VK202-25
Including VK202-25-USB
Technical Manual
Revision 4.1
PCB Revision: 3.0 or Higher (Standard Model), 1.0 or Higher (USB Model)
Firmware Revision: 5.6 or Higher
Revision History
Revision
4.1
4.0
Date
January 4, 2018
January 8, 2016
Description
Correction to Set Non-Standard Baud Rate command
LKVK manual separated into individual manuals
Author
Divino
Divino
Contents
1 Introduction ............................................................................................................................................... 1
2 Quick Connect Guide.................................................................................................................................. 2
2.1 Available Headers ............................................................................................................................... 2
2.2 Standard Module ................................................................................................................................ 3
Recommended Parts ............................................................................................................................. 3
Serial Connections................................................................................................................................. 3
I2C Connections ..................................................................................................................................... 4
2.3 USB Module ........................................................................................................................................ 5
Recommended Parts ............................................................................................................................. 5
USB Connections ................................................................................................................................... 5
3 Software ..................................................................................................................................................... 6
3.1 uProject ............................................................................................................................................... 6
3.2 Application Notes................................................................................................................................ 7
4 Hardware.................................................................................................................................................... 8
4.1 Standard Model .................................................................................................................................. 8
Communication/Power Header ............................................................................................................ 8
Serial DB9 Connector ............................................................................................................................ 8
Power Through DB9 Jumper ................................................................................................................. 9
Protocol Select Jumpers ........................................................................................................................ 9
4.2 USB Model......................................................................................................................................... 10
Mini USB Connector ............................................................................................................................ 10
Alternate USB Header ......................................................................................................................... 10
Alternate Power Connector ................................................................................................................ 10
4.3 Common Features ............................................................................................................................. 11
General Purpose Outputs ................................................................................................................... 11
Dallas One-Wire Connector ................................................................................................................ 11
Keypad Header .................................................................................................................................... 12
5 Troubleshooting ....................................................................................................................................... 13
5.1 Power ................................................................................................................................................ 13
5.2 Display ............................................................................................................................................... 13
5.3 Communication ................................................................................................................................. 14
5.4 Manual Override ............................................................................................................................... 14
6 Commands ............................................................................................................................................... 15
6.1 Communication ................................................................................................................................. 15
6.2 Text.................................................................................................................................................... 16
6.3 Special Characters ............................................................................................................................. 18
6.4 General Purpose Output ................................................................................................................... 20
6.5 Dallas One-Wire ................................................................................................................................ 21
6.6 Keypad............................................................................................................................................... 22
6.7 Display Functions .............................................................................................................................. 23
6.8 Data Security ..................................................................................................................................... 24
6.9 Miscellaneous ................................................................................................................................... 25
7 Appendix .................................................................................................................................................. 26
7.1 Command Summary ......................................................................................................................... 26
7.2 Character Sets ................................................................................................................................... 29
7.3 Block Diagram ................................................................................................................................... 30
7.4 Environmental Specifications............................................................................................................ 30
7.5 Electrical Tolerances ......................................................................................................................... 30
7.6 Dimensional Drawings ...................................................................................................................... 31
7.7 Optical Characteristics ...................................................................................................................... 32
8 Ordering ................................................................................................................................................... 32
8.1 Part Numbering Scheme ................................................................................................................... 32
8.2 Options .............................................................................................................................................. 32
8.3 Accessories ........................................................................................................................................ 33
9 Definitions ................................................................................................................................................ 35
10 Contact ................................................................................................................................................... 35
1 Introduction
Figure 1: VK202-25 Display
The VK202-25 is an intelligent alphanumeric liquid crystal display designed to decrease development
time by providing an instant solution to any project. In addition to the RS232, TTL and I2C protocols
available in the standard model, a USB communication model allow the VK202-25 to be connected to a
wide variety of host controllers. Communication speeds of up to 115.2kbps for serial protocols and
100kbps for I2C ensure lightning fast display updates.
The simple command structure permits easy software control of many settings including backlight
brightness, screen contrast, and baud rate. On board memory provides up to forty custom characters
which can be saved within the unit and recalled for start screens, bar graphs or larger numbers.
User input on the VK202-25 is available through a five by five matrix style keypad, and six general
purpose outputs provide simple switchable five volt sources. In addition, the option of a Dallas OneWire header provides a communication interface for up to thirty-two devices.
The versatile VK202-25, with all the features mentioned above, is available in a variety of colour,
voltage, and temperature options to suit almost any application.
1
2 Quick Connect Guide
2.1 Available Headers
Figure 2: VK202-25 Standard Module Header Locations
Figure 3: VK202-25 USB Model Header Locations
Table 1: List of Available Headers
#
1
2
3
4
5
6
7
Header
GPO Header
DB9 Serial Header
Keypad
Communication/Power Connector
Mini USB Connector
Dallas One-Wire Header
Alternate Power Connector
Mate
None Offered
CSS1FT/CSS4FT
KPP4x4
SCCPC5V/BBC
EXTMUSB3FT/INTMUSB3FT
Temperature Probe
PCS
Population
All Models
Standard Model Only
All Models
Standard Model Only
USB Model Only
USB Model Only
USB Model Only
2
2.2 Standard Module
The standard version of the VK202-25 allows for user configuration of three common communication
protocols. First, the unit can communicate using serial protocol at either RS323 or TTL voltage levels.
Second, it can communicate using the Inter-Integrated Circuit connect, or I2C protocol. Connections for
each protocol can be accessed through the four pin Communication/Power Header as outlined in the
Serial Connections and I2C Connections sections below.
Recommended Parts
The most common cable choice for any alphanumeric Matrix Orbital
Display, the Communication/ Power Cable offers a simple connection
to the unit with familiar interfaces. DB9 and floppy power headers
provide all necessary input to drive your display.
Figure 4: Communication/Power Cable
(SCCPC5V)
For a more flexible interface to the VK202-25 a Breadboard Cable may
be used. This provides a simple four wire connection that is popular
among developers for its ease of use in a breadboard environment.
Figure 5: Breadboard Cable (BBC)
Serial Connections
A serial interface provides a classic connection to the VK202-25. The Communication/Power Cable is
most commonly used for this set up as it provides connections for DB9 serial and floppy power cables.
To place your board in Serial mode, adhere to the steps laid out below.
1. Set the Protocol Select jumpers.
RS232: Connect the three jumpers* in the 232 protocol box with the zero ohm jumper resistors
provided or an alternate wire or solder solution.
TTL: Connect the two jumpers* in the TTL protocol box.
*Note: Jumpers must be removed from all protocol boxes save for the one in use.
