Description This command setsthe display’scontrast to [contrast], where[contrast] is
a value between 0x00 and 0xFF (between 0 to 255). Lower values cause
‘on’ elements in the display area to appear lighter, while higher values
cause ‘on’ elements to appear darker. Lighting conditions will affect the
actual value used for optimal viewing. Individual display modules will
also differ slightly from each other in appearance. In addition, values for
optimal viewing while the display backlight is on may differ from values
used when backlight is off.
NOTE This command saves the [contrast] value so that it is not lost after power down.
Remembered Yes
Factory Default 128
11 Filesystem
11.1 Introduction
11.1.1 File Upload Protocol
In order to allow fonts and bitmaps to be uploaded to the on board flash memory Matrix Orbital has
developed a simple protocol that supports RS-232/TTL or I
2
C communications. In order to upload a font
file you must first provide a reference identification number (ref ID), then the file size and finally the data.
The reference identification number will allow you to identify the font for future use. After transmitting
the refID, please wait for the display module to send an immediate confirmation that the reference ID has
not been used yet. The display module will do this in the form of echoing the byte back to you. Once you
receive the echo, you must then confirm it by sending a 0x01 byte.
The next part of uploading a font file is to provide the display module with a two byte file size of the
font file you are attempting to upload; the font size must be formated LSB to MSB. After the first byte is
transmitted you will receive an echo of the byte and you must confirm the echo with a confirmation byte
(0x01). However, after the display module receives the second byte it will echo the byte and then send a
0x01 confirmation byte if the file fits, if the file does not fit the module will notify you by sending 0x08 and
then it will terminate the upload session. If the font file does fit you must confirm the echo with a 0x01 byte.
Matrix Orbital GLK24064-25 43
