Matrix Orbital GLK24064-25 Legacy - Manual (Page 23)

MSB = 1 shifts right
For example, if [ref] is 1;
254 107 1 (hex FE 6B 01) shifts left
254 107 129 (hex FE 6B 81) shifts right
This command shifts the contents of the area defined in the "Initialize strip chart" command 8 pixels at a
time.
4.3 Flow Control
The display has built in flow control which is very useful during direct bitmap display and multiple pixel
placement. Flow control is enabled or disabled by two commands. If flow control is enabled, the display
will return an "almost full" message (0xFE) to the micro-controller when its internal buffer fills to a defined
level, and an "almost empty" message (0xFF) when the buffer contents drop to a defined level.
4.3.1 Enter Flow Control Mode (254 58 [full][empty])
NOTE Flow control applies only to the RS-232 interface. It is not available for I 2 C.
This command enables flow control. When the buffer fills so that only [full] bytes are available the display
will return an "almost full" message (0xFE) to the micro-controller. When the buffer empties so that only
[empty] bytes remain the display will return an "almost empty" message (0xFF) to the micro-controller.
The display will return the "almost full" message for every byte sent to the display until the used buffer
space once more drops below the [full] level.
Whether the user is in ’flow control mode’ or not, the module will ignore display or command bytes
which would over-run the buffer. While in ’flow control mode’ the unit will return 0xFE when the buffer is
almost full even though it may have already thrown rejected data away. The buffer size for the display is 96
bytes.
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.
WARNING This mode must not be used during loading of fonts and
bitmaps. It is highly recommended for use with direct screen write and
multiple pixel placements.
4.3.2 Exit Flow Control Mode (254 59)
This command turns off flow control. Bytes may overflow the buffer without warning.
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