3
2. Make the connections.
a. Connect the four pin female header of the Communication/Power Cable to the
Communication/Power Header of your VK202-25.
b. Insert the male end of your serial cable to the corresponding DB9 header of the
Communication/Power Cable and the mate the female connector with the desired
communication port of your computer.
c. Select an unmodified floppy cable from a PC power supply and connect it to the power header
of the Communication/Power Cable.
3. Create.
Use uProject or a terminal program to get started, and then move on with your own
development. A number of application notes are available at www.matrixorbital.ca/appnotes.
I2C Connections
A more advanced connection to the VK202-25 is provided by the I2C protocol setting. This is best
accomplished using a breadboard and the Breadboard Cable. Power must be supplied from your
breadboard or another external source. To dive right into your application and use the VK202-25 in I2C
mode, get started with the guidelines below.
1. Set the Protocol Select switches.
I2C: Ensure that the two I2C jumpers in the corresponding protocol box are connected while all
others are open.
2. Make the connections.
a. Connect the Breadboard Cable to the Communication/Power Header on your VK202-25 and
plug the four leads into your breadboard. The red lead will require power, while the black
should be connected to ground, and the green and yellow should be connected to your
controller clock and data lines respectively.
b. Pull up the clock and data lines to five volts using a resistance between one and ten kilohms on
your breadboard.
3. Create.
This time you're on your own. While there are many examples within the Matrix Orbital
AppNote section, www.matrixorbital.ca/appnotes, too many controllers and languages exist to
cover them all. If you get stuck in development, it is possible to switch over to another protocol
on the standard board, and fellow developers are always on our forums for additional support.
4
2.3 USB Module
The VK202-25-USB offers a single USB protocol for an easy connection to a host computer. This simple
and widely available protocol can be accessed using the on board mini B style USB connector as outlined
in the USB Connections section.
Recommended Parts
The External Mini USB cable is recommended for the VK202-25-USB display.
It will connect to the miniB style header on the unit and provide a
connection to a regular A style USB connector, commonly found on a PC.
Figure 6: External Mini USB
Cable (EXTMUSB3FT)
USB Connections
The USB connection is the quickest, easiest solution for PC development. After driver installation, the
VK202-25-USB will be accessible through a virtual serial port, providing the same result as a serial setup
without the cable hassle. To connect to your VK202-25-USB please follow the steps below.
1. Set the Protocol Select jumpers.
USB: The VK202-25-USB offers USB protocol only. Model specific hardware prevents this unit
from operating in any other protocol, and does not allow other models to operate in USB.
Protocol Select jumpers on the USB model cannot be moved.
2. Make the connections.
Plug the mini-B header of your External Mini USB cable into your VK202-25-USB and the regular
USB header into your computer USB jack.
3. Install the drivers.
a. Download the latest drivers at www.matrixorbital.ca/drivers, and save them to a known
location.
b. When prompted, install the USB bus controller driver automatically
c. If asked, continue anyway, even though the driver is not signed
d. When the driver install is complete, your display will turn on, but communication will not yet be
possible.
e. At the second driver prompt, install the serial port driver automatically
f. Again, if asked, continue anyway
4. Create.
Use uProject or a terminal program to get started, and then move on with your own
development. A number of application notes are available at www.matrixorbital.ca/appnotes.
5
3 Software
The multiple communication protocols available and simple command structure of the VK202-25 means
that a variety of applications can be used to communicate with the display. Text is sent to the display as
a character string, for example, sending the decimal value 41 will result in an 'A' appearing on the
screen. A number of control characters are also activated. Commands are merely values prefixed with a
special command byte, 254 in decimal.
Table 2: Reserved Control Characters
8
Backspace
10
Control Characters
Line feed / New line 12 Clear screen / New page
13
Carriage return
Once the correct communication port is identified, the following communication settings can be applied
to communicate correctly with the VK202-25.
Table 3: Communication Settings
BPS
19200
Data Bits
8
Parity
None
Stop Bits
1
Flow Control
None
Finally, with a communication port identified and correctly setup simple text strings or even command
bytes can easily be transmitted to control your display.
3.1 uProject
The Matrix Orbital alphanumeric display tuner, or uProject, is offered as a free download from the
www.matrixorbital.ca support site. It allows the basic functionality of *any display to be tested using a
simple graphical user interface system.
While basic functionality can be tested using the GUI portion of the program, more advanced users will
enjoy the scripting capability found in the uploader tab. Here commands can be stacked, run, and saved
for later use. Although many commands are available to be dragged into the script dialog, perhaps the
most powerful is the raw data command found in the other branch.
*Note: The uProject AutoDetect function will not perform correctly when a USB display is connected. Please
manually configure any USB display.
6
This command allows raw bytes to be sent to the display, permitting many different formats for entry
and displaying in decimal notation. Any command from this manual may be entered in decimal notation
separated by slashes.
/254/ /88/
Figure 7: uProject Command
Again, the clear screen command is sent to a connected display, this time using uProject raw data
command style. Scripts can be run as a whole using the execute command from the script menu, or as
single commands by selecting execute once. Before issuing commands, it is a good idea to ensure
communication with a display is successful using some of the more basic GUI functions in the main
window.
This program provides scratch pad upon which a tome of display projects and ideas can be assembled.
3.2 Application Notes
Full demonstration programs and code are available for Matrix Orbital Displays in the C# language from
Simple C# AppNote Pack in the Application Note section at www.matrixorbital.ca/appnotes. Difficulty
increases from beginner, with the Hello World program, to advanced with the Dallas One-Wire
temperature reading application.
Many additional applications are available in a number of different programming languages. These
programs are meant to showcase the capability of the display and are not intended to be integrated into
a final design. For additional information regarding code, please read the On Code document also found
on the support site.
7
4 Hardware
4.1 Standard Model
Communication/Power Header
Table 4: Communication/Power Pinout
Pin
1
2
3
4
Function
Vcc
Rx (SCL)
Tx (SDA)
Gnd
Figure 8: Communication/Power Header
The Communication/Power Header provides a standard connector for interfacing to the VK202-25.
Voltage is applied through pins one and four of the four pin Communication/Power Header. Please
ensure the correct voltage input for your display by referencing Voltage Specifications before connecting
power. Pins two and three are reserved for serial transmission, using either the RS-232/TTL or clocking
data through the I²C protocol, depending on what has been selected by the Protocol Select Jumpers.
The versatile Tyco 640456-4-LF style header used can be mated to a number of connectors, the Molex
22-01-3047 for example.
