ................................................................................................ 10
3.5
Tape and Reel ................................................................................................................... 13
3.6
Soldering Profile ................................................................................................................. 15
3.7
Shipping and Handling Guidelines ..................................................................................... 15
3.8
Moisture Sensitivity Level Control ...................................................................................... 15
4
Specifications................................................................................................................. 16
4.1
Absolute Maximum Ratings ................................................................................................ 16
4.2
Sensor Characteristics ....................................................................................................... 17
4.3
Electrical and Timing Characteristics.................................................................................. 18
4.3.1 Electrical Power and Internal Characteristics ..................................................................... 18
4.3.2 Electrical Characteristics .................................................................................................... 19
4.3.3 I2C Timing Characteristics ................................................................................................. 20
4.3.4 SPI Timing Characteristics ................................................................................................. 21
5
General Operation ......................................................................................................... 22
5.1
Sensor Sampling ................................................................................................................ 22
5.2
Offset and Gain Calibration ................................................................................................ 22
6
Operational States ......................................................................................................... 23
7
Operational State Flow .................................................................................................. 24
8
Interrupts........................................................................................................................ 25
8.1
Interrupt Overview .............................................................................................................. 25
8.2
Enabling and Clearing Interrupts ........................................................................................ 26
8.3
Interrupt Sources................................................................................................................ 26
8.3.1 ACQ_INT Interrupt ............................................................................................................. 26
8.3.2 TILT/FLIP (TILT_INT, FLIP_INT) ........................................................................................ 26
8.3.3 Interrupt on AnyMotion (ANYM_INT) .................................................................................. 26
8.3.4 Interrupt on SHAKE (SHAKE_INT) ..................................................................................... 26
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8.3.5 Interrupt on TILT_35 (TILT_35_INT) .................................................................................. 27
8.3.6 Interrupt on FIFO Empty (FIFO_EMPTY_INT) ................................................................... 27
8.3.7 Interrupt on FIFO Full (FIFO_FULL_INT) ........................................................................... 27
8.3.8 Interrupt on FIFO Threshold (FIFO_THRESH_INT) ........................................................... 27
8.4
Interrupt Servicing .............................................................................................................. 28
8.4.1 Global Interrupt Service method ......................................................................................... 28
8.4.2 Bitmask/Individual Interrupt Service Mode.......................................................................... 28
8.5
Interrupt Requests and External INT Pins .......................................................................... 30
8.5.1 Selecting Drive and Polarity ............................................................................................... 30
8.5.2 Swapping INT Pins............................................................................................................. 31
8.5.3 Combining Interrupt Requests ............................................................................................ 31
9
Sampling ........................................................................................................................ 32
9.1
Continuous Sampling ......................................................................................................... 32
9.2
Setting the Sample Rate .................................................................................................... 32
9.3
Additional Rate Options...................................................................................................... 33
10
I2C Interface .................................................................................................................. 35
10.1
Physical Interface ............................................................................................................... 35
10.2
Timing ................................................................................................................................ 36
10.3
I2C Message Format .......................................................................................................... 36
10.4
I2C Watchdog Timer .......................................................................................................... 37
11
SPI Interface .................................................................................................................. 38
11.1
SPI Physical Interface ........................................................................................................ 38
11.2
SPI Protocol ....................................................................................................................... 38
11.3
SPI Register Write Cycle - Single ....................................................................................... 38
11.4
SPI Register Write Cycle - Burst ........................................................................................ 38
11.5
SPI Register Read Cycle - Single ....................................................................................... 39
11.6
SPI Register Read Cycle - Burst ........................................................................................ 39
11.7
Timing ................................................................................................................................ 40
12
Register Interface .......................................................................................................... 41
12.1
Register Summary ............................................................................................................. 41
12.2
(0x05)Device Status Register ............................................................................................. 44
12.3
(0x06) Interrupt Enable Register ........................................................................................ 45
12.4
(0x07) Mode Register ......................................................................................................... 46
12.5
(0x08) Sample Rate Register ............................................................................................. 47
12.6
(0x09) Motion Control Register........................................................................................... 48
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12.7
(0x0A) FIFO Status Register .............................................................................................. 49
12.8
(0x0B) FIFO Read Pointer Register.................................................................................... 50
12.9
(0x0C) FIFO Write Pointer Register.................................................................................... 51
12.10
(0x0D - 0x12) XOUT, YOUT and ZOUT Data Accelerometer Registers ............................. 52
12.11
(0x13) Status Register........................................................................................................ 53
12.12
(0x14) Interrupt Status Register ......................................................................................... 54
12.13
(0x20) Range and Scale Control Register .......................................................................... 55
12.14
(0x21 – 0x22) X-Axis Digital Offset Registers ..................................................................... 56
12.15
(0x23 – 0x24) Y-Axis Digital Offset Registers ..................................................................... 57
12.16
(0x25 – 0x26) Z-Axis Digital Offset Registers ..................................................................... 58
12.17
(0x22 & 0x27) X-Axis Digital Gain Registers ...................................................................... 59
12.18
(0x24 & 0x28) Y-Axis Digital Gain Registers ...................................................................... 60
12.19
(0x26 & 0x29) Z-Axis Digital Gain Registers....................................................................... 61
12.20
(0x2D) FIFO Control Register............................................................................................. 62
12.21
(0x2E) FIFO Threshold Register ........................................................................................ 64
12.22
(0x2F) FIFO Interrupt Status Register ................................................................................ 65
12.23
(0x30) FIFO Control Register2, Sample Rate Register 2 .................................................... 66
12.24
(0x31) Communication Control Register ............................................................................. 68
12.25
(0x33) GPIO Control Register ............................................................................................ 69
12.26
(0x40 – 0x41) Tilt/Flip Threshold Registers ........................................................................ 70
12.27
(0x42) Tilt/Flip Debounce Register ..................................................................................... 71
12.28
(0x43 – 0x44) AnyMotion Threshold Registers ................................................................... 72
12.29
(0x45) AnyMotion Debounce Register ................................................................................ 73
12.30
(0x46 – 0x47) Shake Threshold Registers.......................................................................... 74
12.31
(0x48 – 0x49) Shake Duration, Peak-to-Peak Registers..................................................... 75
12.32
(0x4A) Timer Control Register ............................................................................................ 76
12.33
(0x4B) Read Count Register .............................................................................................. 77
13
Index of Tables .............................................................................................................. 78
14
Revision History ............................................................................................................. 80
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1 ORDER INFORMATION
Table 1. Order Information
Part Number
Resolution
Order Number
Package
Shipping
MC3479
16-bit
MC3479
VLGA-12
Tape & Reel, 10Ku
Table 2. Package Information
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2 FUNCTIONAL BLOCK DIAGRAM
Sensors
VDD
Oscillator /
Clock
Generator
Regulators
and Bias
INTN2
Mode Logic
Motion
Event
Detect
X
Interrupts
INTN1
FIFO
32 x 48
SCL_SCK
Y
C to V
Sigma
Delta
Accum./
Filter
XYZ
data
paths
LPF
Offset/
Gain
Adjust
Range
and
Scale
Registers
(80x8)
I2C/SPI
Interface
DIN_SDA
(MOSI)
DOUT_A6
(MISO)
CSN
GND
Z
OTP
Memory
VPP
Figure 1. Block Diagram
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3 PACKAGING AND PIN DESCRIPTION
3.1 PACKAGE OUTLINE
Figure 2. Package Outline and Mechanical Dimensions
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3.2 PACKAGE ORIENTATION
Top View
a.
Direction of
Earth gravity
acceleration
Top
Pin 1
Side View
e.
b.
XOUT = +1g
YOUT = 0g
ZOUT = 0g
c.
XOUT = 0g
YOUT = 0g
ZOUT = +1g
f.
XOUT = 0g
YOUT = -1g
ZOUT = 0g
d.
XOUT = 0g
YOUT = +1g
ZOUT = 0g
XOUT = 0g
YOUT = 0g
ZOUT = -1g
XOUT = -1g
YOUT = 0g
ZOUT = 0g
Figure 3. Package Orientation
+Z
+X
+Y
-Y
-X
-Z
Figure 4. Package Axis Reference
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3.3 PIN DESCRIPTION
Pin
Name
Function
1
SCK_SCL 1
I2C/SPI serial clock input
2
CSN
3
DOUT_A6
4
DIN_SDA 1
5
NC
No connect
6
GND
Ground
7
VPP
Connect to GND
8
NC
No connect
9
VDD
Power supply for internal
10
NC
No Connect
11
INTN 2 2,3
Interrupt active LOW 3
12
INTN 1 2,3
Interrupt active LOW 3
SPI chip select (active low)
I2C must connect to Vdd
SPI data output
I2C address bit 6
SPI data In
I2C serial data input/output
Table 3. Pin Description
Notes:
1) This pin requires a pull-up resistor, typically 4.7kΩ to pin VDD. Refer to I2C
Specification for Fast-Mode devices. Higher resistance values can be used (typically
done to reduce current leakage) but such applications are outside the scope of this
datasheet.
2) This pin can be configured by software to operate either as an open-drain output or
push-pull output (see GPIO control register, address 0x33). If set to open-drain, then it
requires a pull-up resistor, typically 4.7kΩ to VDD.
3) INTN pin polarity is programmable in the GPIO control register, address 0x33.
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3.4 TYPICAL APPLICATION CIRCUITS
}
To Fast-Mode I2C
circuitry1
1
10
SCK_SCL NC
Rp
Rp
3 DOUT_A6
4 DIN_SDA
CSN 2
GND 6
5 NC
7 VPP
NC 8
VDD 9
0.1µF
Rp
Rp
INTN1
12
(optional) To MCU
interrupt input2
From power
supply
INTN2
11
Place cap close
to VDD and
GND on PCB
NOTE1: Rp are typically 4.7kΩ pullup resistors to VDDIO, per I2C specification. When
VDDIO is powered down, DIN_SDA and SCK_SCL will be driven low by internal
ESD diodes.
NOTE2: Attach typical 4.7kΩ pullup resistor if INTN is defined as open-drain.
Figure 5. Typical I2C Application Circuit
In typical applications, the interface power supply may contain significant noise from external
sources and other circuits which should be kept away from the sensor. Therefore, for some
applications a lower-noise power supply might be desirable to power the VDD pin.
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To 4-wire
SPI master
1
10
SCK_SCL NC
3 DOUT_A6
4 DIN_SDA
CSN 2
GND 6
5 NC
7 VPP
NC 8
VDD 9
0.1µF
Rp
Rp
From
power
supply
INTN1 INTN2
(optional)
To MCU
interrupt input
12
11
Place cap close
to VDD and
GND on PCB
NOTE Rp: Attach typical 4.7kΩ pullup resistor if INTN is defined as open-drain.
Figure 6. Typical 4-wire SPI Application Circuit
MEMSIC MC3479 APS-048-0072 v1.12
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To 3-wire
SPI master
1
10
SCK_SCL NC
3 DOUT_A6
4 DIN_SDA
CSN 2
GND 6
5 NC
7 VPP
NC 8
VDD 9
0.1µF
Rp
Rp
INTN1
(optional)
To MCU
interrupt input
12
From
power
supply
INTN2
11
Place cap close
to VDD and
GND on PCB
NOTE Rp: Attach typical 4.7kΩ pullup resistor if INTN is defined as open-drain.
Figure 7. Typical 3-wire SPI Application Circuit
MEMSIC MC3479 APS-048-0072 v1.12
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3.5 TAPE AND REEL
Devices are shipped in reels, in standard cardboard box packaging. See Figure 8. MC3479
Tape Dimensions and Figure 9. MC3479 Reel Dimensions.
•
Dimensions in mm.
•
10 sprocket hole pitch cumulative tolerance ±0.2
•
Pocket position relative to sprocket hole measured as true position of pocket, not pocket
hole.
Figure 8. MC3479 Tape Dimensions
MEMSIC MC3479 APS-048-0072 v1.12
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•
Dimensions in mm.
Figure 9. MC3479 Reel Dimensions
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3.6 SOLDERING PROFILE
The LGA package follows the reflow soldering classification profiles described in Joint Industry
Standard, Moisture/Reflow Sensitivity Classification for Nonhermetic Surface Mount Devices,
document number J-STD-020E. Reflow soldering has a peak temperature (Tp) of 260⁰C
3.7 SHIPPING AND HANDLING GUIDELINES
Shipping and handling follow the standards described in Joint Industry Standard, Handling,
Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount Devices, document
number J-STD-033C.
The following are additional handling guidelines (refer to the MEMSIC document, PCB Design,
Device Handling and Assembly Guidelines, for more information):
•
•
•
•
While the mechanical sensor is designed to handle high-g shock events, direct
mechanical shock to the package should be avoided.
SMT assembly houses should use automated assembly equipment with either plastic
nozzles or nozzles with compliant tips (for example, soft rubber or silicone).
Avoid g-forces beyond the specified limits during transportation.
Handling and mounting of sensors should be done in a defined and qualified installation.
3.8 MOISTURE SENSITIVITY LEVEL CONTROL
The following are storage recommendations (refer to the MEMSIC document, PCB Design,
Device Handling and Assembly Guidelines, for more information):
•
•
•
Store the tape and reel in the unopened dry pack, until required on the assembly floor.
If the dry pack has been opened or the reel has been removed from the dry pack, reseal
the reel inside of the dry pack with a black protective belt. Avoid crushing the tape and
reel.
Store the cardboard box in a vertical position.
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4 SPECIFICATIONS
4.1 ABSOLUTE MAXIMUM RATINGS
Parameters exceeding the Absolute Maximum Ratings may permanently damage the device.
Rating
Symbol
Minimum /
Maximum Value
Unit
Supply Voltages
Pin VDD
-0.3 / +3.6
V
Ambient operating temperature
TOP
-40 / +85
⁰C
Storage temperature
TSTG
-40 / +125
⁰C
ESD human body model
HBM
± 2000
V
Latch-up current at Top = 25 ⁰C
ILU
100
mA
Input voltage to non-power pin
Pins CSN,
DIN_SDA,
DOUT_A6, INTN 1,
INTN 2, and
SCK_SCL
-0.3 / (VDD + 0.3) or
3.6 whichever is lower
V
Table 4. Absolute Maximum Ratings
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4.2 SENSOR CHARACTERISTICS
VDD = 2.8V, Top = 25 ⁰C unless otherwise noted
Parameter
Conditions
Min
Sensitivity Temperature
Coefficient 1
RMS Noise
Nonlinearity 1
Cross-axis Sensitivity 1
g
16384
Acceleration range = ±4.0g
8192
Acceleration range = ±8.0g
4096
Acceleration range = ±12.0g
2730
Acceleration range = ±16.0g
2048
-40 ≤ Top ≤ +85 ⁰C
±0.025
%/⁰C
Chip Level
Board Level
±20
±50
mg
-40 ≤ Top ≤ +85 ⁰C
±1
mg/⁰C
ODR = 125 Hz, LPF = ODR/16
0.7 (X,Y)
1.3 (Z)
mg
RMS
Acceleration range = ±2.0g
0.6
% FS
Between any two axes
±2
%
ODR, Output Data Rate
1
Unit
Acceleration range = ±2.0g
Zero-g Offset
Zero-g Offset
Temperature Coefficient 1
Max
±2.0
±4.0
±8.0
±12.0
±16.0
Acceleration range
Sensitivity
Typ
0.5
LSB/g
2000
Hz
Values are based on device characterization, not tested in production.
