7 appendix: command summary, 1 general, 2 issuing commands – Matrix Orbital VK204-25 Legacy User Manual

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6.1.8 Read Version Number (254 54)

This command will return the firmware version number of the display. The command will return a 1-byte

hex value.

7 Appendix: Command Summary

7.1 General

The operation of the display is controlled by a simple and consistent command set. Commands control;

• Text display
• Graphics display
• Keypad interface
• Miscellaneous operating parameters

This chapter includes summary tables of all commands.

7.2 Issuing Commands

Commands are issued to the display by the controller. In a test setup, commands can be issued to

the display by means of a BASIC program, using the chr$( ) function. In the tables below, we’ve shown

commands in hex, ASCII and decimal form. All commands begin with the prefix character 0xFE (254

decimal). These commands are issued on the serial communications link (I

C or RS-232) at the currently

defined baud rate.

For example (using BASIC in a test setup), the user could issue the command to clear the screen on the

display by including the line;

CDFEHG£I¢PF(QR3H ¢S1TVUW2£'XFYa`R3$ £SbTcUWdd)Y

in the BASIC program.

Or, with C the user could (using Zcomm serial library)

e¥f¢gHB£Bh(7i7pq¢SF$¡1"f¢gB£B1r¢s¡¢"hUtvuwtxYa`

7.3 On Numbers

Like all computerized devices, the display operates with commands and values in the form of binary

numbers. These binary numbers are arranged in 8 digit (i.e., 8 bit) groups called bytes. The decimal value

of a byte may have any value from 0 to 255.

Bytes are usually specified in either decimal or hexadecimal (base 16) form for convenience, since binary

numbers are confusing to deal with directly. Hexadecimal (hex) numbers are particularly convenient because

Matrix Orbital

VK204-25