Matrix Orbital GLK12232-25-SM - Manual (Page 41)

10.1.1 I 2 C Interface
The keypad is read by I 2 C master read. In short, this means that a read of the module will always return
the first unread key press. A read is initiated by writing to the module with its base address plus 1, then
clocking the module’s return byte after the module releases the SDA line. Much more detail on this basic
I
2 C function can be found in the I 2 C specification by Phillips.
10.1.2 RS232 Interface
By default on any press of a key, the module will immediately send out the key code at the selected baud
rate. This behavior can be modified using commands found in the next section.
10.2 Auto Transmit Key Presses On
Syntax Hexadecimal 0xFE 0x41
Decimal 254 65
ASCII 254 “A”
Description In this mode, all key presses are sent immediately to the host system
without the use of the poll keypad command. This is the default mode
on power up.
NOTE This command is not available in I 2 C.
Remembered Yes
Default On
10.3 Auto Transmit Key Presses Off
Syntax Hexadecimal 0xFE 0x4F
Decimal 254 79
ASCII 254 “O”
Description In this mode, up to 10 key presses are buffered until the unit is polled by
the host system, via the poll keypad command 254 38. Issuing this
command places the unit in polled mode.
NOTE This command is not available in I 2 C.
Remembered Yes
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