Table 5. Sensor Characteristics
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4.3 ELECTRICAL AND TIMING CHARACTERISTICS
4.3.1 ELECTRICAL POWER AND INTERNAL CHARACTERISTICS
Parameter
Supply voltage 1
Conditions
Symbol
Min
Pin VDD
VDD
Tclock
Sample Rate Tolerance 2
1
Min and Max limits are hard limits without additional tolerance.
2
Values are based on device characterization, not tested in production.
Typ
Max
Unit
1.7
3.6
V
-2
2
%
Test condition: VDD = 2.8V, Top = 25 ⁰C unless otherwise noted
Parameter
Conditions
Min
Standby current
WAKE state current
Pad Leakage
ODR = 100 Hz
Per I/O pad
-1
Typ
Max
Unit
4
μA
77
μA
0.01
1
μA
Wake-Up time
3
ms
Start-Up time
1/ODR+1mS
ms
Table 6. Electrical Characteristics
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4.3.2 ELECTRICAL CHARACTERISTICS
Parameter
Symbol
Min
Max
Unit
LOW level input voltage
VIL
-0.5
0.3*VDD
V
HIGH level input voltage
VIH
0.7*VDD
-
V
Hysteresis of Schmitt trigger inputs
Vhys
0.05*VDD
-
V
Vol
0
0.4
V
Voh
0
0.9*VDD
V
Vols
-
0.1*VDD
V
Ii
-10
10
µA
Ci
-
10
pF
Output voltage, pin INTN 1 or INTN 2, Iol ≤ 2 mA
Output voltage, pin DIN_SDA (open drain),
Iol ≤ 1 mA
Input current, pins DIN_SDA and SCK_SCL
(input voltage between 0.1*VDD and 0.9*VDD
max)
Capacitance, pins DIN_SDA and SCL 1
1
Values are based on device characterization, not tested in production.
Table 7. Electrical and Timing Characteristics - Interface
NOTES:
•
•
If multiple slaves are connected to the I2C signals in addition to this device, only 1 pullup resistor on each of DIN_SDA and SCK_SCL should exist. Also, care must be taken
to not violate the I2C specification for capacitive loading.
When pin VDD is disconnected from power or ground (e.g. Hi-Z), the device may
become inadvertently powered up through the ESD diodes present on other powered
signals.
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4.3.3 I2C TIMING CHARACTERISTICS
Figure 10. I2C Interface Timing
Parameter
fSCL
tHD; STA
tLOW
tHIGH
tSU;STA
tHD;DAT
tSU;DAT
tSU;STO
tBUF
Description
SCL clock frequency
Hold time (repeated) START
condition
LOW period of the SCL clock
HIGH period of the SCL clock
Set-up time for a repeated START
condition
Data hold time
Data set-up time
Set-up time for STOP condition
Bus free time between a STOP and
START
Standard
Mode
Min
Max
0
100
Fast Mode
Min
Max
0
400
Fast Mode
Plus
Min
Max
0
1000
4.0
-
0.6
-
0.26
-
μs
4.7
4.0
-
1.3
0.6
-
0.5
0.26
-
μs
μs
4.7
-
0.6
-
0.26
-
μs
5.0
250
4.0
-
100
0.6
-
50
0.26
-
μs
ns
μs
4.7
-
1.3
-
0.5
-
μs
Units
kHz
Table 8. I2C Timing Characteristics
NOTE: Values are based on I2C Specification requirements, not tested in production.
See also Section 10.3 I2C Message Format.
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4.3.4 SPI TIMING CHARACTERISTICS
DOUT_A6
Figure 11. SPI Interface Timing Waveform
Symbol
Parameter
Value
Min
Units
Max
tc
SPI SCK_SCL Clock Cycle
500
ns
fc
SPI SCK_SCL Clock Frequency
tcs_su
SPI CSN Setup Time
6
ns
tcs_hld
SPI CSN Hold Time
8
ns
tdi_su
SPI DIN_SDA Input Setup Time
5
ns
tdi_hld
SPI DIN_SDA Input Hold Time
15
ns
tdo_vld
SPI DOUT_A6 Valid Output Time
tdo_hld
SPI DOUT_A6 Output Hold Time
tdo_dis
SPI DOUT_A6 Output Disable Time
10
50
9
MHz
ns
ns
50
ns
Table 9. SPI Interface Timing Parameters
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5 GENERAL OPERATION
The device supports the reading of samples and device status upon interrupt or by polling.
5.1 SENSOR SAMPLING
In the WAKE state, acceleration data for X, Y, and Z axes is sampled at a rate between 0.5
and 2000 samples/second. See the Sample Rate Register section.
The detectable acceleration range is variable and is set in the RANGE bits of the range and
scale control register.
Acceleration Value per
Resolution
bit
Range
(mg/LSB)
16-bit
Full Scale
Negative
Reading
Full Scale
Positive
Reading
± 2g
~.061
0x8000
0x7FFF
± 4g
~.122
(-32768)
(+32767)
± 8g
~.244
± 12g
~.366
± 16g
~.488
Comments
Signed 2’s complement
number, results in
XOUT_EX, YOUT_EX,
ZOUT_EX. The MSB is
the sign bit.
(Integer interpretation
also shown)
Table 10. Summary of Resolution, Range, and Scaling
5.2 OFFSET AND GAIN CALIBRATION
Digital offset and gain calibration can be performed on the sensor, if necessary, in order to
reduce the effects of post-assembly influences and stresses which may cause the sensor
readings to be offset from their factory values.
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6 OPERATIONAL STATES
The device has two states of operation: STANDBY and WAKE. All states are controlled by the
software, there is no automatic power control.
The device defaults to the STANDBY state following a power-up and must be in the WAKE
state before executing a reset.
The time to change from the STANDBY to WAKE state takes one sample period (takes less
than 10 µs).
State
STANDBY
WAKE
I2C/SPI
Bus
R/W
Description
•
Lowest power consumption
•
Internal clocking is halted
•
No motion detection, sampling, or calibration
•
The I2C/SPI bus can read and write to registers (resolution, range,
thresholds and other settings can be changed)
•
Reset not allowed
•
Default state after a power-up
•
Highest power consumption
•
Internal clocking is enabled
•
Continuous motion detection and sampling; automatic calibration is
available
•
The I2C/SPI bus can only write to the mode register and read all other
registers
•
Reset allowed
R
Table 11. Operational States
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7 OPERATIONAL STATE FLOW
Figure 12. Operational State Flow shows the operational state flow for the device. The
device defaults to STANDBY following power-on.
STANDBY
STATE=00
STATE=01
WAKE
Figure 12. Operational State Flow
The operation state may be read from the STATE bits of the device status register. The
operational state may be forced to a specific state by writing into the STATE bits of the mode
register, as shown below. Two bits are specified in order to promote software compatibility
with other MEMSIC devices. The operational state will stay in the mode specified until
changed.
Action
Setting
Effect
Force STANDBY State
STATE[1:0] = 00
Force WAKE State
STATE[1:0] = 01
•
•
•
•
Switch to the STANDBY state and stay there
Disable sensor and event sampling
Switch to WAKE state and stay there
Continuous sampling
Table 12. Forcing Operational States
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8 INTERRUPTS
The sensor device utilizes output pin INTN 1 or INTN 2 to signal to an external microprocessor
that an event has been detected. The microprocessor should contain an interrupt service
routine which would perform certain tasks after receiving this interrupt and reading the
associated status bits, perhaps after a sample was made ready. If interrupts are to be used,
the microprocessor must set up the registers in the sensor so that when a specific event is
detected, the microprocessor would receive the interrupt and the interrupt service routine
would be executed. If polling is used, there is no need for the interrupt registers to be set up.
For products that use polling, the microprocessor must periodically poll the sensor and read
the status data (the INTN 1 or INTN 2 pin is not used). For most applications, this is likely best
done at the sensor sampling rate or faster.
NOTE: At least one I2C STOP condition must be present between samples for the sensor to
update the sample data registers.
8.1 INTERRUPT OVERVIEW
Feature
Description
Comment
Interrupt Pins
Two interrupt pins are supported:
INTN1
INTN2
INTN1 defaults to open-drain mode, active
low polarity, and transitions on
SAMPLE+MOTION interrupt events.
INTN2 defaults to open-drain mode, active
low polarity, and transitions on FIFO
interrupt events
Interrupt Polarity
INTN1 and INTN2 pins operate in
open-drain and active-drive modes.
The polarity of the interrupts is
independently selectable.
The interrupt polarity/drive mode bits are
in the GPIO control register 0x33.
Interrupt Sources
1 interrupt on sample
5 motion interrupts
3 FIFO interrupts
The default setting is to route
SAMPLE+MOTION interrupt requests
(INT1_REQ) to INTN1 pin and FIFO
interrupt requests (INT2_REQ) to the
INTN2 pin.
Interrupt Servicing
Interrupts may be cleared globally or
individually. All interrupts are cleared
by writing to register 0x14. FIFO
interrupt bits are loaded in register
0x2F.
Global clearing is the default, use register
0x31 bit 6 (INDIV_INTR_CLR) to enable the
individual interrupt clear option (bitmask
mode). Read/writing to register 0x2F does
not clear FIFO interrupts.
Swapping or Combining
Interrupt Requests
INT1_REQ (sample + motion) and
INT2_REQ (FIFO) may be swapped
between the INTN1 and INTN2 pins or
combined on a single INTN1 pin.
If all interrupts are combined in a single
source, the pin to be used can still be
chosen by using register 0x31 bit 4, INTN1
or INTN2.
Table 13. Interrupt Overview
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8.2 ENABLING AND CLEARING INTERRUPTS
The interrupt status register (0x14) contains the bits for the sample acquisition interrupt
ACQ_INT and the motion interrupts. The FIFO interrupt status register (0x2F) contains the bits
for the FIFO interrupts The interrupt enable register (0x06) and FIFO control register (0x2D)
determine if a flag event generates interrupts.
The interrupts are cleared and rearmed every time the interrupt status register (0x14) is
written. Interrupts may be cleared globally or individually.
When an event is detected, it is masked with a flag bit in the interrupt enable register, and then
the corresponding status bit is set in the status registers.
The polarity and driving mode of the external interrupt signals may be chosen by setting the
INTN1 or INTN2 IPP and IAH bits in the GPIO control register (0x33).
8.3 INTERRUPT SOURCES
8.3.1 ACQ_INT INTERRUPT
The ACQ_INT flag bit in the status registers is always active. This bit is cleared when it is read.
When a sample has been produced, an interrupt will be generated only if the ACQ_INT_EN bit
in the interrupt enable register is active. The frequency of the ACQ_INT bit being set active is
always the same as the sample rate.
8.3.2 TILT/FLIP (TILT_INT, FLIP_INT)
The TILT and FLIP flag bits in register 0x03/0x13 bit are active when the TILT/FLIP features
are enabled by register 0x9 bit 0. The flag bits can transition quickly, so polled operation may
be difficult. It is recommended to use the interrupt register 0x14 bits 0 or 1 instead. Note that
the TILT and FLIP interrupt enables in register 0x06 bits [1:0] are separate, although there is a
single control bit in register 0x09.
8.3.3 INTERRUPT ON ANYMOTION (ANYM_INT)
The ANYM flag bit in register 0x03/0x13 bit is active when the ANYM feature is enabled by
register 0x9 bit 2. The flag bit can transition quickly, so polled operation may be difficult. It is
recommended to use the interrupt in register 0x14 bit 2 instead. Note that the SHAKE and
TILT_35 interrupts require the ANYM feature to be enabled in register 0x09 bit 2, but the
ANYM interrupt enable in register 0x06 bit 2 is not required.
8.3.4 INTERRUPT ON SHAKE (SHAKE_INT)
The SHAKE flag bit in register 0x03/0x13 bit is active when the SHAKE feature is enabled by
register 0x9 bit 3. The flag bit can transition quickly, so polled operation may be difficult. It is
recommended to use the interrupt register 0x14 bit 3 instead. Note that the SHAKE interrupt
requires the ANYM feature to be enabled in register 0x09 bit 2, but the ANYM interrupt enable
in register 0x06 bit 2 is not required.
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8.3.5 INTERRUPT ON TILT_35 (TILT_35_INT)
The TILT_35 flag bit in register 0x03/0x13 bit is active when the SHAKE feature is enabled by
register 0x9 bit 4. The flag bit can transition quickly, so polled operation may be difficult. It is
recommended to use the interrupt register 0x14 bit 4 instead. Note that the TILT_35 interrupt
requires the ANYM feature to be enabled in register 0x09 bit 2, but the ANYM interrupt enable
in register 0x06 bit 2 is not required.
8.3.6 INTERRUPT ON FIFO EMPTY (FIFO_EMPTY_INT)
The FIFO_EMPTY flag bit in register 0x0A bit 0 is active when the FIFO enable (FIFO_EN)
control is enabled in register 0x2D bit 5. The FIFO_EMPTY flag will be set to ‘1’ following a
POR or SW_RESET because the default state of the FIFO is empty. Note that the
FIFO_EMPTY bit may transition on any write or read to the FIFO. The FIFO_EMPTY_INT_EN
interrupt control bit is at register 0x2D bit 0. No bits in register 0x06 are required to be set.
8.3.7 INTERRUPT ON FIFO FULL (FIFO_FULL_INT)
The FIFO_FULL flag bit in register 0x0A bit 1 is active when the FIFO enable (FIFO_EN)
control is enabled in register 0x2D bit 5. The FIFO_FULL flag will be set to ‘0’ following a POR
or SW_RESET because the default state of the FIFO is empty. Note that the FIFO_FULL bit
may transition on any write or read to the FIFO. The FIFO_FULL_INT_EN interrupt control bit
is at register 0x2D bit 1. No bits in register 0x06 are required to be set.
8.3.8 INTERRUPT ON FIFO THRESHOLD (FIFO_THRESH_INT)
The FIFO_THRESH flag bit in register 0x0A bit 2 is active when the FIFO enable (FIFO_EN)
control is enabled in register 0x2D bit 5. The FIFO_THRESH flag will be set to ‘0’ following a
POR or SW_RESET because the default state of the FIFO is empty, and the default threshold
level is a count of 16 samples (located in register 0x2E). Note that the FIFO_THRESH bit may
transition on any write or read to the FIFO when a threshold level is crossed. The
FIFO_THERESH_INT_EN interrupt control bit is at register 0x2D bit 2. No bits in register 0x06
are required to be set.
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8.4 INTERRUPT SERVICING
The MC3479 offers two methods for software to clear interrupts, and three operational modes.
Methods:
•
•
Global Method: Software may globally clear all pending interrupts.
Bitmask/Individual Method: Software may individually clear specific interrupts.