Serial DB9 Connector
Table 5: Serial DB9 Pinout
Figure 9: Serial DB9 Connector
Pin
2
3
5
9
Function
Tx
Rx
Gnd
NC/Vcc*
The VK202-25 provides a DB-9 Connector to readily interface with serial devices using EIA232 standard
signal levels. It is also possible to communicate at TTL levels of 0 to +5V by setting the Protocol Select
Jumpers to TTL. As an added feature it is also possible to apply power through pin 9 of the DB-9
Connector in order to reduce cable clutter. A standard male DB9 header will provide the perfect mate
for this connector.
*Note: Do not apply voltage through pin 9 of the DB-9 Connector AND through the Communication/Power Header
at the same time.
8
Power Through DB9 Jumper
In order to provide power through pin 9 of the DB-9 Connector you must connect the Power Through
DB-9 Jumper labelled D, as illustrated below. This connection can be made using a zero ohm resistor,
recommended size 0603, or a solder bridge. The VK202-25 allows all voltage models to use the power
through DB-9 option, see the Voltage Specifications for power requirements.
Figure 10: Power Through DB9 Jumper
Protocol Select Jumpers
The Protocol Select Jumpers provide the means necessary to toggle the VK202-25 between RS-232, TTL
and I²C protocols. As a default, the jumpers are set to RS-232 mode with solder jumps on the RS232
jumpers. In order to place the display module in I²C mode you must first remove the solder jumps from
the RS232 jumpers and then place them on the I2C jumpers. The display will now be in I²C mode and
have a default slave address of 80, unless changed with the appropriate command. Similarly, in order to
change the display to TTL mode, simply remove the zero ohm resistors from the RS232 or I²C jumpers
and solder them to the TTL jumpers.
9
4.2 USB Model
Mini USB Connector
Table 6: Mini USB Pinout
Figure 11: Mini USB Connector
Pin
1
2
3
5
Function
Vcc
DD+
Gnd
The VK202-25-USB comes with a familiar Mini USB Connector to fulfill both communication and power
needs. The standard MiniB style header can be connected to any other USB style using the appropriate
cable. Most commonly used with a PC, this connection creates a virtual com port that offers a simple
power solution with a familiar communication scheme.
Alternate USB Header
Some advanced applications may prefer the straight four pin connection offered through the Optional
Alternate USB Header. This header offers power and communication access in a simple interface
package. The Optional Alternate USB Header may be added to the VK202-25-USB for an added charge
as part of a custom order. Please use the Contact section to request more information from the friendly
Matrix Orbital sales team.
Alternate Power Connector
Table 7: Alternate Power Pinout
Figure 12: Alternate Power Connector
Pin
1
2
3
4
Function
Vcc
Gnd
Gnd
NC
The Alternate Power Connector provides the ability to power the VK202-25-USB using a second cable.
The Tyco 171825-4 style header is particularly useful for connecting to an unmodified floppy power
cable, a 171822-4 for example, from a PC power supply for a simple bench power solution.
10
4.3 Common Features
General Purpose Outputs
Table 8: GPO Pinout
Figure 13: GPO Header
Pin
1
2
3
4
5
6
7
Function
GPO 1
GPO 2
GPO 3
GPO 4
GPO 5
GPO 6
Vcc
Pin
8
9
10
11
12
13
14
Function
Gnd
Gnd
Gnd
Gnd
Gnd
Gnd
Gnd
A unique feature of the VK202-25 is the ability to control relays* and other external devices using either
one or six General Purpose Outputs. Each can source up to 10mA of current at five volts when on or sink
20mA at zero volts when off. The two row, fourteen pin header can be interfaced to a number of female
connectors to provide control to any peripheral devices required.
*Note: If connecting a relay, be sure that it is fully clamped using a diode and capacitor in order to absorb any
electro-motive force (EMF) which will be generated.
Dallas One-Wire Connector
Table 9: Dallas One-Wire Pinout
Figure 14: Dallas One-Wire Connector
Pin
1
2
3
Function
Vcc
D
Gnd
In addition to the six general purpose outputs the VK202-25 offers an Optional Dallas One-Wire bridge,
to allow for an additional thirty two one-wire devices to be connected to the display. This header can be
populated with a Tyco 173979 connector at an added cost by custom order only. Please use the Contact
section to request more information from the Matrix Orbital sales team.
11
Keypad Header
Table 10: Keypad Pinout
Figure 15: Keypad Header
Pin
1
2
3
4
5
6
Function
Gnd
Row 1
Row 2
Row 3
Row 4
Row 5
Pin
7
8
9
10
11
12
Function
Column 1
Column 2
Column 3
Column 4
Column 5
Gnd/Vcc*
To facilitate user input, the VK202-25 provides a Keypad Interface Connector which allows a matrix style
keypad of up to twenty-five keys to be directly connected to the display module. Key presses are
generated when a short is detected between a row and a column. When a key press is generated, a
character specific to that key press is automatically sent on the Tx communication line. If the display
module is running in I²C mode, the “Auto Transmit Keypress” function may be turned off to allow the
key presses to remain in the buffer so that they may be polled. The character that is associated with
each key press may also be altered using the “Assign Key Codes” command. The straight twelve pin
header of the Keypad Interface Connector will interface to a variety of different devices including the
Matrix Orbital KPP4x4 keypad.
*Note: The Ground / +5V pin is toggled by the jumper to the right of the keypad connector. Jump pads 1 & 2 for
+5V or 2 & 3 for GND.
12
5 Troubleshooting
5.1 Power
In order for your VK202-25 to function correctly, it must be supplied with the appropriate power. If the
screen is not illuminated, power may not be applied correctly. Try the tips below.
First, make sure that you are using the correct power connector. Standard floppy drive power
cables from your PC power supply may fit on the Communication/Power Header; however they
do not have the correct pin out to provide power. Matrix Orbital supplies power cable adapters
for connecting to a PC, which can be found in the Accessories section.
Next, check the power cable which you are using for continuity. If you don't have an ohm
meter, try using a different power cable, if this does not help try using a different power supply.
If power is applied through the DB9 connector, ensure that the Power Through DB9 Jumper is
connected.
If changes have been made to the protocol select block, ensure all the appropriate protocol
select jumpers are connected and all unused protocol jumpers are disconnected.
The last step will be to check the interface connector in use on your display. If the power
connections have become loose, or you are unable to resolve the issue, please Contact Matrix
Orbital for more information.
5.2 Display
If your display is powered successfully, the Matrix Orbital logo, or user created screen should display on
start up. If this is not the case, check out these tips.
•
•
13
Ensure the contrast is not too high or too low. This can result in a darkened or blank screen
respectively. See the Manual Override section to reset to default.
