Matrix Orbital LK202-24-USB - Manual (Page 35)

8 Appendix: Command Summary
8.1 General
The operation of the display is controlled by a simple and consistent command set. Commands control;
• Text display
• Graphic display
• Keypad interface
• Miscellaneous operating parameters
This chapter includes summary tables of all commands.
8.2 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$() function. In the tables below, commands are shown
in hex, ASCII and decimal form. All commands begin with the prefix character 0xFE (254 decimal). These
commands are issued on the serial communications link USB, at the currently defined baud rate.
For example (using a BASIC setup), the user could issue the command to clear the screen on the display
by including the line;
PRINT#1,chr$(254);chr$(88)
Or, with C the user could (using Zcomm serial library);
ZComm1->WriteCommByte (0xfe) ;
ZComm1->WriteCommByte (’X’) ;
8.3 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
exactly two hexadecimal digits make up one byte, each hex digit representing 4 binary digits (4 bits) as shown
in the Table below.
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