Modes:
•
•
•
Mode 1 Latched: software clears any/all pending interrupts.
Mode 2 Temp Latched: software clears interrupts or the temp_latch timer feature in
register 0x4A clears interrupts on a selected time out period.
Mode 3 Auto-Clear: software clears interrupts or hardware auto-clears interrupts.
Note that some interrupts are not supported in Modes 2 or 3. Please contact MEMSIC for more
information.
8.4.1 GLOBAL INTERRUPT SERVICE METHOD
Global mode (register 0x31 bit 6 = 0) is the default means for servicing interrupts. In this mode
any write to registers 0x04 or 0x14 will clear *any* pending interrupts, including the FIFO
interrupts in register 0x2F. The contents of the write cycle to registers 0x04/0x14 is ignored,
but the address is used to generate the clear pulse. The table below shows how the interrupt
sources behave in the three modes of interrupt operations. Note that the FIFO interrupts
only operate in Mode 1.
8.4.2 BITMASK/INDIVIDUAL INTERRUPT SERVICE MODE
Bitmask/individual mode is enabled by setting register 0x31 bit 6 to ‘1’. In this mode, register
0x04 is not used to clear interrupts, only register 0x14. The contents of the write cycle to
register 0x14 determine which interrupts are cleared (0 = no change, 1 = clear). Writing to
register 0x14 bit 5 clears all pending FIFO interrupt flags in 0x2F (e.g. the single FIFO_INTR
bit at register 0x14 bit 5 is a combined FIFO interrupt clear). The table below shows how the
interrupt sources behave in the three modes of interrupt operations. Note that the FIFO
interrupts only operate in Mode 1.
Mode of
Operation
Mode 1
Latched
Mode 2
Temp Latch
ACQ_INT
TILT_35_INT
SHAKE_INT
ANYM_INT
FLIP_INT
TILT_INT
Set
End of Z-axis
processing
TILT_35 condition
has exceeded
TILT_35 duration
(1.6 to 3.0s).
ANYM enable
required.
SHAKE_INT peak
threshold and
duration have
been met. ANYM
enable required.
ANYM lock status
met and relative
threshold
exceeded.
TF threshold
exceeded and
debounce count
met for TILT to
FLIP transitions.
TF threshold
exceeded and
debounce count
met for FLAT to
TILT or FLIP to TILT
transitions.
Clear
Write to 0x14
Write to 0x14
Write to 0x14
Write to 0x14
Write to 0x14
Write to 0x14
Set
End of Z-axis
processing
TILT_35 condition
has exceeded
TILT_35 duration
(1.6 to 3.0s).
SHAKE_INT peak
threshold and
duration have
ANYM lock status
met and relative
threshold
exceeded.
TF threshold
exceeded and
debounce count
TF threshold
exceeded and
debounce count
met for FLAT to
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Mode 3
Auto-Clear
ANYM enable
required.
been met. ANYM
enable required.
met for TILT to
FLIP transitions.
TILT or FLIP to TILT
transitions.
Clear
Temp latch period
timeout or write to
0x14
Temp latch period
timeout or write to
0x14
Temp latch period
timeout or write to
0x14
Temp latch period
timeout or write to
0x14
Temp latch period
timeout or write to
0x14
Temp latch period
timeout or write to
0x14
Set
End of Z-axis
processing
TILT_35 condition
has exceeded
TILT_35 duration
(1.6 to 3.0s).
ANYM enable
required.
SHAKE_INT peak
threshold and
duration have
been met. ANYM
enable required.
ANYM lock status
met and relative
threshold
exceeded.
TF threshold
exceeded and
debounce count
met for TILT to
FLIP transitions.
TF threshold
exceeded and
debounce count
met for FLAT to
TILT or FLIP to TILT
transitions.
Clear
Beginning of Z-axis
accumulation, or
write to 0x14
Cleared when
condition ends or
is reset by
hardware, or write
to 0x14
Cleared when
condition ends or
is reset by
hardware, or write
to 0x14
Cleared when
condition ends or
is reset by
hardware, or write
to 0x14
Cleared when
condition ends or
is reset by
hardware, or write
to 0x14
Cleared when
condition ends or
is reset by
hardware, or write
to 0x14
Table 14. Interrupt servicing details (Motion + Sample)
Mode of Operation
Mode 1
Latched
FIFO_THRESH
FIFO_FULL
FIFO_EMPTY
Set
FIFO sample count equals or
exceeds the FIFO threshold
count in register 0x2E.
FIFO has 32 samples; hardware
writes to the FIFO in WAKE mode
and FIFO_EN = 1.
FIFO has 0 samples. Reading
the FIFO at register 0xD with
I2C/SPI removes 1 or more
samples.
Clear
Write to 0x14
Write to 0x14
Write to 0x14
Table 15. Interrupt servicing details (FIFO)
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8.5 INTERRUPT REQUESTS AND EXTERNAL INT PINS
MC3479 has two pins which support external interrupts. Each pin may be separately
configured as open-drain or active drive and the polarity is programmable. Note that the drive
and polarity control has been moved from register 0x07 to register 0x33.
By default the sample + motion interrupt request is routed to the INTN1 pin, and FIFO interrupt
request is routed to the INTN2 pin. These requests may be swapped between the INTN1 pin
and INTN2 pin or combined on a single pin.
8.5.1 SELECTING DRIVE AND POLARITY
The drive mode (open-drain or push/pull) are controlled by register 0x33 bits 7:6 and 3:2.
Addr
Name
0x33 GPIO_CTRL
Descriptio
n
GPIO
Control
Register
Bit
7
6
5
4
3
2
1
0
GPIO2_
INTN2_IPP
GPIO2_
INTN2_
IAH
Resv
Resv
GPIO1_
INTN1_IPP
GPIO1_
INTN1_
IAH
Resv
Resv
POR Value
R/W
0x00
RW
Table 16. GPIO Control Register
Bit
2
Name
Function
Description
GPIO1_INTN1_IAH
Set polarity of INTN1 output.
0: The INTN1 pin is active low.
1: The INTN1 pin is active high.
This bit sets the polarity level of the INTN1 pin. This bit is used in
interrupt mode to set the level of the interrupt request.
3
GPIO1_INTN1_IPP
Select open drain or push/pull mode for INTN1.
0: The INTN1 pin operates in open-drain mode as an output and
requires an external pullup to VDD.
1: The INTN1 pin operates in push-pull mode as an output.
This bit sets the drive mode of the INTN1 pin as an interrupt
request output.
6
GPIO2_INTN2_IAH
Set polarity of INTN2 output.
0: The INTN2 pin is active low.
1: The INTN2 pin is active high.
This bit sets the polarity level of the INTN2 pin. This bit is used in
interrupt mode to set the level of the interrupt request.
7
GPIO2_INTN2_IPP
Select open drain or push/pull mode for INTN2.
0: The INTN2 pin operates in open-drain mode as an output and
requires an external pullup to VDD.
1: The INTN2 pin operates in push-pull mode as an output.
This bit sets the drive mode of the INTN2 pin as an interrupt
request output.
Table 17. Interrupt drive and polarity control
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8.5.2 SWAPPING INT PINS
The interrupt requests driving the INTN1 and INTN2 pins may be swapped. Setting register
0x31 bit 4 to ‘1’ (INT1_INT2_REQ_SWAP) internally swaps the INT1_REQ and INT2_REQ signals in the
MC3479. To clarify, the requests are swapped, but the bits controlling the INTN1 and INTN2 pin mode,
drive, and polarity are not.
Bit
Name
Function
Description
4
INT1_INT2_REQ_SWAP
Swap INT1 and INT2 pin
functionality.
0: INT1 requests are routed to the INTN1 pin, INTN2 requests are routed to the
INT2 pin (default).
1: INT1 requests are routed to the INTN2 pin, INT2 requests are routed to the
INTN1 pin
Table 18. Swapping Interrupt Requests, register 0x31 bit 4
8.5.3 COMBINING INTERRUPT REQUESTS
The separate internal interrupt requests (INT1_REQ or motion + sample, and INT2_REQ or
FIFO) may be combined into a single request that appears on one pin. Setting register 0x2D
bit 3 (COMB_INT_EN) to ‘1’ combines both requests on INT1_REQ that is routed to the INTN1
pin. To move it to the INTN2 pin, use the pin “swap” feature described in the previous section.
Bit Name
3
COMB_INT_EN
Function
Description
Combined interrupt
enable.
0: Motion/interrupt on sample interrupts are routed to
INTN1, and FIFO interrupts are routed to INTN2.
(default).
1: All interrupts are routed to INTN1.
When the COMB_INT_EN bit is set, all interrupts
requests are routed to INT1_REQ internally. INT2_REQ
becomes disabled.
Table 19. Combining interrupt requests, register 0x2D bit 3
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9 SAMPLING
9.1 CONTINUOUS SAMPLING
The device has the ability to read all sampled readings in a continuous sampling fashion. The
device always updates the XOUT, YOUT, and ZOUT registers at the chosen output data rate.
An optional interrupt can be generated each time the sample registers have been updated
(using the ACQ_INT bit in the interrupt enable register). See the ACQ_INT Interrupt section
or status register for more information about ACQ_INT.
9.2 SETTING THE SAMPLE RATE
The MC3419 supports eight sample rates using I2C or SPI interfaces. When decimation mode
is disabled, the table below shows the “internal data rate” (IDR) which is the same as ODR
(ODR = IDR). The sample rate register (0x08) selects the WAKE mode sample rate.
If the I2C interface is selected or if the SPI clock frequency is 4 MHz or less, use the register
0x08 settings as shown in the “Selection A” column below. If the SPI clock frequency is 4 MHz
to 10 MHz, use the register 0x08 settings as shown in the “Selection B” column below.
I2C & SPI interface
Rate
IDR = ODR (Hz)
Reg 0x08
0
50
0x08
1
100
0x09
2
125
0x0A
3
200
0x0B
4
250
0x0C
5
500
0x0D
6
1000
0x0E
7
2000
0x0F
Table 20. Sample Rate Settings
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9.3 ADDITIONAL RATE OPTIONS
The MC3479 is able to generate slower sample rates from the frequencies listed in The
MC3419 supports eight sample rates using I2C or SPI interfaces. When decimation mode is
disabled, the table below shows the “internal data rate” (IDR) which is the same as ODR (ODR
= IDR). The sample rate register (0x08) selects the WAKE mode sample rate.
If the I2C interface is selected or if the SPI clock frequency is 4 MHz or less, use the register
0x08 settings as shown in the “Selection A” column below. If the SPI clock frequency is 4 MHz
to 10 MHz, use the register 0x08 settings as shown in the “Selection B” column below.
I2C & SPI interface
Rate
IDR = ODR (Hz)
Reg 0x08
0
50
0x08
1
100
0x09
2
125
0x0A
3
200
0x0B
4
250
0x0C
5
500
0x0D
6
1000
0x0E
7
2000
0x0F
Table 20. When decimation mode is enabled the “internal data rate” (IDR) is divided by a fixed
ratio to obtain an ODR or “output data rate”. If decimation mode is not enabled (default), the
IDR and ODR are the same frequency. The FIFO control 2/sample rate 2 register (0x30)
selects the ratio used for decimation mode.
Bits
Name
Function
Description
3:0
DEC_MODE_
RATE[3:0]
Decimation mode rate
selection.
0000: Decimation mode disabled (default).
0001: Divide sample rate by 2
0010: Divide sample rate by 4
0011: Divide sample rate by 5
0100: Divide sample rate by 8
0101: Divide sample rate by 10
0110: Divide sample rate by 16
0111: Divide sample rate by 20
1000: Divide sample rate by 40
1001: Divide sample rate by 67
1010: Divide sample rate by 80
1011: Divide sample rate by 100
1100: Divide sample rate by 200
1101: Divide sample rate by 250
1110: Divide sample rate by 500
1111: Divide sample rate by 1000
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When decimation mode is enabled, the internal data rate (IDR) is divided by
the above factor to create a slower output data rate (ODR). The FIFO, motion
block, output registers, and interrupts operate off the slower ODR when
decimation mode is on.
If decimation mode is disabled, then the IDR and ODR are the same value.
Table 21. Hardware Decimation Ratios
The FIFO, motion events, and interrupts operate at the decimated rate (output data rate) when
decimation mode is enabled. The low pass filter always operates at the internal data rate
whether decimation mode is on or off.
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10
I2C INTERFACE
10.1 PHYSICAL INTERFACE
The I2C slave interface operates at a maximum speed of 1 MHz. The SDA (data) is an opendrain, bi-directional pin and the SCL (clock) is an input pin.
Note: The device always operates as an I2C slave.
An I2C master initiates all communication and data transfers and generates the SCL clock that
synchronizes the data transfer. The I2C device address depends upon the state of the
DOUT_A6 pin during power-up as shown in the table below.
An optional I2C watchdog timer can be enabled to prevent bus stall conditions. See the
Watchdog Timer section for more information.
7-bit Device ID
8-bit Address – Write
8-bit Address – Read
DOUT_A6 level upon
power-up
0x4C
(0b1001100)
0x98
0x99
GND
0x6C
(0b1101100)
0xD8
0xD9
VDD
Table 22. I2C Address Selection
The I2C interface remains active as long as power is applied to the VDD pin. In the STANDBY
state, the device responds to I2C read and write cycles, but interrupts cannot be serviced or
cleared. All registers can be written in the STANDBY state, but in the WAKE state, only the
mode register can be modified (see the Operational States section for more information).
Internally, the registers which are used to store samples are clocked by the sample clock gated
by I2C activity. Therefore, in order to allow the device to collect and present samples in the
sample registers, at least one I2C STOP condition must be present between samples.
Refer to the I2C specification for a detailed discussion of the protocol. Per I2C requirements,
SDA is an open drain, bi-directional pin. SCL and SDA each require an external pull-up
resistor, typically 4.7kΩ.
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10.2 TIMING
See the I2C Timing Characteristics section for I2C timing requirements.
10.3 I2C MESSAGE FORMAT
Note: At least one I2C STOP condition must be present between samples in order for the
sensor to update the sample data registers.
The device uses the following general format for writing to the internal registers: The I2C
master generates a START condition and then supplies the 7-bit device ID. The 8th bit is the
R/W# flag (write cycle = 0). The device pulls SDA low during the 9 th clock cycle indicating a
positive ACK.
The second byte is the 8-bit register address of the device to access. The last byte is the data
to write.
START
I2C Master
(To Sensor)
S
Device ID
1
1
0
1
R/W#
1
1
0
I2C Slave
(From Sensor)
Register Address
0
R7
R6
R5
R4
R3
R2
Register Data to Write
R1
R0
D7
D6
D5
D4
D4
D2
D1
Stop
D0
P
ACK
ACK
ACK
ACK/NAK
ACK/NAK
ACK/NAK
Figure 13. I2C Message Format, Write Cycle, Single Register Write
In a read cycle, the I2C master generates a START condition and then writes the device ID,
R/W# flag (write cycle = 0), and register address. The master issues a RESTART condition
and then writes the device ID with the R/W# flag set to ‘1’. The device shifts out the contents of
the register address.