Make sure that the start screen is not blank. It is possible to overwrite the Matrix Orbital logo
start screen, if this happens the screen may be blank. Try writing to the display to ensure it is
functional, after checking the contrast above.
5.3 Communication
When communication of either text or commands is interrupted, try the steps below.
•
•
•
•
•
•
•
•
First, check the communication cable for continuity. If you don't have an ohm meter, try using a
different communication cable. If you are using a PC try using a different Com/USB Port.
Next, please ensure that the display module is set to communicate on the protocol that you are
using, by checking the Protocol Select Jumpers.
In serial and USB protocols, ensure that the host system and display module are both
communicating on the same baud rate. The default rate for the display module is 19200 bps.
Match Rx from your display to the transmitting pin from your host and the Tx pin to the
receiving pin.
If you are communicating to the display via I²C* please ensure that the data is being sent to the
correct address. The default slave address for the display module is 80.
In I2C mode, connect Rx to the clock line of your controller and Tx to the data output.
Unlock the display. See the Set and Save Data Lock command for more info.
Finally, you may reset the display to its default settings using the Manual Override procedure
outlined below.
*Note: I²C communication will always require pull up resistors on SCL and SDA of one to ten kilohms.
5.4 Manual Override
Should the settings of your display become altered in a way that dramatically impacts usability, the
default settings can be temporarily restored. To override the display, please follow the steps below.
1.
2.
3.
4.
Disconnect power from your display.
Place a jumper on the middle two keypad pins, R5 and C1.
Reconnect power to your unit, and wait for the start screen before removing the jumper.
Settings will be temporarily** overridden to the defaults listed in the Manual Override Settings
table. At this point any important settings, such as contrast, backlight, or baud rate, should not only
be set but saved so they remain when the override is removed.
Parameter
Backlight
Contrast
Baud Rate
2
I C Address
Value
255
128
19200
80
Table 11: Manual Override Settings
**Note: The display module will revert back to the old settings once turned off, unless desired settings are saved.
14
6 Commands
6.1 Communication
1.1 Change
Baud Rate
Dec
254 57 Speed
Hex
FE 39 Speed
ASCII
■ 9 Speed
Immediately changes the baud rate. Not available in I2C. Baud rate can be temporarily forced to 19200 by a
manual override.
Speed Byte Valid settings shown below.
v5.6
Table 12: Accepted Baud Rate Values
Rate
Speed
1200
83
2400
41
4800
207
9600
103
19200
51
28800
34
38400
25
57600
16
*76800
12
*115200
8
*Note: Baud rates 76800 and 115200 added with the release of firmware revision 5.7 as per PCN 2006-08-24.
2
1.2 Change I C
Slave Address
Dec
254 51 Address
v5.6
Hex
FE 33 Address
ASCII
■ 3 Address
2
Immediately changes the I C write address. Only even values are permitted as the next odd address will become
the read address. Default is 80.
Address Byte Even value.
1.3 Transmission
Protocol Select
Dec
254 160 Protocol
v5.6
Hex
FE A0 Protocol
ASCII
■ á Protocol
Selects the protocol used for data transmission from the display. Data transmission to the display is not affected.
Must be set to the protocol in use to receive data correctly.
2
Protocol Byte
1 for Serial (RS232/RS422/TTL/USB) or 0 for I C.
1.4 Set a Non-Standard
Baud Rate
Dec
254 164 Speed
v5.0
Hex
FE A4 Speed
ASCII
■ ñ Speed
Immediately changes the baud rate to a non-standard value. Baud must be a whole number between 977 and
153800. Due to rounding, error increases with baud rate, actual baud must be within 3% of desired baud to ensure
accurate communication. Not available in I2C. Can be temporarily forced to 19200 by a manual override.
Speed Short Calculations shown below, standard crystal speed is 16MHz.
𝑆𝑝𝑒𝑒𝑑 =
𝐶𝑟𝑦𝑠𝑡𝑎𝑙𝑆𝑝𝑒𝑒𝑑
−1
(8 × 𝐷𝑒𝑠𝑖𝑟𝑒𝑑𝐵𝑎𝑢𝑑)
Equation 1: Speed Byte Calculation
𝐴𝑐𝑡𝑢𝑎𝑙𝐵𝑎𝑢𝑑 =
𝐶𝑟𝑦𝑠𝑡𝑎𝑙𝑆𝑝𝑒𝑒𝑑
(8 × (𝑆𝑝𝑒𝑒𝑑 + 1))
Equation 2: Actual Baud Rate Calculation
|𝐷𝑒𝑠𝑖𝑟𝑒𝑑𝐵𝑎𝑢𝑑 − 𝐴𝑐𝑡𝑢𝑎𝑙𝐵𝑎𝑢𝑑|
< 0.03
𝐷𝑒𝑠𝑖𝑟𝑒𝑑𝐵𝑎𝑢𝑑
Equation 3: Baud Rate Error Calculation
15
6.2 Text
2.1 Clear
Screen
Dec
254 88
Hex
FE 58
ASCII
■X
Clears the contents of the screen.
v5.6
2.2 Change the
Start Up Screen
Dec
254 64 Characters
v5.6
Hex
FE 40 Characters
ASCII
■ @ Characters
Changes the message displayed on start up. Custom characters can be included by adding their decimal value (07). Characters will automatically wrap on the display.
Characters
80 bytes, space characters can be added as needed
2.3 Auto
Scroll On
Dec
254 81
v5.6
Hex
FE 51
ASCII
■Q
The entire contents of screen are shifted up one line when the end of the screen is reached. Display default is on.
2.4 Auto
Scroll Off
Dec
254 82
v5.6
Hex
FE 52
ASCII
■R
New text is written over the top line when the end of the screen is reached. Display default is Auto Scroll on.
2.5 Set Auto
Line Wrap On
Dec
254 67
Hex
FE 43
ASCII
■C
Text will wrap to the next consecutive line once a row becomes full. Default is Auto Line Wrap on.
v5.6
2.6 Set Auto
Line Wrap Off
Dec
254 68
v5.6
Hex
FE 44
ASCII
■D
Text will skip one line when wrapping once a row becomes full. Writing order will be rows 1, 3, 2, and then 4.
Default is Auto Line Wrap on.
2.7 Set Cursor
Position
Dec
254 71 Column Row
Hex
FE 47 Column Row
ASCII
■ G Column Row
Sets the cursor to a specific cursor position where the next transmitted character is printed.
Column Byte Value between 1 and number of character columns.
