Matrix Orbital LK202-25 Legacy User Manual

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Whether the user is in ‘Buffer Return Status Mode’ or not, the module will ignore display or command bytes which would
overrun the buffer. While in ‘Buffer Return Status Mode’ the unit will return 0xFE when buffer is almost full even though it
may have already thrown rejected data away.

When using this command in an application, selection of the value for the buffer almost full should be considered very
carefully. This is a critical aspect of using this command to it’s full potential. When using a host system or PC which
contains a FIFO, the user should set the value of equal to or greater than the size of the FIFO. The reason for this is that the
FIFO may be full when the host system receives 0xFE. In the case of 16550 UART the size at its maximum is 16, therefore
the value of should be set to 16 or greater.

Exit Buffer Return Status Mode
ASCII ‘;’, Hex 3B, Decimal 59
Syntax 0xFE 0x3B

The command allows the user exit buffer return status mode.

Backlight On
ASCII 'B', Hex 42, Decimal 66
Syntax 0xFE 0x42

To turn the backlight on, send a command prefix followed by the character 'B' and the number of minutes for the backlight
to remain on. If is sent as zero then the backlight will remain on indefinitely. The maximum value for utes> is 100. Example:

0xFE

0x42

0 to 100

Backlight Off
ASCII 'F', Hex 46, Decimal 70
Syntax 0xFE 0x46

To turn the backlight off, send a command prefix followed by the character 'F'.

Clear Display
ASCII 'X', Hex 58, Decimal 88
Syntax 0xFE 0x58

This command clears any text and graphics off the display. To clear the display, send a command prefix followed the
character 'X'.

Clear Key Buffer
ASCII 'E', Hex 45, Decimal 69
Syntax 0xFE 0x45

This command clears any unread keypresses. In a menuing application, if the user presses a key which changes the menu
context, any following key presses may be inaccurate and can be cleared out of the buffer between menu changes to prevent
jumping around the menu tree. It may also be used to, in effect, reset the keypad in case the application resets for whatever
reason. To execute this command, send a command prefix followed by the character 'E'.