START
I2C Master
(To Sensor)
I2C Slave
(from Sensor)
S
Device ID
1
1
0
1
1
R/W#
1
0
Register Address
0
R7
R6
R5
R4
R3
R2
Restart
R1
R0
R
Device ID
1
1
0
1
1
R/W#
1
0
NAK
NAK
1
ACK
ACK
ACK
ACK/NAK
ACK/NAK
ACK/NAK
D7
D6
D5
D4
D3
D2
D1
STOP
P
D0
Read Data Byte
Figure 14. I2C Message Format, Read Cycle, Single Register Read
The I2C master may write or read consecutive register addresses by writing or reading
additional bytes after the first access. The device will internally increment the register address.
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10.4 I2C WATCHDOG TIMER
The I2C watchdog timer, when enabled (see the mode register), prevents bus stall conditions
when the master does not provide enough clocks to the slave to complete a read cycle. The
I2C watchdog timer does not resolve why the master did not provide enough clocks to
complete a read cycle, but it does prevent a slave from holding the bus indefinitely.
During a read cycle, the slave that is actively driving the bus (SDA pin) does not release the
bus until nine SCL clock edges are detected. While the SDA pin is held low by a slave opendrain output, any other I2C devices attached to the bus will not be able to communicate. If the
slave does not see nine SCL clocks from the master within the timeout period (about 200 ms),
the slave assumes a system problem has occurred and resets the I2C circuitry, releases the
SDA pin, and readies the sensor for additional I2C commands.
When an I2C watchdog timer event is triggered, the I2C_WDT bit in the device status
register is activated by the Watchdog timer hardware. No other registers are changed.
External software can detect this activation by reading the I2C_WDT bit. Reading the device
status register (0x05) clears the I2C_WDT bit.
MEMSIC MC3479 APS-048-0072 v1.12
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11
SPI INTERFACE
11.1 SPI PHYSICAL INTERFACE
The device always operates as an SPI slave. An SPI master must initiate all communication
and data transfers and generate the SCK_SCL clock that synchronizes the data transfer. The
CSN pin must be pulled up to VDD when the SPI interface is not in use. The SPI interface can
operate in 3-wire or 4-wire mode. See section 9.2 for SPI clock selection and Output Data
Rate, ODR.
11.2 SPI PROTOCOL
An SPI write transaction requires a minimum of 16 clock cycles, and a SPI read
transaction requires a minimum of 24 cycles of the SCK_SCL pin. The falling edge of
CSN initiates the start of the SPI bus cycle. When the SPI master is writing data to the
MC3419 via the SPI DIN pin, data may change when the SCL_SCK is low, and must be stable
on the rising edge. Similarly, output data written from MC3419 to the SPI master is shifted out
on the SPI DOUT pin on the falling edge of SCL_SCK and can be latched by the master on the
rising edge of SCL_SCK. Serial data in or out of the device is always MSB first.
11.3 SPI REGISTER WRITE CYCLE - SINGLE
A single register write consists of a 16-clock transaction. As described above, the first bit is set
to ‘0’ indicating a register write followed by the register address.
CSN
SCL_SCK
SPI_DIN
1
2
3
4
5
6
7
8
0
A6
A5
A4
A3
A2
A1
A0
9
10
DIN7 DIN6
11
12
DIN5
DIN4
13
14
DIN3 DIN2
15
16
DIN1
DIN0
Z
SPI_DOUT
Figure 15. SPI Register Write Cycle - Single
11.4 SPI REGISTER WRITE CYCLE - BURST
A burst (multi-byte) register write cycle uses the address specified at the beginning of the
transaction as the starting register address. Internally the address will auto-increment to the
next consecutive address for each additional byte (8-clocks) of data written beyond clock 8.
MEMSIC MC3479 APS-048-0072 v1.12
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CSN
SCL_SCK
DIN_SDA
1
2
3
4
5
6
7
8
0
A6
A5
A4
A3
A2
A1
A0
9
11
10
12
13
14
15
16
DIN7 DIN6 DIN5 DIN4 DIN3 DIN2 DIN1 DIN0
17
18
19
20
21
22
23
24
25
26
DIN15
DIN14
DIN13
DIN12
DIN11
DIN10
DIN9
DIN8
DIN31
DIN30
Data for register N
27
28
29
30
31
32
DIN29
DIN28
DIN27
DIN26
DIN25
DIN24
Data for register N+2
Data for register N+1
DOUT_A6
Figure 16.SPI Register Write Cycle - Burst (3-register burst example)
11.5 SPI REGISTER READ CYCLE - SINGLE
A single register read consists of a 24-clock transaction. As described above, the first bit is set
to ‘1’ indicating a register read followed by the register address.
CSN
SCL_SCK
DIN_SDA
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1
A6
A5
A4
A3
A2
A1
A0
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
DO7
DO6
DO5
DO4
DO3
DO2
DO1
DO0
DOUT_A6
Figure 17. SPI Register Read Cycle - Single
11.6 SPI REGISTER READ CYCLE - BURST
A burst (multi-byte) register read cycle uses the address specified at the beginning of the
transaction as the starting register address. Internally the address will auto-increment to the
next consecutive address for each additional byte (8-clocks) of data read beyond clock 8.
CSN
SCL_SCK
DIN_SDA
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
1
A6
A5
A4
A3
A2
A1
A0
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
DO7
DO6
DO5
DO4
DO3
DO2
DO1
DO0 DO15 DO14 DO13 DO12 DO11 DO10 DO9
DO8
DOUT_A6
Data read from register N
Data read from register N+1
Figure 18. SPI Register Read Cycle - Burst (2 register burst example)
MEMSIC MC3479 APS-048-0072 v1.12
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11.7 TIMING
Figure 19. SPI Interface Timing
Table 23. SPI Timing Characteristics
MEMSIC MC3479 APS-048-0072 v1.12
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12
REGISTER INTERFACE
The device has a register interface which allows an MCU, I2C or SPI master to configure and
monitor all aspects of the device. This section lists an overview of user programmable
registers. By convention, bit 0 is the least significant bit (LSB) of a byte register.
12.1 REGISTER SUMMARY
NOTE: Registers are not updated with new event status or samples while an I2C or SPI cycle
is in process.
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 3
Bit 2
Bit 1
Bit 0
POR
Value
R/W1
STATE[0]
0x00
R
0x00
W
RESERVED2
0x00 – 0x04
0x05
DEV_STAT
Device Status
Register
0x06
INTR_
CTRL
Interrupt Enable
0x07
MODE
Mode
RESV
RESV
0x08
SR
Sample Rate
03
03
0x09
MOTION_
CTRL
Motion Control
0x0A
FIFO_
STAT
FIFO Status
Register
0x0B
Bit 4
FIFO-RD_P FIFO Read Pointer
OTP_BUSY
SEC_ENA
(TMODE)
ACQ_INT AUTO_
_EN
CLR_EN
RAW_
MOTION
PROC_
_RESET
STAT
RESV
I2C_WDT
RESV
TILT_35_ SHAKE_
INT_EN INT_EN
I2C_
I2C_
RESV
WDT_POS WDT_NEG
Resv
03
03
03
Z_AXIS_ TILT_35_ SHAKE_
ORT
EN
EN
RES_MODE STATE[1]
ANYM_ FLIP_INT_ TILT_INT_
INT_EN
EN
EN
03
STATE1
STATE0
0x00
W
RATE[2]
RATE[1]
RATE[0]
0x00
W
ANYM_ MOTION_
TF_
EN
LATCH ENABLE
0x00
W
FIFO_
FIFO_
FIFO_FULL
THRESH
EMPTY
0x00
RO
FIFO_
RD_PTR[2]
RESV
RESV
RESV
RESV
RESV
RESV
RESV
FIFO_
RD_PTR[5]
FIFO_
RD_PTR[4]
FIFO_
RD_PTR[3]
FIFO_
RD_PTR[0]
0x00
RO
RESV
RESV
FIFO_
FIFO_
FIFO_
FIFO_
FIFO_
FIFO_
WR_PTR[5] WR_PTR[4] WR_PTR[3] WR_PTR[2] WR_PTR[1] WR_PTR[0]
0x00
RO
FIFO_
RD_PTR[1]
FIFO_
WR_P
XOUT_
EX_L
XOUT Accelerometer XOUT_
Data LSB
EX[7]
XOUT_
EX[6]
XOUT_
EX[5]
XOUT_
EX[4]
XOUT_
EX[3]
XOUT_
EX[2]
XOUT_
EX[1]
XOUT_
EX[0]
0x00
R
0x0E
XOUT_
EX_H
XOUT Accelerometer XOUT_
Data MSB
EX[15]
XOUT_
EX[14]
XOUT_
EX[13]
XOUT_
EX[12]
XOUT_
EX[11]
XOUT_
EX[10]
XOUT_
EX[9]
XOUT_
EX[8]
0x00
R
0x0F
YOUT_
EX_L
YOUT Accelerometer YOUT_
Data LSB
EX[7]
YOUT_
EX[6]
YOUT_
EX[5]
YOUT_
EX[4]
YOUT_
EX[3]
YOUT_
EX[2]
YOUT_
EX[1]
YOUT_
EX[0]
0x00
R
0x10
YOUT_
EX_L
YOUT Accelerometer YOUT_
Data MSB
EX[15]
YOUT_
EX[14]
YOUT_
EX[13]
YOUT_
EX[12]
YOUT_
EX[11]
YOUT_
EX[10]
YOUT_
EX[9]
YOUT_
EX[8]
0x00
R
0x11
ZOUT_
EX_L
ZOUT Accelerometer ZOUT_
Data LSB
EX[7]
ZOUT_
EX[6]
ZOUT_
EX[5]
ZOUT_
EX[4]
ZOUT_
EX[3]
ZOUT_
EX[2]
ZOUT_
EX[1]
ZOUT_
EX[0]
0x00
R
0x12
ZOUT_
EX_H
ZOUT Accelerometer ZOUT_
Data MSB
EX[15]
ZOUT_
EX[14]
ZOUT_
EX[13]
ZOUT_
EX[12]
ZOUT_
EX[11]
ZOUT_
EX[10]
ZOUT_
EX[9]
ZOUT_
EX[8]
0x00
R
0x13
STATUS
TILT_
FLAG
0x00
R
0x00
R
0x0C
0x0D
INTR_
STAT
0x15 – 0x1F
0x14
FIFO Write Pointer
Status Register
NEW_
DATA
RESV
FIFO_FLAG
Interrupt Status
Register
ACQ_INT
RESV
FIFO_INT
0
1
0x18
Chip id
Chip Identification
Register
1
0x20
RANGE
Range Select Control
03
0x21
XOFFL
X-Offset
LSB
TILT_35_ SHAKE_
FLAG
FLAG
ANYM_
FLIP_FLAG
FLAG
TILT_35_ SHAKE_
INT
INT
RESERVED2
ANYM_
INT
0
0
RANGE[2] RANGE[1] RANGE[0] LPF_EN
XOFF[7] XOFF[6]
MEMSIC MC3479 APS-048-0072 v1.12
XOFF[5]
XOFF[4]
Page 41 of 80
XOFF[3]
FLIP_INT TILT_INT
1
0
0
0xA4
R
LPF[2]
LPF[1]
LPF[0]
0x00
W
XOFF[2]
XOFF[1]
XOFF[0] Per chip
W
2021/05
Bit 7
Bit 6
Bit 5
Description
0x22
XOFFH
X-Offset
MSB
XGAIN[8] XOFF[14] XOFF[13] XOFF[12] XOFF[11] XOFF[10] XOFF[9]
XOFF[8] Per chip
W
0x23
YOFFL
Y-Offset
LSB
YOFF[7] YOFF[6]
YOFF[1]
YOFF[0] Per chip
W
I0x24
YOFFH
Y-Offset
MSB
YGAIN[8] YOFF[14] YOFF[13] YOFF[12] YOFF[11] YOFF[10] YOFF[9]
YOFF[8] Per chip
W
0x25
ZOFFL
Z-Offset
LSB
ZOFF[7] ZOFF[6]
ZOFF[1]
ZOFF[0]
Per chip
W
0x26
ZOFFH
Z-Offset
MSB
ZGAIN[8] ZOFF[14] ZOFF[13] ZOFF[12] ZOFF[11] ZOFF[10] ZOFF[9]
ZOFF[8]
Per chip
W
0x27
XGAIN
X Gain
XGAIN[7] XGAIN[6] XGAIN[5] XGAIN[4] XGAIN[3] XGAIN[2] XGAIN[1] XGAIN[0] Per chip
W
0x28
YGAIN
Y Gain
YGAIN[7] YGAIN[6] YGAIN[5] YGAIN[4] YGAIN[3] YGAIN[2] YGAIN[1] YGAIN[0] Per chip
W
0x29
ZGAIN
Z Gain
ZGAIN[7] ZGAIN[6] ZGAIN[5] ZGAIN[4] ZGAIN[3] ZGAIN[2] ZGAIN[1] ZGAIN[0] Per chip
W
ZOFF[5]
0x2D
FIFO_
CTRL
FIFO Control Register
03
FIFO_
MODE
0x2E
FIFO_TH
FIFO Threshold
Register
RESV
RESV
RESV
0x2F
FIFO_
INTR
FIFO Interrupt Status
Register
03
RESV
RESV
0x30
FIFO_
CTRL2 _SR2
FIFO_
BURST_
MODE
03
SELECT_
WRAP_
ADDR
0x31
COMM_
CTRL
FIFO Control 2,
Sample Rate 2
Register
Comm. Control
Register
03
FIFO_EN FIFO_RESET
0x43
0x44
0x45
0x46
TF_DB
YOFF[2]
ZOFF[2]
Bit 1
Bit 0
FIFO_
COMB_INT FIFO_TH_ FIFO_FULL_
EMPTY_
_ EN
INT_EN
INT_EN
INT_EN
0x00
W
FIFO_TH[4] FIFO_TH[3] FIFO_TH[2] FIFO_TH[1] FIFO_TH[0]
0x10
W
FIFO_
FIFO_FULL_ FIFO_EMPT
THRESH_
INT (RO) Y _INT (RO)
INT (RO)
0x00
R
W
DEC_
DEC_MODE DEC_MODE
MODE
RATE[1]
RATE[0]
RATE[2]
0x00
W
RESV
RESV
ENABLE_ DEC_MODE
WRAP_N RATE[3]
03
03
RESV
RESV
0x00
W
INTN1_
IPP
INTN1_IAH
RESV
RESV
0x00
W
0x00
W
0x00
W
0x00
W
RESERVED2
GPIO
Control Register
0x34 -0x3F
TF_
Tilt/Flip Threshold
0x40 THRESH_L
LSB
SB
TF_
Tilt/Flip Threshold
0x41 THRESH_
MSB
MSB
0x42
ZOFF[3]
INDIV_ SPI_3WIRE INT1_INT2_
INTR_CLR
_ EN
REQ_SWAP
0x32
GPIO_
CTRL
ZOFF[4]
YOFF[3]
Bit 2
RESERVED2
0x2A -0x2C
0x33
YOFF[4]
Bit 3
R/W1
Name
YOFF[5]
Bit 4
POR
Value
Addr
INTN2_
INTN2_IAH
IPP
RESV
RESV
RESERVED2
TF_
TF_
TF_THR[6] TF_THR[5] TF_THR[4] TF_THR[3] TF_THR[2] TF_THR[1]
THR[7]
THR[0]
RESV
TF_
THR[14]
TF_
THR[13]
TF_
THR[12]
TF_
THR[11]
TF_
TF_
TF_THR[9]
THR[10]
THR[8]
Tilt/Flip Debounce TF_DB[7] TF_DB[6] TF_DB[5] TF_DB[4] TF_DB[3] TF_DB[2] TF_DB[1] TF_DB[0]
AM_
AnyMotion Threshold
THRESH_L
LSB
SB
AM_
AnyMotion Threshold
THRESH_
MSB
MSB
AnyMotion
AM_DB
Debounce
SHK_
THRESH_L Shake Threshold LSB
SB
ANYM_
THR[7]
ANYM_
THR[6]
ANYM_
THR[5]
ANYM_
THR[4]
ANYM_
THR[3]
ANYM_
THR[2]
ANYM_
THR[1]
ANYM_
THR[0]
0x00
W
RESV
ANYM_
THR[14]
ANYM_
THR[13]
ANYM_
THR[12]
ANYM_
THR[11]
ANYM_
THR[10]
ANYM_
THR[9]
ANYM_
THR[8]
0x00
W
ANYM_
DB[7]
ANYM_
DB[6]
ANYM_
DB[5]
ANYM_
DB[4]
ANYM_
DB[3]
ANYM_
DB[2]
ANYM_
DB[1]
ANYM_
DB[0]
0x00
W
SH _
THR[7]
SH _
THR[6]
SH _
THR[5]
SH _
THR[4]
SH _
THR[3]
SH _
THR[2]
SH _
THR[1]
SH _
THR[0]
0x00
W
MEMSIC MC3479 APS-048-0072 v1.12
Page 42 of 80
2021/05
Addr
0x47
0x48
0x49
0x4A
0x4B
Name
Description
Bit 7
Bit 6
Bit 5
SHK_
SH_
SH _
SH _
SH _
THRESH_ Shake Threshold MSB
THR[15] THR[14] THR[13] THR[12]
MSB
PK_P2P_D
UR_
Peak-to-Peak
PK_P2P_ PK_P2P_ PK_P2P_ PK_P2P_
THRESH_L
Duration LSB
DUR[7] DUR[6] DUR[5] DUR[4]
SB
PK_P2P_D
Shake Duration and
UR_
SHK_CNT_ SHK_CNT SHK_CNT_
RESV
Peak-to-Peak
THRESH_
DUR[2] _DUR[1] DUR[0]
Duration MSB
MSB
TEMP_
TIMER_CT
TEMP_ TEMP_ TEMP_
Timer Control
PER_INT
RL
PERIOD[2] PERIOD[1] PERIOD[0]
_EN
RD_CNT Read Count Register
Bit 3
Bit 2
Bit 1
Bit 0
POR
Value
R/W1
SH _
THR[11]
SH _
THR[10]
SH _
THR[9]
SH _
THR[8]
0x00
W
PK_P2P_ PK_P2P_ PK_P2P_ PK_P2P_
DUR[3] DUR[2] DUR[1] DUR[0]
0x00
W
PK_P2P_ PK_P2P_ PK_P2P_ PK_P2P_
DUR[11] DUR[10] DUR[9] DUR[8]
0x00
W
0x00
W
0x06
R/W
Bit 4
RESV
TILT_
35[2]
TILT_35[1]
TILT_
35[0]
RD_CNT[7] RD_CNT[6] RD_CNT[5] RD_CNT[4] RD_CNT[3] RD_CNT[2] RD_CNT[1] RD_CNT[0]
0x4C – 0x50
RESERVED2
1
‘R’ registers are read-only, via external I2C access. ‘W’ registers are read-write, via external I2C access.