Row
Byte Value between 1 and number of character rows.
v5.6
16
2.8 Go
Home
Dec
254 72
Hex
FE 48
ASCII
■H
Returns the cursor to the top left of the screen.
v5.6
2.9 Move
Cursor Back
Dec
254 76
Hex
FE 4C
ASCII
■L
Moves cursor one position to the left. Cursor will obey wrap settings.
v5.6
2.10 Move
Cursor Forward
Dec
254 77
Hex
FE 4D
ASCII
■M
Moves cursor one position to the right. Cursor will obey wrap settings.
v5.6
2.11 Underline
Cursor On
Dec
254 74
Hex
FE 4A
ASCII
■J
Displays a line under the current cursor position. Can be used with block cursor.
v5.6
2.12 Underline
Cursor Off
Dec
254 75
Hex
FE 4B
ASCII
■K
Removes line under current cursor position.
v5.6
2.13 Blinking
Block Cursor On
Dec
254 83
Hex
FE 53
ASCII
■S
Displays a blinking block over the current cursor position. Can be used with underline.
v5.6
2.14 Blinking
Block Cursor Off
v5.6
Dec
254 84
Hex
FE 54
ASCII
■T
Removes blinking block over current cursor position.
17
6.3 Special Characters
3.1 Create a Custom
Character
Dec
254 78 ID Data
v5.6
Hex
FE 4E ID Data
ASCII
■ N ID Data
Creates a custom character. Each character is divided into 8 rows of 5 pixels; each data byte represents one row.
Each byte is padded by three zero bits followed by five bits representing each pixel state. A one represents an on
condition while a zero is off. Characters are lost when a new memory bank is loaded, unless they are saved.
ID
Byte
Character ID, value between 0 and 7.
Data Byte[8] Character pixel data as shown below.
Table 13: Custom Degree Character
Data[1] 000 p1 p2 p3 p4 p5 00001000 8
Data[2] 000 p1 p2 p3 p4 p5 00010100 20
Data[3] 000 p1 p2 p3 p4 p5 00001000 8
Data[4] 000 p1 p2 p3 p4 p5 00000011 3
Data[5] 000 p1 p2 p3 p4 p5 00000100 4
Data[6] 000 p1 p2 p3 p4 p5 00000100 4
Data[7] 000 p1 p2 p3 p4 p5 00000011 3
Data[8] 000 p1 p2 p3 p4 p5 00000000 0
3.2 Save Custom
Characters
Dec
254 193 Bank ID Data
v5.6
Hex
FE C1 Bank ID Data
ASCII
■ ñ Bank ID Data
Provides access to all memory banks to create and save custom characters, graph bars, and large digits. Any new
characters saved will overwrite the old, so care should be taken when writing to any bar or digit memory bank.
Bank structure is shown below.
Bank Byte
1 byte, memory bank ID, value between 0 and 4, as below.
ID
Byte
1 byte, value between 0 and 7.
Data Byte[8] 8 bytes, character pixel data as above.
Table 14: Custom Character Banks
0
Start-up Characters
3.3 Load Custom
Characters
1
Horizontal Bars
2
Vertical Bars
3
Medium Digits
4
Large Digits
Dec
254 192 Bank
Hex
FE C0 Bank
ASCII
■ └ Bank
Loads a bank of custom characters into memory for use. Must be issued before using a bank of characters.
Alternatively, an appropriate initialize command can be used.
Bank Byte Memory bank ID, value between 0 and 4, as above.
v5.6
18
3.4 Save Start Up Dec
254 194 ID Data
v5.6
Screen Custom
Hex
FE C2 ID Data
■ ┬ ID Data
Characters
ASCII
Saves a custom character to memory for the start up screen or repeated use. Start up characters are displayed by
sending their ID to the screen.
ID
Byte
Value between 0 and 7.
Data Byte[8] Character pixel data, see Custom Degree Character example.
3.5 Initialize
Medium Numbers
Dec
254 109
v5.6
Hex
FE 6D
ASCII
■m
Loads the medium number custom character bank into memory. Medium numbers must be initialized before use.
3.6 Place Medium
Numbers
Dec
254 111 Row Column Digit
v5.6
Hex
FE 6F Row Column Digit
ASCII
■ o Row Column Digit
Places a single medium decimal digit of 2 row height and 1 column width on the display at the position specified.
Medium numbers must be initialized before being placed.
Row
Byte Value between 1 and 20.
Column Byte Value between 1 and 4.
Digit
Byte Single decimal digit to display.
3.7 Initialize
Horizontal Bar
Dec
254 104
v5.6
Hex
FE 68
ASCII
■h
Loads the horizontal bar graph custom character bank into memory. Horizontal bar characters must be initialized
before a graph is displayed.
3.8 Place Horizontal
Bar Graph
Dec
254 124 Column Row Direction Length
v5.6
Hex
FE 7C Column Row Direction Length
■ | Column Row Direction Length
ASCII
Places a horizontal bar graph on the screen beginning at the column and row specified. The bar extends either
right or left to the length indicated. New bars will overwrite old.
Column
Byte 1 byte, value between 1 and 20
Row
Byte 1 byte, value between 1 and 4
Direction Byte 1 byte, 0 for right and 1 for left
Length
Byte 1 byte, length in pixels of the graph, value between 0 and 100
3.9 Initialize Narrow
Vertical Bar
Dec
254 115
Hex
FE 73
ASCII
■s
Loads the narrow horizontal bar graph custom character bank into memory. A narrow bar is 2 pixels wide.
Horizontal bar characters must be initialized before a graph is displayed.
19
v5.6
3.10 Initialize Wide
Vertical Bar
Dec
254 118
v5.6
Hex
FE 76
ASCII
■v
Loads the wide horizontal bar graph custom character bank into memory. A wide bar is 5 pixels wide. Horizontal
bar characters must be initialized before a graph is displayed.
3.11 Place
Vertical Bar
Dec
254 61 Column Length
v5.6
Hex
FE 3D Column Length
ASCII
■ = Column Length
Places a vertical bar graph on the screen extending from the first row of the column specified. The bar extends
upwards to the length indicated. A new bar will over write the old.
Column
Byte
Value between 1 and 20.
Length
Byte
Height in pixels of the graph, value between 0 and 32.
6.4 General Purpose Output
4.1 General Purpose
Output On
Dec
254 87 Number
Hex
FE 57 Number
ASCII
■ W Number
Turns the specified GPO on, sourcing current from an output of five volts.
Number Byte GPO to be turned on.
v5.6
4.2 General Purpose
Output Off
v5.6
Dec
254 86 Number
Hex
FE 56 Number
ASCII
■ V Number
Turns the specified GPO off, sinking current to an output of zero volts.
