Matrix Orbital GLK24064-25 Legacy - Manual (Page 17)

GLK24064-25 rev. 06 17
Up to 7 strip charts ([ref] = 0 – 6) may be defined. To initialize a strip chart the user must define an area on
the display in which to place the strip chart.(x
1
,y
1
) is the top left corner of the area to be used, where [x
1
] is
the placement of the column where the strip chart is to begin and [y
1
] is the row. The user must then define
[x
2
] as the bottom right column of the area to be utilized and [y
2
] as the bottom right row.
The definition of x must lie on "byte boundaries". That is, x must be defined as 0x00, 0x08, 0x10, etc. This
restriction does not apply to y values.
4.2.12 Shift strip chart (254 107 [ref])
This command shifts the strip chart left or right. [ref] determines both which strip chart is used and which
direction it will shift. The direction is selected by the most significant bit (MSB):
MSB = 0 shifts left
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 GLK24064-25 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 (see Table 8-5 and the next two
sections). If flow control is enabled, the GLK24064-25 will return an "almost full" message (0xFE) to the
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
GLK24064-25 will return an "almost full" message (0xFE) to the controller. When the buffer empties so
that only [empty] bytes remain the GLK24064-25 will return an "almost empty" message (0xFF) to the
controller.
The GLK24064-25 will return the "almost full" message for every byte sent to the GLK24064-25 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 overrun the buffer. While in ‘Flow Control Mode’ the unit will return 0xFE when buffer is almost
full even though it may have already thrown rejected data away. The buffer size for the GLK24064-25 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 [full] 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.