Registers designated as ‘RESERVED’ should not be accessed by software.
3 Software must write a zero (0) to this bit.
4 Software must write a one (1) to this bit.
2
Table 24. Register Summary
MEMSIC MC3479 APS-048-0072 v1.12
Page 43 of 80
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12.2 (0X05)DEVICE STATUS REGISTER
The device status register reports various conditions of the sensor circuitry.
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
0x05
DEV_
STAT
Device Status
OTP_
BUSY
Resv
Resv
I2C_WDT
Resv
RES_
MODE
Name
STATE[1:0]
RES_MODE
I2C_WDT
OTP_BUSY
Bit 1
Bit 0
STATE[1] STATE[0]
POR
Value
R/W
0x00
R
Description
Operating mode of the current device.
00: STANDBY. Clocks are not running and X, Y, and Z-axis data are not
sampled.
01: WAKE. Clocks are running and X, Y, and Z-axis data are acquired at the
sample rate.
10: Reserved.
11: Reserved.
Resolution mode of the current device.
0: 16-bit (high) resolution is enabled.
1: Reserved.
I2C watchdog timeout. This bit is cleared when register 0x05 is read.
0: A watchdog event is not detected.
1: A watchdog event has been detected by the hardware and the I2C slave
state machine is reset to idle.
One-Time programming (OTP) activity status.
0: Internal memory is idle and the device is ready to use.
1: Internal memory is active and the device cannot be used.
Table 25. Device Status Register
MEMSIC MC3479 APS-048-0072 v1.12
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12.3 (0X06) INTERRUPT ENABLE REGISTER
The interrupt enable register enables or disables the reporting of interrupt status for each
interrupt source. FIFO interrupt are enabled in the FIFO control register 0x2D.
Addr
Name
Description
0x06
INTR_
CTRL
Interrupt Enable
Name
TILT_INT_EN
FLIP_INT_EN
ANYM_INT_EN
SHAKE_INT_EN
TILT_35_INT_EN
AUTO_CLR_EN
ACQ_INT_EN
Bit 7
Bit 6
ACQ_INT_ AUTO_
EN
CLR_EN
Bit 5
Resv
Bit 4
Bit 3
TILT_35_ SHAKE_
INT_EN INT_EN
Bit 2
Bit 1
Bit 0
ANYM_ FLIP_INT_ TILT_INT_
INT_EN
EN
EN
POR
Value
R/W
0x00
W
Description
Use with the tilt/flip feature in the motion control register (register 0x09, bit 0) to
activate the reporting status of the tilt interrupt.
0: Tilt interrupt is disabled.
1: Tilt interrupt is enabled.
Use with the tilt/flip feature in the motion control register (register 0x09, bit 0) to
activate the reporting status of the flip interrupt.
0: Flip interrupt is disabled.
1: Flip interrupt is enabled.
Use with the AnyMotion feature in the motion control register (register 0x09, bit
2) to activate the reporting status of the AnyMotion interrupt.
0: AnyMotion interrupt is disabled.
1: AnyMotion interrupt is enabled.
Use with the shake feature in the motion control register (register 0x09, bit 3)
and the AnyMotion feature in the motion control register (register 0x09, bit 2) to
activate the reporting status of the shake interrupt.
0: Shake interrupt is disabled.
1: Shake interrupt is enabled.
Use with the tilt-35 feature in the motion control register (register 0x09, bit 4)
and the AnyMotion feature in the motion control register (register 0x09, bit 2) to
activate the reporting status of the tilt-35 interrupt.
0: Tilt-35 interrupt is disabled.
1: Tilt-35 interrupt is enabled.
Clear pending interrupts automatically or by reading a register. Enabling more
than one interrupt timeout or service feature may produce unexpected results.
0: Clear pending interrupts by writing to register 0x14.
1: Automatically clear pending interrupts if the interrupt condition is no longer
valid. Refer to Interrupts for more information about interrupts.
Generate interrupts.
0: Disable automatic interrupt after each sample (default).
1: Enable automatic interrupt after each sample (activates the ACQ_INT flag,
bit 7, in register 0x14).
Table 26. Interrupt Enable Register
MEMSIC MC3479 APS-048-0072 v1.12
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12.4 (0X07) MODE REGISTER
The mode register controls the active operating state of the accelerometer. This register can
be written from all operational states (WAKE, or STANDBY).
Addr
Name
Description
Bit 7
Bit 6
0x07
MODE
Mode
Resv
Resv
1Software
Bit 5
Bit 4
I2C_
I2C_
WDT_POS WDT_NEG
Bit 3
Bit 2
0
01
Bit 1
Bit 0
STATE[1] STATE[0]
POR
R/W
Value
0x00
W
must write a zero (0) to bit 2.
Name
STATE[1:0]
I2C_WDT_NEG
I2C_WDT_POS
Description
Accelerometer operational state.
00: SLEEP. Clocks are not running and X, Y, and Z-axis data are not sampled.
01: WAKE. Clocks are running and X, Y, and Z-axis data are acquired at the
sample rate.
10: Reserved.
11: STANDBY. Clocks are running but X, Y, and Z-axis data are not sampled
Watchdog timer for negative SCL stalls.
0: The I2C watchdog timer for negative SCL stalls is disabled (default).
1: The I2C watchdog timer for negative SCL stalls is enabled.
Watchdog timer for positive SCL stalls.
0: The I2C watchdog timer for positive SCL stalls is disabled (default).
1: The I2C watchdog timer for positive SCL stalls is enabled.
Table 27. Mode Register States
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12.5 (0X08) SAMPLE RATE REGISTER
The sample rate register sets the sampling output data rate (ODR) for the sensor and the clock
frequency of the main oscillator.
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x08
SR
Sample Rate
01
01
01
01
12
RATE[2]
RATE[1]
RATE[0]
POR
R/W
Value
0x00
RW
1
Software must write a zero (0).
2
Software must write a one (1).
Name
RATE[2:0]
Description
Select the Output Data Rate, ODR
Table 28. Sample Rate Register
I2C & SPI interface
Rate
IDR = ODR (Hz)
Reg 0x08
0
50
0x08
1
100
0x09
2
125
0x0A
3
200
0x0B
4
250
0x0C
5
500
0x0D
6
1000
0x0E
7
2000
0x0F
Table 29. Sample Rate Values
MEMSIC MC3479 APS-048-0072 v1.12
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12.6 (0X09) MOTION CONTROL REGISTER
The motion control register enables the flags and interrupts for motion detection features.
Addr
0x09
Name
Description
Bit 7
Bit 6
RAW_
MOTION_
MOTION_
Motion Control
PROC_
CTRL
RESET
STAT
Name
TF_ENABLE
MOTION_LATCH
ANYM_EN
SHAKE _EN
TILT_35 _EN
Z_AXIS_ORT
RAW_PROC_STAT
MOTION_RESET
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Z_AXIS_ TILT_35_ SHAKE_
MOTION_
TF_
ANYM_EN
ORT
EN
EN
LATCH ENABLE
POR
Value
R/W
0x00
W
Description
Enable or disable the tilt/flip feature. Used with the tilt/flip features in registers
0x13, 0x14, and 0x06.
0: Tilt/Flip feature is disabled (default).
1: Tilt/Flip feature is enabled.
If motion interrupts are used, this bit is generally not used.
0: Motion block does not latch outputs.
1: Motion block latches outputs.
Enable or disable the AnyMotion feature. Used with the AnyMotion feature in
registers 0x13, 0x14, and 0x06 and the shake and tilt-35 features in registers
0x14 and 0x06.
0: AnyMotion feature is disabled (default).
1: AnyMotion feature is enabled.
Enable or disable the shake feature. Used with the shake feature in registers
0x13, 0x14, and 0x06.
0: Shake feature is disabled (default).
1: Shake feature is enabled. ANYM_EN must also be enabled.
Enable or disable the tilt-35 feature. Used with tilt-35 feature in registers 0x13,
0x14, and 0x06.
0: Tilt-35 feature is disabled (default).
1: Tilt-35 feature is enabled. ANYM_EN must also be enabled.
Z-axis orientation.
0: Z-axis orientation is positive through the top of the package (default).
1: Z-axis orientation is positive through the bottom of the package.
Enable or disable filtering of motion data.
0: Motion flag bits are filtered by debounce and other settings (default).
1: Motion flag bits are real-time, raw data.
Motion block reset. This bit is not automatically cleared.
0: The motion block is not in reset (default).
1: The motion block is held in reset. The software must set this bit for the
reset to be cleared.
Table 30. Motion Control Register
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12.7 (0X0A) FIFO STATUS REGISTER
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
0x0A
FIFO_STAT
FIFO Status
RESV
RESV
RESV
RESV
RESV
Bit 2
Bit 1
Bit 0
FIFO_
FIFO_
FIFO_FULL
THRESH
EMPTY
POR
Value
R/W
0x01
RO
This register returns the current flags/status from the FIFO. These signals are not registered so
the bits may transition unexpectedly at any time. The FIFO interrupt enable bits in register
0x2D do not affect these flags. Note that the FIFO_EMPTY flag is ‘1’ at boot or POR.
Bit
Name
Description
0
FIFO_EMPTY
0: FIFO is not empty
1: FIFO is empty (default)
This flag is valid if the FIFO is enabled or disabled.
1
FIFO_FULL
0: FIFO is not full (default)
1: FIFO is full
This flag is valid if the FIFO is enabled or disabled.
2
FIFO_THRESH
0: FIFO threshold is less than threshold setting (default)
1: FIFO threshold is at or greater than threshold setting.
The default threshold level is 16 or ½ of the 32 sample FIFO
capacity.
7:3
RESV
Reserved, returns ‘00000’ when read.
Table 19: FIFO Status, 0x0A Register
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12.8 (0X0B) FIFO READ POINTER REGISTER
Addr
Name
Description
Bit 7
Bit 6
0x0B
FIFO_R_P
FIFO Read Pointer
RESV
RESV
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
FIFO_
FIFO_
FIFO_
FIFO_
FIFO_
FIFO_
RD_PTR[5] RD_PTR[4] RD_PTR[3] RD_PTR[2] RD_PTR[1] RD_PTR[0]
POR
Value
R/W
0x00
RO
READ POINTER
The FIFO read pointer is a 6-bit value that points to the current address of the read port on the
FIFO. The actual address is bits 4:0 since the FIFO is limited to 32 locations. Bit 5 is used as
“wrap” flag by hardware when comparing the read and write pointer.
Bit
Name
Description
4:0
FIFO_RD_PTR[4:0]
00000 – default
This is the current address the FIFO read pointer is accessing. The
valid range is 0 to 31.
5
FIFO_RD_PTR[5]
0 -default
This bit is used by hardware to manage the full/empty status of
the FIFO. This is not a physical address bit.
7:6
RESV
Reserved, returns ‘00’ when read.