Number Byte GPO to be turned off.
4.3 Set Start Up
GPO State
Dec
254 195 Number State
v5.6
Hex
FE C3 Number State
■ ├ Number State
ASCII
Sets and saves the start up state of the specified GPO in non volatile memory. Changes will be seen on start up.
Number Byte GPO to be controlled.
State
Byte 1 for on or 0 for off.
20
6.5 Dallas One-Wire
5.1 Search for a
One-Wire Device
Dec
254 200 2
v5.6
Hex
FE C8 02
■ ╚ SOT
ASCII
Sends a search query to each of the up to 32 devices on the one wire bus. Any connected device will respond with
an identification packet.
Response Bytes [14]
Dallas One-Wire identification packet as shown below.
Table 15: Dallas One-Wire Packet Information
Offset
0
Length
2
2
1
3
4
5
13
1
1
8
1
Value
9002
138
10
49
0
0
Description
Preamble
Another device packet will follow OR
Last device packet
Packet Type
Error Code (0 indicates success)
Device Address
CRC8 address check (0 indicates validity)
5.2 Dallas One-Wire
Transaction
Dec
254 200 1 Flags Send Bits Receive Bits Data
v5.6
Hex
FE C8 01 Flags Send Bits Receive Bits Data
■ ╚ STX Flags Send Bits Receive Bits Data
ASCII
Performs a single Dallas 1-Wire transaction. Consult your device documentation for information regarding device
specific protocols. If an error is encountered, a corresponding value will be returned by the device.
Flags
Byte
Flags for transaction, see below.
Send Bits
Byte
Number of bytes to be sent to the device.
Receive Bits Byte
Number of bytes expected to be received from the device.
Data
Byte(s) Data to be transmitted LSB to MSB.
Table 16: Dallas One-Wire Flags
Bit
7
6
5
4
3
2
1
0
21
Flag Description
Unused
0 (Future Compatibility)
Add CRC8 to transaction
0 (Future Compatibility)
Read CRC8 from transaction
Reset Bus prior to transaction
Table 17: Dallas One-Wire Errors
Code
0
1
2
3
Error Description
Success
Unknown Command
No Devices Found
Fatal Search Error
6.6 Keypad
6.1 Auto Transmit
Key Presses On
Dec
254 65
Hex
FE 41
ASCII
■A
Key presses are automatically sent to the host when received by the display. Default is Auto Transmit on.
v5.6
6.2 Auto Transmit
Key Presses Off
Dec
254 79
v5.6
Hex
FE 4F
ASCII
■O
Key presses are held in the 10 key buffer to be polled by the host using the Poll Key Press command. Use this
mode for I2C transactions. Default is Auto Transmit on.
6.3 Poll Key
Press
Dec
254 38
v5.6
Hex
FE 26
ASCII
■&
Reads the last unread key press from the 10 key display buffer. If another key is stored in the buffer the MSB will
be 1, the MSB will be 0 when the last key press is read. If there are no stored key presses a value of 0 will be
returned. Auto transmit key presses must be turned off for this command to be successful.
Response Byte Value of key pressed (MSb determines additional keys to be read).
6.4 Clear Key
Buffer
Dec
254 69
Hex
FE 45
ASCII
■E
Clears all key presses from the key buffer.
v5.6
6.5 Set Debounce
Time
Dec
254 85 Time
v5.6
Hex
FE 55 Time
ASCII
■ U Time
Sets the time between a key press and a key read by the display. Most switches will bounce when pressed; the
debounce time allows the switch to settle for an accurate read. Default is 8 representing approximately 52ms.
Time Byte Debounce increment (debounce time = Time * 6.554ms).
6.6 Set Auto
Repeat Mode
Dec
254 126 Mode
v5.6
Hex
FE 7E Mode
■ DEL Mode
ASCII
Sets key press repeat mode to typematic or hold. In typematic mode if a key press is held, the key value is
transmitted immediately, then 5 times a second after a 1 second delay. In hold mode, the key down value is
transmitted once when pressed, and then the key up value is sent when the key is released. Default is typematic.
Mode Byte 1 for hold mode or 0 for typematic.
22
6.7 Auto Repeat
Mode Off
Dec
254 96
Hex
FE 60
■`
ASCII
Turns auto repeat mode off. Default is on (typematic).
v5.6
6.8 Assign Keypad
Codes
Dec
254 213 Key Down Key Up
v5.6
Hex
FE D5 Key Down Key Up
■ ╒ Key Down Key Up
ASCII
Assigns the key down and key up values sent to the host when a key press is detected. A key up and key down
value must be sent for every key, a value of 255 will leave the key unaltered. Defaults are shown below.
Key Down Bytes [25]
Key down values, beginning at row one column one moving right then down.
Key Up
Bytes [25]
Key up values, beginning at row one column one moving right then down.
Table 18: Default Key Down Values
A(65)
F(70)
K(75)
P(80)
U(85)
B(66)
G(71)
L(76)
Q(81)
V(86)
Key Down
C(67)
H(72)
M(77)
R(82)
W(87)
D(68)
I(73)
N(78)
S(83)
X(88)
E(69)
J(74)
O(79)
T(84)
Y(89)
Table 19: Default Key Up Values
a(97)
f(102)
k(107)
p(112)
u(117)
b(98)
g(103)
l(108)
q(113)
v(118)
Key Up
c(99)
h(104)
m(109)
r(114)
w(119)
d(100)
i(105)
n(110)
s(115)
x(120)
e(101)
j(106)
o(111)
t(116)
y(121)
6.7 Display Functions
7.1 Backlight
On
Dec
254 66 Minutes
v5.6
Hex
FE 42 Minutes
ASCII
■ B Minutes
Turns the display backlight on for a specified length of time. If an inverse display color is used this command will
essentially turn on the text.
Minutes Byte Number of minutes to leave backlight on, a value of 0 leaves the display on indefinitely.
7.2 Backlight
Off
Dec
254 70
Hex
FE 46
ASCII
■F
Turns the display backlight off. If an inverse display colour is used this command will turn off the text.
23
v5.6
7.3 Set VFD
Brightness
Dec
254 89 Brightness
Hex
FE 59 Brightness
ASCII
■ Y Brightness
Immediately sets the text brightness. Default is 0.
Brightness Byte
Brightness level from 3(Dim) to 0(Bright)
v5.6
7.4 Set and Save
VFD Brightness
Dec
254 145 Brightness
v5.6
Hex
FE 91 Brightness
■ æ Brightness
ASCII
Immediately sets and saves the text brightness. Although brightness can be changed using the set command, it is
reset to the saved value on start up. Default is 0.