Table 12-31: FIFO read pointer, register 0x0B
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12.9 (0X0C) FIFO WRITE POINTER REGISTER
Addr
0x0C
Name
Description
FIFO_W_P FIFO Write Pointer
Bit 7
Bit 6
RESV
RESV
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
FIFO_
FIFO_
FIFO_
FIFO_
FIFO_
FIFO_
WR_PTR[5] WR_PTR[4] WR_PTR[3] WR_PTR[2] WR_PTR[1] WR_PTR[0]
POR
Value
R/W
0x00
RO
The FIFO write pointer is a 6-bit value that points to the current address of the write port on the
FIFO. The actual address is bits 4:0 since the FIFO is limited to 32 locations. Bit 5 is used as
“wrap” flag by hardware when comparing the read and write pointers. This value will always
be updated when a new valid sample is acquired (Z-axis data must be successfully acquired).
Bit
Name
Description
4:0
FIFO_WR_PTR[4:0]
00000 – default
This is the current address the FIFO write pointer is accessing. The
valid range is 0 to 31.
5
FIFO_WR_PTR[5]
0 -default
This bit is used by hardware to manage the full/empty status of
the FIFO. This is not a physical address bit.
7:6
RESV
Reserved, returns ‘00’ when read.
Table 12-32: FIFO write pointer, register 0xC
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12.10 (0X0D - 0X12) XOUT, YOUT AND ZOUT DATA ACCELEROMETER
REGISTERS
X, Y, and Z-axis accelerometer measurements are in 16-bit, signed 2’s complement format.
Register addresses 0x0D to 0x12 hold the latest sampled data from the X, Y, and Z
accelerometers.
When the FIFO is enabled (register 0x2D bit 5), reading from address 0x0D supplies data from
the FIFO instead of the output registers.
During FIFO reads, software must start a read at address 0x0D and complete a read to
address 0x12 for the FIFO pointers to increment correctly.
Once an I2C start bit has been recognized by the device, registers will not be updated until an
I2C stop bit has occurred. Therefore, if software desires to read the low and high byte registers
‘atomically’, knowing that the values have not been changed, it should do so by issuing a start
bit, reading one register, then reading the other register then issuing a stop bit. Note that all 6
registers may be read in one burst with the same effect.
Addr
Name
0x0D
XOUT_
EX_L
0x0E
XOUT_
EX_H
0x0F
YOUT_
EX_L
0x10
YOUT_
EX_L
0x11
ZOUT_
EX_L
0x12
ZOUT_
EX_H
Description
XOUT
Accelerometer
Data LSB
XOUT
Accelerometer
Data MSB
YOUT
Accelerometer
Data LSB
YOUT
Accelerometer
Data MSB
ZOUT
Accelerometer
Data LSB
ZOUT
Accelerometer
Data MSB
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
POR
Value
R/W
XOUT_
EX[7]
XOUT_
EX[6]
XOUT_
EX[5]
XOUT_
EX[4]
XOUT_
EX[3]
XOUT_
EX[2]
XOUT_
EX[1]
XOUT_
EX[0]
0x00
R
XOUT_
EX[15]
XOUT_
EX[14]
XOUT_
EX[13]
XOUT_
EX[12]
XOUT_
EX[11]
XOUT_
EX[10]
XOUT_
EX[9]
XOUT_
EX[8]
0x00
R
YOUT_
EX[7]
YOUT_
EX[6]
YOUT_
EX[5]
YOUT_
EX[4]
YOUT_
EX[3]
YOUT_
EX[2]
YOUT_
EX[1]
YOUT_
EX[0]
0x00
R
YOUT_
EX[14]
YOUT_
EX[13]
YOUT_
EX[12]
YOUT_
EX[11]
YOUT_
EX[10]
YOUT_
EX[9]
YOUT_
EX[8]
0x00
R
ZOUT_
EX[6]
ZOUT_
EX[5]
ZOUT_
EX[4]
ZOUT_
EX[3]
ZOUT_
EX[2]
ZOUT_
EX[1]
ZOUT_
EX[0]
0x00
R
ZOUT_
EX[14]
ZOUT_
EX[13]
ZOUT_
EX[12]
ZOUT_
EX[11]
ZOUT_
EX[10]
ZOUT_
EX[9]
ZOUT_
EX[8]
0x00
R
YOUT_
EX[15]
ZOUT_
EX[7]
ZOUT_
EX[15]
Table 33. Accelerometer LSB and MSB Registers
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12.11 (0X13) STATUS REGISTER
The status register contains the flag and status bits for sample acquisition and motion
detection.
Addr
Name
Description
Bit 7
Bit 6
0x13
STATUS
Status Register
NEW_
DATA
Resv
Name
TILT_FLAG
FLIP_FLAG
ANYM_FLAG
SHAKE_FLAG
TILT_35_FLAG
FIFO_FLAG
NEW_DATA
Bit 5
Bit 4
FIFO_FLA TILT_35_
G
FLAG
Bit 3
SHAKE_
FLAG
Bit 2
Bit 1
ANYM_
FLIP_FLAG
FLAG
Bit 0
POR
Value
R/W
TILT_
FLAG
0x00
R
Description
This bit is active when the tilt feature in the motion control register (register 0x09,
bit 0) is enabled. If polling is used, use the tilt interrupt in the interrupt status
register (register 0x14, bit 0) instead because this bit can transition quickly.
0:
Tilt condition is not detected.
1:
Tilt condition is detected.
This bit is active when the flip feature in the motion control register (register
0x09, bit 0) is enabled. If polling is used, use the flip interrupt in the interrupt
status register (register 0x14, bit 1) instead because this bit can transition
quickly.
0:
Flip condition is not detected.
1:
Flip condition is detected.
This bit is active when the AnyMotion feature in the motion control register
(register 0x09, bit 2) is enabled. If polling is used, use the AnyMotion interrupt in
the interrupt status register (register 0x14, bit 2) instead because this bit can
transition quickly.
0:
AnyMotion condition is not detected.
1:
AnyMotion condition is detected.
This bit is active when the shake feature in the motion control register (register
0x09, bit 3) is enabled. If polling is used, use the shake interrupt in the interrupt
status register (register 0x14, bit 3) instead because this bit can transition
quickly.
0:
Shake condition is not detected.
1:
Shake condition is detected.
This bit is active when the tilt-35 feature in the motion control register (register
0x09, bit 4) is enabled. If polling is used, use the tilt-35 interrupt in the interrupt
status register (register 0x14, bit 4) instead because this bit can transition
quickly.
0:
Tilt-35 condition is not detected.
1:
Tilt-35 condition is detected.
This flag is an OR of the three FIFO flags from register 0x0A, FIFO_FULL,
FIFO_THRESH, and FIFO_EMPTY.
This bit is always active, only operates in WAKE mode, and is cleared and
rearmed each time this register is read. This flag is set when XYZ data is written
to registers 0x0D - 0x12. The host must poll this bit at the sample rate or faster to
see this bit transition.
0:
No data has been generated by the sensor since the last read.
1:
Data has been acquired and written to the output registers (0x0D - 0x12).
Table 34. Status Register
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12.12 (0X14) INTERRUPT STATUS REGISTER
The interrupt status register reports the status of any pending interrupt sources. Each interrupt
source must be enabled by the corresponding interrupt enable bit in register 0x06. All
interrupts are cleared each time this register is written (default). Individual interrupts may be
cleared using a bitmask if the INDIV_INTR_CLR bit is set in the communications control
register, address 0x31.
Addr
Name
0x14
INTR_
STAT
Description
Bit 7
Interrupt Status
ACQ_INT
Register
Name
TILT_INT
FLIP_INT
ANYM_INT
SHAKE_INT
TILT_35_INT
FIFO_INT
ACQ_INT
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Resv
FIFO_INT
TILT_35_
INT
SHAKE_
INT
ANYM_
INT
Bit 1
Bit 0
FLIP_INT TILT_INT
POR
R/W
Value
0x00
RW
Description
This bit is active when the tilt feature in the interrupt enable register (register
0x06, bit 0) is enabled and the tilt/flip feature in the motion control register
(register 0x09, bit 0) is enabled.
0: Tilt interrupt is not pending.
1: Tilt interrupt is pending.
This bit is active when the flip feature in the interrupt enable register (register
0x06, bit 1) is enabled and the tilt/flip feature in the motion control register
(register 0x09, bit 0) is enabled.
0: Flip interrupt is not pending.
1: Flip interrupt is pending.
This bit is active when the AnyMotion feature in the interrupt enable register
(register 0x06, bit 2) is enabled and the AnyMotion feature in the motion control
register (register 0x09, bit 2) is enabled.
0: AnyMotion interrupt is not pending.
1: AnyMotion interrupt is pending.
This bit is active when the shake feature in the interrupt enable register (register
0x06, bit 3) is enabled, the shake feature in the motion control register (register
0x09, bit 3) is enabled, and the AnyMotion feature in the motion control register
(register 0x09, bit 2) is enabled.
0: Shake interrupt is not pending.
1: Shake interrupt is pending.
This bit is active when the tilt-35 feature in the interrupt enable register (register
0x06, bit 4) is enabled, the tilt-35 feature in the motion control register (register
0x09, bit 4) is enabled, and the AnyMotion feature in the motion control register
(register 0x09, bit 2) is enabled.
0: Tilt-35 interrupt is not pending.
1: Tilt-35 interrupt is pending.
0: FIFO_INTR interrupt is not pending.
1: FIFO_INTR interrupt is pending.
This bit is an OR of the three FIFO interrupt flags from register 0x2F,
FIFO_FULL_INTR, FIFO_THRESH_INTR, and FIFO_EMPTY_INTR.
This bit only operates in WAKE mode. This bit is active when the interrupt
feature in the interrupt enable register (register 0x06, bit 7) is enabled.
0: Sample interrupt is not pending.
1: Sample interrupt is pending.
Table 35. Interrupt Status Register
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12.13 (0X20) RANGE AND SCALE CONTROL REGISTER
The range and scale control register sets the resolution, range, and filtering options for the
accelerometer. All values are in sign-extended 2’s complement format. Values are reported in
registers 0x0D – 0x12 (the hardware formats the output).
Addr
Name
Description
Bit 7
0x20
RANGE
Range Select
Control
01
1Software
Bit 6
Bit 5
Bit 4
Bit 3
RANGE[2] RANGE[1] RANGE[0] LPF_EN
Bit 2
Bit 1
Bit 0
LPF[2]
LPF[1]
LPF[0]
POR
R/W
Value
0x00
W
must write a zero (0) to bit 7.
Name
RANGE[2:0]
LPF_EN
LPF[2:0]
Description
Resolution range of the accelerometer, based on the current resolution.
000: ± 2g
001: ± 4g
010: ± 8g
011: ± 16g
100: ± 12g
101: Reserved.
110: Reserved.
111: Reserved.
0: Low pass Filter Disabled
1: Low Pass Filter Enabled
000: Reserved
001: Bandwidth setting 1, Fc = IDR / 4.255
010: Bandwidth setting 2, Fc = IDR / 6
011: Bandwidth setting 3, Fc = IDR / 12
100: Reserved
101: Bandwidth setting 5, Fc = IDR / 16
110: Reserved
111: Reserved
Table 36. Range and Scale Control Register
MEMSIC MC3479 APS-048-0072 v1.12
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12.14 (0X21 – 0X22) X-AXIS DIGITAL OFFSET REGISTERS
The X-axis digital offset registers contains a signed 2’s complement 14-bit value used to offset
the output of the X-axis filter. These registers are loaded from the OTP at device initialization
and POR. If necessary, these values can be overwritten by software.
Register 0x22 bit 7 is the ninth bit of X-axis gain (XGAIN). See X-Axis Digital Gain Registers
for more information about XGAIN.
NOTE: When modifying these registers with new gain or offset values, software should
perform a read-modify-write type of access to ensure that unrelated bits do not get changed.
Addr
Name
0x21
XOFFL
0x22
XOFFH
Description
X-Offset
LSB
X-Offset
MSB
Bit 0
POR
R/W
Value
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
XOFF[7]
XOFF[6]
XOFF[5]
XOFF[4]
XOFF[3]
XOFF[2]
XOFF[1]
XOFF[0] Per chip
W
XGAIN[8] XOFF[14] XOFF[13] XOFF[12] XOFF[11] XOFF[10] XOFF[9]
XOFF[8] Per chip
W
Table 37. X-Axis Digital Offset Registers
MEMSIC MC3479 APS-048-0072 v1.12
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12.15 (0X23 – 0X24) Y-AXIS DIGITAL OFFSET REGISTERS
The Y-axis digital offset registers contains a signed 2’s complement 14-bit value used to offset
the output of the Y-axis filter. These registers are loaded from the OTP at device initialization
and POR. If necessary, these values can be overwritten by software.
Register 0x24 bit 7 is the ninth bit of Y-axis gain (YGAIN). See Y-Axis Digital Gain Registers
for more information about YGAIN.
NOTE: When modifying these registers with new gain or offset values, software should
perform a read-modify-write type of access to ensure that unrelated bits do not get changed.
Addr
Name
0x23
YOFFL
0x24
YOFFH
Description
Y-Offset
LSB
Y-Offset
MSB
POR
R/W
Value
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
YOFF[7]
YOFF[6]
YOFF[5]
YOFF[4]
YOFF[3]
YOFF[2]
YOFF[1]
YOFF[0]
Per chip
W
YGAIN[8] YOFF[14] YOFF[13] YOFF[12] YOFF[11] YOFF[10] YOFF[9]
YOFF[8]
Per chip
W
Table 38. Y-Axis Digital Offset Registers
MEMSIC MC3479 APS-048-0072 v1.12
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12.16 (0X25 – 0X26) Z-AXIS DIGITAL OFFSET REGISTERS
The Z-axis digital offset registers contains a signed 2’s complement 14-bit value used to offset
the output of the Z-axis filter. These registers are loaded from the OTP at device initialization
and POR. If necessary, these values can be overwritten by software.
Register 0x26 bit 7 is the ninth bit of Z-axis gain (ZGAIN). See Z-Axis Digital Gain Registers
for more information about ZGAIN.
NOTE: When modifying these registers with new gain or offset values, software should
perform a read-modify-write type of access to ensure that unrelated bits do not get changed.
Addr
Name
0x25
ZOFFL
0x26
ZOFFH
Description
Z-Offset
LSB
Z-Offset
MSB
POR
R/W
Value
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ZOFF[7]
ZOFF[6]
ZOFF[5]
ZOFF[4]
ZOFF[3]
ZOFF[2]
ZOFF[1]
ZOFF[0]
Per chip
W
ZGAIN[8] ZOFF[14] ZOFF[13] ZOFF[12] ZOFF[11] ZOFF[10]
ZOFF[9]
ZOFF[8]
Per chip
W
Table 39. Z-Axis Digital Offset Registers
MEMSIC MC3479 APS-048-0072 v1.12
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12.17 (0X22 & 0X27) X-AXIS DIGITAL GAIN REGISTERS
The X-axis digital gain registers contains an unsigned 9-bit value. These registers are loaded
from the OTP at device initialization and POR. If necessary, these values can be overwritten
by software.
Register 0x22 bit 7 is the ninth bit of XGAIN.
NOTE: When modifying these registers with new gain values, software should perform a readmodify-write type of access to ensure that unrelated bits do not get changed.
Addr
Name
Description
0x22
XOFFH
X-Offset
MSB
0x27
XGAIN
X Gain
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
XGAIN[8] XOFF[14] XOFF[13] XOFF[12] XOFF[11] XOFF[10] XOFF[9]
Bit 0
POR
R/W
Value
XOFF[8] Per chip
W
XGAIN[7] XGAIN[6] XGAIN[5] XGAIN[4] XGAIN[3] XGAIN[2] XGAIN[1] XGAIN[0] Per chip
W
Table 40. X-Axis Digital Gain Registers
MEMSIC MC3479 APS-048-0072 v1.12
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12.18 (0X24 & 0X28) Y-AXIS DIGITAL GAIN REGISTERS
The Y-axis digital gain registers contains an unsigned 9-bit value. These registers are loaded
from the OTP at device initialization and POR. If necessary, these values can be overwritten
by software.
Register 0x24 bit 7 is the ninth bit of YGAIN.
NOTE: When modifying these registers with new gain values, software should perform a readmodify-write type of access to ensure that unrelated bits do not get changed.
Addr
Name
Description
0x24
YOFFH
Y-Offset
MSB
0x28
YGAIN
Y Gain
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
YGAIN[8] YOFF[14] YOFF[13] YOFF[12] YOFF[11] YOFF[10] YOFF[9]
Bit 0
YOFF[8]
POR
R/W
Value
Per chip
W
YGAIN[7] YGAIN[6] YGAIN[5] YGAIN[4] YGAIN[3] YGAIN[2] YGAIN[1] YGAIN[0] Per chip
W
Table 41. Y-Axis Digital Offset Registers
MEMSIC MC3479 APS-048-0072 v1.12
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12.19 (0X26 & 0X29) Z-AXIS DIGITAL GAIN REGISTERS
The Z-axis digital gain registers contains an unsigned 9-bit value. These registers are loaded
from the OTP at device initialization and POR. If necessary, these values can be overwritten
by software.
Register 0x26 bit 7 is the ninth bit of ZGAIN.
NOTE: When modifying these registers with new gain values, software should perform a readmodify-write type of access to ensure that unrelated bits do not get changed.
Addr
Name
Description
0x26
ZOFFH
Z-Offset
MSB
0x29
ZGAIN
Z Gain
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
ZGAIN[8] ZOFF[14] ZOFF[13] ZOFF[12] ZOFF[11] ZOFF[10]
Bit 1
Bit 0
ZOFF[9]
ZOFF[8]
POR
R/W
Value
Per chip
W
ZGAIN[7] ZGAIN[6] ZGAIN[5] ZGAIN[4] ZGAIN[3] ZGAIN[2] ZGAIN[1] ZGAIN[0] Per chip
W
Table 42. Z-Axis Digital Offset Registers
MEMSIC MC3479 APS-048-0072 v1.12
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12.20 (0X2D) FIFO CONTROL REGISTER
This register controls the options for the MC3479 FIFO. This register was previously undefined
in Mensa.
Addr
Name
0x2D FIFO_CTRL
Bit
Description
Bit 7
Bit 6
FIFO Control
Register
0
FIFO_
MODE
Bit 5
Bit 4
FIFO_EN FIFO_RESET
Bit 3
Bit 2
Bit 1
Bit 0
POR
R/W
Value
FIFO_
COMB_INT FIFO_TH_ FIFO_FULL_
EMPTY_
_EN
INT_EN
INT_EN
INT_EN
0x00
Name
Function
Description
0
FIFO_EMPTY_INT_EN
FIFO empty
interrupt
enable
0: FIFO empty interrupt enable is disabled (default)
1: FIFO empty interrupt enable is enabled.
1
FIFO_FULL_INT_EN
FIFO full
interrupt
enable
0: FIFO full interrupt enable is disabled (default)
1: FIFO full interrupt enable is enabled.
2
FIFO_TH_INT_EN
FIFO threshold
interrupt
enable.
0: FIFO threshold interrupt enable is disabled (default)
1: FIFO full threshold enable is enabled.
3
COMB_INT_EN
Combined
interrupt
enable
0: Motion/interrupt on sample interrupts are routed to
INTN1, and FIFO interrupts are routed to INTN2. (default).
1: All interrupts are routed to INTN1.
RW
When the COMB_INT_EN bit is set, all interrupts requests
are routed to INTN1, INTN2 becomes disabled.
4
FIFO_RESET
FIFO reset
control
0: FIFO is not reset (default)
1: FIFO is reset, read and write pointers are cleared.
In a FIFO reset, the contents of the FIFO are not cleared,
only the FIFO control logic, read and write pointers are
reset.
5
FIFO_EN
FIFO enable
MEMSIC MC3479 APS-048-0072 v1.12
0: FIFO and FIFO operations are disabled (default)
1: FIFO and FIFO operations are enabled.
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6
FIFO_MODE
FIFO mode
select
0: Normal operation, the FIFO continues to accept new
sample data as long as there is space remaining (default)
1: Watermark (threshold) mode, once the amount of
samples in the FIFO reaches or exceeds the threshold level,
the FIFO stops accepting new sample data. Any additional
sample data is “dropped”.
7
Reserved
Reserved
This bit must be ‘0’ for current FIFO operation.
Table 43. FIFO Control bit assignments
MEMSIC MC3479 APS-048-0072 v1.12
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12.21 (0X2E) FIFO THRESHOLD REGISTER
Addr
Name
0x2E FIFO_CTRL
Description
Bit 7
Bit 6
Bit 5
FIFO Threshold
Register
RESV
RESV
RESV
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
FIFO_TH[4] FIFO_TH[3] FIFO_TH[2] FIFO_TH[1] FIFO_TH[0]
POR
R/W
Value
0x10
RW
FIFO THRESHOLD SETTING
Register 0x2E holds the threshold or “watermark” level to apply to the number of samples in
the FIFO. Note that the POR default of the level is 0x10 (decimal 16), or ½ of the total size of
the FIFO.
Bit
Name
Description
4:0
FIFO_TH[4:0]
The FIFO threshold level selects the number of samples in the FIFO for
different FIFO events. The threshold value may be 1 to 31 (00001 to
11111).
7:5
RESV
Reserved, returns ‘0’ when read.
Table 44. FIFO Threshold level bit assignments
MEMSIC MC3479 APS-048-0072 v1.12
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12.22 (0X2F) FIFO INTERRUPT STATUS REGISTER
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
0x2E
FIFO_
INTR
FIFO Interrupt
Status Register
RESV
RESV
RESV
RESV
RESV
Bit 2
Bit 1
Bit 0
FIFO_
FIFO_FULL_ FIFO_EMPT
THRESH_
INT (RO) Y_INT (RO)
INT (RO)
POR
Value
R/W
0x00
R
Register 0x2F reports the status of any pending FIFO interrupts. The corresponding FIFO
interrupt enable bit must be enabled in register 0x2D for the interrupts to be detected.
Bit
0
Name
Function
Description
FIFO_EMPTY_INT
(RO)
FIFO Empty interrupt
flag.
0: No FIFO empty interrupt is pending.
1: FIFO empty interrupt is pending.
This read only bit reports the status of the FIFO empty interrupt.
It requires register 0x2B bit 0 be enabled.
1
FIFO_FULL_
INT (RO)
FIFO Full interrupt flag.
0: No FIFO full interrupt is pending.
1: FIFO full interrupt is pending.
This read only bit reports the status of the FIFO full interrupt.
It requires register 0x2B bit 1 be enabled.
2
7:3
FIFO_
THRESH_
INT (RO)
FIFO Threshold
interrupt flag.
RESV (RO)
Reserved
0: No FIFO threshold interrupt is pending.
1: FIFO threshold interrupt is pending.
This read only bit reports the status of the FIFO threshold interrupt.
It requires register 0x2B bit 2 be enabled.
Reserved bits, returns ‘00000’ when read.
Table 45. Interrupt status bit assignments
MEMSIC MC3479 APS-048-0072 v1.12
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12.23 (0X30) FIFO CONTROL REGISTER2, SAMPLE RATE REGISTER 2
This register controls the behavior of the FIFO burst mode, and the hardware decimation
feature of the MC3479.
The hardware decimation feature divides the internal data rate (IDR) generated by the
timebase module. Blocks at the end of signal acquisition pipeline may run at a slower output
data rate (ODR). The FIFO, motion, and interrupt blocks operate at the decimated rate while
the ADC and LPF filter operate at the higher internal rate. The hardware decimation feature is
disabled by default and can be applied to any data rate generated by the settings in register
0x08.
FIFO burst mode refers to the reading of multiple samples from the FIFO in the same
transaction. FIFO_BURST must be set to ‘1’ any time SW intends to drain more than one
sample in the same read cycle. It is not necessary to use FIFO_BURST mode for reading only
one sample at a time (single 6, 7, or 8-byte sequence).
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
0x30
FIFO_CTRL
2_SR2
FIFO Control
Register 2,
Sample Rate 2
Register
FIFO_
BURST_
MODE
0
Bit
Name
Function
Description
3:0
DEC_MODE_
RATE[3:0]
Decimation mode rate
selection.
0000: Decimation mode disabled (default).
0001: Divide sample rate by 2
0010: Divide sample rate by 4
0011: Divide sample rate by 5
0100: Divide sample rate by 8
0101: Divide sample rate by 10
0110: Divide sample rate by 16
0111: Divide sample rate by 20
1000: Divide sample rate by 40
1001: Divide sample rate by 67
1010: Divide sample rate by 80
1011: Divide sample rate by 100
1100: Divide sample rate by 200
1101: Divide sample rate by 250
1110: Divide sample rate by 500
1111: Divide sample rate by 1000
SELECT_
ENABLE_
WRAP_ADD
WRAP_N
R
Bit 3
Bit 2
Bit 1
Bit 0
POR
Value
DEC_MODE DEC_MODE DEC_MODE DEC_MODE
00000000
RATE[3]
RATE[2]
RATE[1]
RATE[0]
R/W
RW
When decimation mode is enabled, the internal data rate (IDR) is divided by
the above factor to create a slower output data rate (ODR). The FIFO, motion
block, output registers, and interrupts operate off the slower ODR when
decimation mode is on.
If decimation mode is disabled, then the IDR and ODR are the same value.
4
ENABLE_WRAP_N
Enable/disable automatic
address increment to
MEMSIC MC3479 APS-048-0072 v1.12
0: Internal register address pointer will “wrap” at address selected by bit 5
(default).
Page 66 of 80
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5
SELECT_WRAP_
ADDR
internal register file.
Applies to I2C and SPI
operations.
1: Internal register address pointer will increment to the next consecutive
value.
Select the register address
“wrap” value during burst
operations.
0: Internal register address wraps from address 0x12 to 0x0D on read cycles.
(default).
1: Internal register address wraps from address 0x14 to 0x0D on read cycles.
This bit determines which register address triggers a “wrap” to register 0x0D
(XOUT_LSB) during a read cycle. Address 0x12 is the MSB of the Z-axis data,
and address 0x14 is the address of the interrupt data register. Setting this bit
to a ‘1’ allows the contents of 0x13 (accel flag bits) and 0x14 (accel interrupt
flags) to be included in a read cycle that includes XOUT[15:0], YOUT[15:0],
ZOUT[15:0], STATUS[7:0], and INTR_STATUS[7:0].
6
Reserved
Reserved.
This bit must be ‘0’ for correct FIFO operation.
7
FIFO_BURST
Enable FIFO burst read
operations.
0: FIFO read cycle reads a single 6 byte XYZ sample from the FIFO (default).
1: FIFO read cycle reads 2 or more 6-byte XYZ samples (up to 32) from the
FIFO.
The length of the burst read must be set in the Read Count register, 0x4B.
Table 46. FIFO Control 2 bit assignments
MEMSIC MC3479 APS-048-0072 v1.12
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12.24 (0X31) COMMUNICATION CONTROL REGISTER
Addr
Name
Description
Bit 7
0x31
COMM_CTRL
Comm. Control
Register
Resv
Bit 6
Bit 5
Bit 4
INDIV_ SPI_3WIRE_ INT1_INT2_
INTR_CLR
EN
REQ_SWAP
Bit 3
Bit 2
Bit 1
Bit 0
POR
Value
R/W
0
0
RESV
RESV
0x00
RW
Bit
Name
Function
Description
0
RESV
Reserved
Reserved, returns ‘0’ when read.
1
RESV
Reserved
Reserved, returns ‘0’ when read.
2
RESV
Reserved
Reserved, this bit must be written to ‘0’ by software.
3
RESV
Reserved
Reserved, this bit must be written to ‘0’ by software.
4
INT1_INT2_REQ_S
WAP
Swap INT1 and INT2 pin
functionality.
0: INT1 requests are routed to the INTN1 pin, INT2 requests are
routed to the INTN2 pin (default).
1: INT1 requests are routed to the INTN2 pin, INT2 requests are
routed to the INTN1 pin.
5
SPI_3WIRE_EN
Enable SPI 3-wire mode.
0: SPI 3-wire more is disabled (default).
1: SPI 3-wire mode is enabled
When this bit is enabled, the DOUT_A6 pin becomes a bi-directional
data pin. SPI MISO and MOSI is applied to the DOUT_A6 pin. Note
that it is possible to simply tie the DIN_SDA and DOUT_A6 pins
together to enable 3-wire mode without using this bit.
6
INDIV_INTR_CLR
Enable individual interrupt mode.
0: Individual interrupt clear mode is disabled. All interrupts are
cleared by writing to register 0x14, contents of write cycle do not
matter. (default).
1: Individual interrupt clear mode is enabled. Individual interrupts
are cleared by writing to register 0x14 as a bitmask. Each bit of
register 0x14 controls a corresponding interrupt service/clear bit.
7
Reserved
Reserved
This bit must be ‘0’ for proper device operation.
Table 47. Communication Control bit assignments
MEMSIC MC3479 APS-048-0072 v1.12
Page 68 of 80
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12.25 (0X33) GPIO CONTROL REGISTER
This register is used to select the INTN1 pin and INTN2 pin polarity and drive mode when the
pins are used as interrupt request outputs.
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
POR
Value
R/W
0x33
GPIO_
CTRL
GPIO Control
Register
INTN2_
IPP
INTN2_IAH
RESV
RESV
INTN1_
IPP
INTN1_IAH
RESV
RESV
0x00
W
Bit
Name
Function
Description
1:0
Reserved
Reserved
Reserved
0: The INTN1 pin is active low.
1: The INTN1 pin is active high.
2
3
5:4
GPIO1_INTN1_IAH
GPIO1_INTN1_IPP
Reserved
Set polarity of INTN1 output.
Select open drain or push/pull mode
for INTN1.
Reserved
This bit sets the polarity level of the INTN1 pin. This bit is
used in interrupt mode to set the level of the interrupt
request.
0: The INTN1 pin operates in open-drain mode as an
output.
1: The INTN1 pin operates in push-pull mode as an
output.
This bit sets the drive mode of the INTN1 pin as an
interrupt request output. Open drain mode requires an
external pullup resistor.
Reserved
0: The INTN2 pin is active low.
1: The INTN2 pin is active high.