Brightness Byte
Brightness level from 3(Dim) to 0(Bright)
6.8 Data Security
8.1 Set
Remember
Dec
254 147 Switch
v5.6
Hex
FE 93 Switch
ASCII
■ ô Switch
Allows changes to specific settings to be saved to the display memory. Writing to non-volatile memory can be slow
and each change consumes 1 write of at least 100,000 available. The Command Summary outlines which
commands are saved always, never, and when this command is on only. Remember is off by default.
Switch Byte 1 for on or 0 for off.
8.2 Set Data
Lock
Dec
254 202 245 160 Level
v5.6
Hex
FE CA F5 A0 Level
ASCII
■ ╩ ⌡ á Level
Temporarily locks certain aspects of the display to ensure no inadvertent changes are made. The lock is released
after a power cycle. A new level overrides the old, and levels can be combined. Default is 0.
Level Byte Lock level, see Data Lock Bits table.
Table 20: Data Lock Bits
Display
7
Command
6
Reserved
5
Setting
4
Address
3
Reserved
2
Reserved
1
Reserved
0
Table 21: Lock Parameters
Reserved
Address
Setting
Command
Display
Place holders only, should be 0
Locks the Baud Rate and I2C address
Locks all settings from being saved
Locks all commands, text can still be written
Locks entire display, no new text can be displayed
24
8.3 Set and Save
Data Lock
Dec
254 203 245 160 Level
v5.6
Hex
FE CB F5 A0 Level
ASCII
■ ╦ ⌡ á Level
Locks certain aspects of the display to ensure no inadvertent changes are made. The lock is not affected by a
power cycle. A new level overrides the old, and levels can be combined. Default is 0.
Level Byte
See Data Lock Bits table.
6.9 Miscellaneous
9.1 Write
Customer Data
Dec
254 52 Data
v5.6
Hex
FE 34 Data
ASCII
■ 4 Data
Saves a user defined block of data to non-volatile memory. Useful for storing display information for later use.
Data Byte [16] User defined data.
9.2 Read
Customer Data
Dec
254 53
v5.6
Hex
FE 35
ASCII
■5
Reads data previously written to non-volatile memory. Data is only changed when written, surviving power cycles.
Response
Byte [16]
Previously saved user defined data.
9.3 Read Version
Number
Dec
254 54
Hex
FE 36
ASCII
■6
Causes display to respond with its firmware version number. Test.
Response
Byte
Convert to hexadecimal to view major and minor revision numbers.
v5.6
9.4 Read
Module Type
v5.6
Dec
254 55
Hex
FE 37
ASCII
■7
Causes display to respond with its module number.
Response Byte Module number, see Sample Module Type Responses for a partial list.
Table 22: Sample Module Type Responses
14
86
25
VK202-25
VK202-25-USB
7 Appendix
7.1 Command Summary
Available commands below include identifying number, required parameters, the returned response and
an indication of whether settings are remembered always, never, or with remember set to on.
Table 23: Communication Command Summary
Name
Change Baud Rate
2
Change I C Slave Address
Transmission Protocol Select
Set a Non-Standard Baud Rate
Dec
57
51
160
164
Hex
39
33
A0
A4
ASCII
9
3
á
ñ
Parameters
Byte
Byte
Byte
Short
Response
None
None
None
None
Remembered
Always
Always
Remember On
Always
Table 24: Text Command Summary
Name
Clear Screen
Change the Start Up Screen
Auto Scroll On
Auto Scroll Off
Set Auto Line Wrap On
Set Auto Line Wrap Off
Set Cursor Position
Go Home
Move Cursor Back
Move Cursor Forward
Underline Cursor On
Underline Cursor Off
Blinking Block Cursor On
Blinking Block Cursor Off
Dec
88
64
81
82
67
68
71
72
76
77
74
75
83
84
Hex
58
40
51
52
43
44
47
48
4C
4D
4A
4B
53
54
ASCII
X
@
Q
R
C
D
G
H
L
M
J
K
S
T
Parameters
None
Byte[]
None
None
None
None
Byte[2]
None
None
None
None
None
None
None
Response
None
None
None
None
None
None
None
None
None
None
None
None
None
None
Remembered
Never
Always
Remember On
Remember On
Remember On
Remember On
Never
Never
Never
Never
Remember On
Remember On
Remember On
Remember On
26
Table 25: Special Character Command Summary
Name
Create a Custom Character
Save Custom Characters
Load Custom Characters
Save Start Up Screen Custom
Characters
Initialize Medium Numbers
Place Medium Numbers
Initialize Horizontal Bar
Place Horizontal Bar Graph
Initialize Narrow Vertical Bar
Initialize Wide Vertical Bar
Place Vertical Bar
Dec
78
193
192
Hex
4E
C1
C0
ASCII
N
ñ
└
Parameters
Byte[9]
Byte[10]
Byte
Response
None
None
None
Remembered
Remember On
Always
Never
194
C2
┬
Byte[9]
None
Always
109
111
104
124
115
118
61
6D
6F
68
7C
73
76
3D
m
o
h
|
s
v
=
None
Row, Col, Digit
None
Col, Row, Dir, Length
None
None
Col, Length
None
None
None
None
None
None
None
Never
Never
Never
Never
Never
Never
Never
Table 26: General Purpose Output Command Summary
Name
General Purpose Output On
General Purpose Output Off
Set Start Up GPO State
Dec
86
87
195
Hex
56
57
C3
ASCII
V
W
├
Parameters
Byte
Byte
Byte[2]
Response
None
None
None
Remembered
Never
Never
Always
Table 27: Dallas One-Wire Command Summary
Name
Search for a One-Wire Device
Dallas One-Wire Transaction
Dec
200, 2
200, 1
Hex
C8, 02
C8, 01
ASCII
╚, SOT
╚, STX
Parameters
None
Byte[3], Byte[]
Response
Byte[14]
Byte[]
Remembered
Never
Never
Response
None
None
Byte
None
None
None
None
None
Remembered
Remember On
Remember On
Never
Never
Remember On
Remember On
Remember On
Always
Table 28: Keypad Command Summary
Name
Auto Transmit Key Presses On
Auto Transmit Key Presses Off
Poll Key Press
Clear Key Buffer
Set Debounce Time
Set Auto Repeat Mode
Auto Repeat Mode Off
Assign Keypad Codes
27
Dec
65
79
38
69
85
126
96
213
Hex
41
4F
26
45
55
7E
60
D5
ASCII
A
`
&
E
U
DEL
`
╒
Parameters
None
None
None
None
Byte
Mode
None
Byte[25], Byte[25]
Table 29: Display Functions Command Summary
Name
Backlight On
Backlight Off
Set VFD Brightness