6
7
GPIO2_INTN2_IAH
GPIO2_INTN2_IPP
Set polarity of INTN2 output.
Select open drain or push/pull mode
for INTN2.
This bit sets the polarity level of the INTN2 pin. This bit is
used in interrupt mode to set the level of the interrupt
request, or in GPIO mode to set the level of the GPIO
output drive.
0: The INTN2 pin operates in open-drain mode as an
output.
1: The INTN2 pin operates in push-pull mode as an
output.
This bit sets the drive mode of the INTN2 pin as an
interrupt request output. Open drain mode requires an
external pullup resistor.
Table 48. GPIO Control Register
MEMSIC MC3479 APS-048-0072 v1.12
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12.26 (0X40 – 0X41) TILT/FLIP THRESHOLD REGISTERS
The tilt/flip threshold registers are used for both the flat/tilt/flip and tilt-35 algorithms.
For the flat/tilt/flip algorithm, these registers hold the programmed 15-bit threshold value to
detect the flat/tilt/flip position of the device. If the sample value is greater than the programmed
value of these registers, a tilt condition is detected. If the sample value is less than the
programmed value of these registers, a flat/flip condition is detected. A flat/flip condition is
dependent on the Z-axis value and the Z-axis orientation bit (register 0x09, bit 5).
For the tilt-35 algorithm, these registers hold the programmed 15-bit threshold value that
defines the amount of tilt to detect. When the programmed tilt is detected, the tilt-35 interrupt is
set in the interrupt status registers (register 0x14, bit 4).
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TF_
Tilt/Flip
TF_
0x40 THRESH_
TF_THR[7] TF_THR[6] TF_THR[5] TF_THR[4] TF_THR[3] TF_THR[2] TF_THR[1]
Threshold LSB
THR[0]
LSB
TF_
Tilt/Flip
TF_
TF_
TF_
TF_
TF_
TF_
0x41 THRESH_
Resv
TF_THR[9]
Threshold MSB
THR[14] THR[13] THR[12] THR[11] THR[10]
THR[8]
MSB
POR
R/W
Value
0x00
W
0x00
W
Table 49. Tilt/Flip Threshold Registers
MEMSIC MC3479 APS-048-0072 v1.12
Page 70 of 80
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12.27 (0X42) TILT/FLIP DEBOUNCE REGISTER
The tilt/flip debounce register holds the programmed 8-bit duration of a tilt/flip. When a tilt/flip
condition is detected and the duration of the condition is greater than the programmed value of
this register, the tilt/flip interrupt is set in the interrupt status registers (register 0x14, bits 0 and
1).
Addr
Name
Description
0x42
TF_DB
Tilt/Flip
Debounce
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TF_DB[7] TF_DB[6] TF_DB[5] TF_DB[4] TF_DB[3] TF_DB[2] TF_DB[1] TF_DB[0]
POR
R/W
Value
0x00
W
Table 50. Tilt/Flip Debounce Register
MEMSIC MC3479 APS-048-0072 v1.12
Page 71 of 80
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12.28 (0X43 – 0X44) ANYMOTION THRESHOLD REGISTERS
The Anymotion threshold registers hold the programmed 15-bit threshold value to detect a
change in the position of the device. If the change in position between the current sample
value and previous sample value on any axis is greater than the programmed value of this
register, an AnyMotion condition is detected. When the change in position exceeds the
programmed AnyMotion threshold, the AnyMotion interrupt is set in the interrupt status
registers (register 0x14, bit 2).
Addr
Name
Description
AM_
AnyMotion
0x43 THRESH_
Threshold LSB
LSB
AM_
AnyMotion
0x44 THRESH_
Threshold MSB
MSB
POR
R/W
Value
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ANYM_
THR[7]
ANYM_
THR[6]
ANYM_
THR[5]
ANYM_
THR[4]
ANYM_
THR[3]
ANYM_
THR[2]
ANYM_
THR[1]
ANYM_
THR[0]
0x00
W
Resv
ANYM_
THR[14]
ANYM_
THR[13]
ANYM_
THR[12]
ANYM_
THR[11]
ANYM_
THR[10]
ANYM_
THR[9]
ANYM_
THR[8]
0x00
W
Table 51. AnyMotion Threshold Registers
MEMSIC MC3479 APS-048-0072 v1.12
Page 72 of 80
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12.29 (0X45) ANYMOTION DEBOUNCE REGISTER
The AnyMotion debounce register holds the programmed 8-bit duration of any motion. After an
AnyMotion condition is detected, if another AnyMotion condition is not detected for the
programmed duration, the AnyMotion interrupt is cleared in the interrupt status registers
(register 0x14, bits 0 and 1).
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x45
AM_DB
AnyMotion
Debounce
ANYM_
DB[7]
ANYM_
DB[6]
ANYM_
DB[5]
ANYM_
DB[4]
ANYM_
DB[3]
ANYM_
DB[2]
ANYM_
DB[1]
ANYM_
DB[0]
POR
R/W
Value
0x00
W
Table 52. AnyMotion Debounce Register
MEMSIC MC3479 APS-048-0072 v1.12
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12.30 (0X46 – 0X47) SHAKE THRESHOLD REGISTERS
The shake threshold registers hold the programmed 15-bit threshold value to detect a shake. If
the change in position between the current sample value and previous sample value on any
axis is greater than the programmed value of this register, a shake condition is detected.
Addr
Name
Description
SHK_
Shake Threshold
0x46 THRESH_
LSB
LSB
SHK_
Shake Threshold
0x47 THRESH_
MSB
MSB
POR
R/W
Value
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
SH _
THR[7]
SH _
THR[6]
SH _
THR[5]
SH _
THR[4]
SH _
THR[3]
SH _
THR[2]
SH _
THR[1]
SH _
THR[0]
0x00
W
SH_
THR[15]
SH _
THR[14]
SH _
THR[13]
SH _
THR[12]
SH _
THR[11]
SH _
THR[10]
SH _
THR[9]
SH _
THR[8]
0x00
W
Table 53. Shake Threshold Registers
MEMSIC MC3479 APS-048-0072 v1.12
Page 74 of 80
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12.31 (0X48 – 0X49) SHAKE DURATION, PEAK-TO-PEAK REGISTERS
The shake duration and peak-to-peak registers hold the programmed 12-bit threshold value of
a peak and the peak-to-peak width of a shake and the programmed 3-bit threshold value of the
shake counter.
The data in these registers and the shake threshold registers is used to determine if the shake
interrupt should be set.
If a shake condition is detected, the shake counter is incremented and the shake’s peak is
detected and measured. If the peak’s width is greater than the peak threshold set in this
register, the shake counter continues to increment (measuring the duration of the peak event).
When a shake condition is no longer detected, the peak-to-peak event is measured and the
shake counter continues to increment (measuring the duration of the peak-to-peak event).
When the peak-to-peak threshold is surpassed, the shake counter continues to increment,
measuring the duration of the peak event. The shake counter continues to increment each time
a peak or peak-to-peak threshold is surpassed. When the shake counter threshold is
surpassed, the shake interrupt is set in the interrupt status registers (register 0x14, bit 3).
Addr
Name
Description
Bit 7
Bit 6
Bit 5
Bit 4
PK_P2P_
DUR_
Peak-to-Peak
PK_P2P_ PK_P2P_ PK_P2P_ PK_P2P_
0x48
THRESH_ Duration LSB
DUR[7] DUR[6]
DUR[5] DUR[4]
LSB
PK_P2P_
Shake Duration
DUR_
SHK_CNT_ SHK_CNT_ SHK_CNT_
0x49
and Peak-to-Peak
Resv
THRESH_
DUR[2]
DUR[1] DUR[0]
Duration MSB
MSB
Bit 3
Bit 2
Bit 1
Bit 0
POR
R/W
Value
PK_P2P_ PK_P2P_ PK_P2P_ PK_P2P_
DUR[3]
DUR[2]
DUR[1] DUR[0]
0x00
W
PK_P2P_ PK_P2P_ PK_P2P_ PK_P2P_
DUR[11] DUR[10] DUR[9] DUR[8]
0x00
W
Table 54. Shake Duration and Peak-to-Peak Registers
MEMSIC MC3479 APS-048-0072 v1.12
Page 75 of 80
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12.32 (0X4A) TIMER CONTROL REGISTER
The timer control register sets the period or duration of two features driven by the 10 Hz low
speed clock.
Addr
Name
Description
0x4A
TIMER_
CTRL
Timer Control
Bit 7
Bit 6
Bit 5
Bit 4
TEMP_
TEMP_
TEMP_
TEMP_
PER_INT_
PERIOD[2] PERIOD[1] PERIOD[0]
EN
Bit 3
Bit 2
Bit 1
Bit 0
POR
R/W
Value
Resv
TILT_
35[2]
TILT_35[1]
TILT_
35[0]
0x00
W
Name
Description
Duration of a valid tilt-35 angle detection.
000: 1.6 s (default)
001: 1.8 s
010: 2.0 s
TILT_35[2:0]
011: 2.2 s
100: 2.4 s
101: 2.6 s
110: 2.8 s
111: 3.0 s
Timeout or re-arm time for the temporary latch on the TEST_INT pin.
000: 200 ms (default)
001: 400 ms
010: 800 ms
TEMP_PERIOD[2:0] 011: 1600 ms
100: 3200 ms
101: 6400 ms
110: Reserved
111: Reserved
Temporary latch.
TEMP_PER_INT_EN 0: The temporary latch feature is disabled (default).
1: The temporary latch feature is enabled.
Table 55. Timer Control Register
MEMSIC MC3479 APS-048-0072 v1.12
Page 76 of 80
2021/05
12.33 (0X4B) READ COUNT REGISTER
The read count register (0x4B) sets length of FIFO burst read transactions.
Addr
Name
Description
0x4B
RD_CNT
Read Count
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RD_CNT[7] RD_CNT[6] RD_CNT[5] RD_CNT[4] RD_CNT[3] RD_CNT[2] RD_CNT[1] RD_CNT[0]
POR
R/W
Value
0x06
RW
Bit
Name
Function
Description
7:0
RD_CNT[7:0]
Sample count to be 0x06: POR value (default)
used during I2C/SPI If register 0x30 bit 7 (FIFO_BURST) is enabled, this
read cycles.
register is the number of samples to be read in single
burst read transaction. A sample is one 6-byte sample
from the FIFO and optionally one or two status bytes
from registers 0x13 and 0x14 (a sample can be 6, 7, or
8-bytes long). Note this parameter is a sample count,
not a byte count.
If FIFO burst mode is disabled, this parameter is not
used.
Table 56. Read Count Register
MEMSIC MC3479 APS-048-0072 v1.12
Page 77 of 80
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13
INDEX OF TABLES
Table 1. Order Information.........................................................................................................................................5
Table 2. Package Information .....................................................................................................................................5
Table 3. Pin Description ..............................................................................................................................................9
Table 4. Absolute Maximum Ratings ....................................................................................................................... 16
Table 5. Sensor Characteristics................................................................................................................................ 17
Table 6. Electrical Characteristics ............................................................................................................................ 18
Table 7. Electrical and Timing Characteristics - Interface ....................................................................................... 19
Table 8. I2C Timing Characteristics.......................................................................................................................... 20
Table 9. SPI Interface Timing Parameters ............................................................................................................... 21
Table 10. Summary of Resolution, Range, and Scaling ........................................................................................... 22
Table 11. Operational States ................................................................................................................................... 23
Table 12. Forcing Operational States ...................................................................................................................... 24
Table 13. Interrupt Overview .................................................................................................................................. 25
Table 14. Interrupt servicing details (Motion + Sample) ......................................................................................... 29
Table 15. Interrupt servicing details (FIFO) ............................................................................................................. 29
Table 16. GPIO Control Register .............................................................................................................................. 30
Table 17. Interrupt drive and polarity control......................................................................................................... 30
Table 18. Swapping Interrupt Requests, register 0x31 bit 4 ................................................................................... 31
Table 19. Combining interrupt requests, register 0x2D bit 3 .................................................................................. 31
Table 20. Sample Rate Settings ............................................................................................................................... 32
Table 21. Hardware Decimation Ratios ................................................................................................................... 34
Table 22. I2C Address Selection .............................................................................................................................. 35
Table 23. Register Summary .................................................................................................................................... 43
Table 24. Device Status Register ............................................................................................................................. 44
Table 25. Interrupt Enable Register......................................................................................................................... 45
Table 26. Mode Register States ............................................................................................................................... 46
Table 27. Sample Rate Register ............................................................................................................................... 47
Table 28. Sample Rate Values ................................................................................................................................. 47
Table 29. Motion Control Register .......................................................................................................................... 48
Table 12-30: FIFO read pointer, register 0x0B ........................................................................................................ 50
Table 12-31: FIFO write pointer, register 0xC ......................................................................................................... 51
Table 32. Accelerometer LSB and MSB Registers .................................................................................................... 52
MEMSIC MC3479 APS-048-0072 v1.12
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Table 33. Status Register ......................................................................................................................................... 53
Table 34. Interrupt Status Register ......................................................................................................................... 54
Table 35. Range and Scale Control Register ............................................................................................................ 55
Table 36. X-Axis Digital Offset Registers .................................................................................................................. 56
Table 37. Y-Axis Digital Offset Registers .................................................................................................................. 57
Table 38. Z-Axis Digital Offset Registers .................................................................................................................. 58
Table 39. X-Axis Digital Gain Registers .................................................................................................................... 59
Table 40. Y-Axis Digital Offset Registers .................................................................................................................. 60
Table 41. Z-Axis Digital Offset Registers .................................................................................................................. 61
Table 42. FIFO Control bit assignments ................................................................................................................... 63
Table 43. FIFO Threshold level bit assignments ...................................................................................................... 64
Table 44. Interrupt status bit assignments .............................................................................................................. 65
Table 45. FIFO Control 2 bit assignments ................................................................................................................ 67
Table 46. Communication Control bit assignments ................................................................................................ 68
Table 47. GPIO Control Register .............................................................................................................................. 69
Table 48. Tilt/Flip Threshold Registers .................................................................................................................... 70
Table 49. Tilt/Flip Debounce Register ..................................................................................................................... 71
Table 50. AnyMotion Threshold Registers .............................................................................................................. 72
Table 51. AnyMotion Debounce Register................................................................................................................ 73
Table 52. Shake Threshold Registers ....................................................................................................................... 74
Table 53. Shake Duration and Peak-to-Peak Registers ........................................................................................... 75
Table 54. Timer Control Register ............................................................................................................................. 76
Table 55. Read Count Register ................................................................................................................................ 77
MEMSIC MC3479 APS-048-0072 v1.12
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14
REVISION HISTORY
Date
2019-05
2019-06
2020-06
Revision
APS-048-0072v1.0
APS-048-0072v1.01
APS-048-0072v1.1
2021-05
APS-048-0072v1.2
MEMSIC MC3479 APS-048-0072 v1.12
Description
Initial release
Fixed a few formatting issues
Change to MEMSIC format based on the License
Agreement with mCube.
Update Tape and reel 10Ku
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