Set and Save VFD Brightness
Dec
66
70
89
145
Hex
42
46
59
91
ASCII
B
F
Y
æ
Parameters
Byte
None
Byte
Byte
Response
None
None
None
None
Remembered
Remember On
Remember On
Remember On
Always
Table 30: Data Security Command Summary
Name
Set Remember
Set Data Lock
Set and Save Data Lock
Dec
147
202, 245, 160
203, 245, 160
Hex
93
CA, F5, A0
CB, F5, A0
ASCII
ô
╩, ⌡, á
╦, ⌡, á
Parameters
Byte
Byte
Byte
Response
None
None
None
Remembered
Always
Remember On
Always
Table 31: Miscellaneous Command Summary
Name
Write Customer Data
Read Customer Data
Read Version Number
Read Module Type
Dec
52
53
54
55
Hex
34
35
36
37
ASCII
4
5
6
7
Parameters
Byte[16]
None
None
None
Response
None
Byte[16]
Byte
Byte
Remembered
Always
Never
Never
Never
28
7.2 Character Sets
Figure 16: VFD Model Japanese Character Set
29
7.3 Block Diagram
Figure 17: Functional Diagram
7.4 Environmental Specifications
Table 32: Environmental Limits
VFD Standard VFD Extended (-E)
-20°C to +70°C
-40°C to +85°C
-40°C to +85°C
-50°C to +85°C
Maximum 80% non-condensing
Maximum 10°C /min
Operating Temperature
Storage Temperature
Operating Relative Humidity
Thermal Shock
7.5 Electrical Tolerances
Current Consumption
Table 33: Current Consumption
Board
40mA
+
Backlight
170 mA
+
GPOs
20mA each maximum
Table 34: Backlight Current Draw
VFD
170mA
Input Voltage Specifications
Table 35: Voltage Specifications
Standard
4.75-5.25V
Wide Voltage (-V)
9.0-15.0V
30
7.6 Dimensional Drawings
Figure 18: VK202-25 Dimensional Drawing
Figure 19: VK202-25-USB Dimensional Drawing
31
7.7 Optical Characteristics
Table 36: Display Optics
Module Size
Viewing Area
Active Area
Character Size
Character Pitch
Pixel Size
Pixel Pitch
VFD Brightness
VFD Model
116.00 x 37.00 x 29.0
96.0 x 24.0
70.8 x 11.6
2.40 x 4.70
3.60 x 6.10
0.40 x 0.50
0.50 x 0.70
350
mm
mm
mm
mm
mm
mm
mm
cd/m2
8 Ordering
8.1 Part Numbering Scheme
Table 37: Part Numbering Scheme
VK
1
-202
2
-25
3
-FW
4
-V
5
6
-E
7
8.2 Options
Table 38: Display Options
#
Designator
1
Product Type
2
3
4
Display Size
Keypad Size
Colour
5
Voltage
6
Protocol
7
Temperature
Options
LK: Liquid Crystal Display with Keypad Input
OK: Organic Light Emitting Display with Keypad Input
VK: Vacuum Florescent Display with Keypad Input
-202: 20 columns by 2 rows
25: 25 key maximum
*NP: Standard (No filter for VFD)
*NP: Standard Voltage
-V: Wide Voltage
*NP: Standard Model
-USB: USB Only Model
*NP: Standard
-E: Extended Temperature
*Note: NP means No Populate; skip this designator in the part number and move to the next option.
32
8.3 Accessories
Power
Table 39: Power Accessories
PCS
Standard Power Cable
Communication
Table 40: Communication Accessories
33
CSS1FT
1 ft. Serial Cable
CSS4FT
4 ft. Serial Cable
EXTMUSB3FT
Mini-USB Cable
INTMUSB3FT
Internal Mini-USB Cable
SCCPC5V
Serial Communication/5V Power
Cable
BBC
Breadboard Cable
Peripherals
Table 41: Peripheral Accessories
KPP4x4
16 Button Keypad
KPP20A-XX*
7 Button Keypad Overlay
Temperature Probe
Dallas One-Wire Temperature Probe
Mounting
Table 42: Mounting Accessories
B2041-XX**
Mounting Bracket with Coloured
Overlay
B204A-XX*
Mounting Bracket with Keyed
Overlay
MK2041-XX**
Coloured Overlay with Drill Guide
*Note: Keyed overlays are available in Black (-BK), Silver (-SK), Red (-DR), and Beige(no part extension) Vinyl.
**Note: Non-keyed overlays are available in Black Vinyl (-BK), Black Brushed Aluminum (-BL), Silver Brushed
Aluminum (-AL), and Beige Vinyl (no part extension).
34
9 Definitions
ASCII: American standard code for information interchange used to give standardized numeric codes
to alphanumeric characters.
BPS:
Bits per second, a measure of transmission speed.
DOW: Dallas One-Wire protocol, similar to I2C, provides reduced data rates at a greater distance. One
wire carries data, while two others supply power and ground. Matrix Orbital tests non-parasitic devices
only, those that do not draw power from the data line; however, some parasitic devices may work.
FFSTN: Double film super-twisted nematic in reference to an LCD. The addition of two layers of film
between the STN display and polarizer improves contrast.
GPO:
General purpose output, used to control peripheral devices from a display.
GUI:
Graphical user interface.
Hexadecimal:
A base 16 number system utilizing symbols 0 through F to represent the values 0-15.
I2C:
Inter-integrated circuit protocol uses clock and data lines to communicate short distances at
slow speeds from a master to up to 128 addressable slave devices. A display is a slave device.
LSB:
Least significant bit or byte in a transmission, the rightmost when read.
MSB:
Most significant bit or byte in a transmission, the leftmost when read.
RS232: Recommended standard 232, a common serial protocol. A low level is -30V, a high is +30V.
SDA: Serial data line used to transfer data in I2C protocol. This open drain line should be pulled high
through a resistor. Nominal values are between 1K and 10K Ω.
SCL:
Serial clock line used to designate data bits in I2C protocol. This open drain line should be pulled
high through a resistor. Nominal values are between 1K and 10K Ω.
STN: Super-twisted nematic in reference to an LCD. In a relaxed or nematic state, crystals orientate
themselves in the same direction and allow light to pass. In an excited state these crystals align to block
light. Super-twisted crystals move from 180 to 270 degrees providing greater contrast than TN models.
TTL:
Transistor-transistor logic applied to serial protocol. Low level is 0V while high logic is 5V.
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