Matrix Orbital GLC24064 - Manual (Page 41)

10.8 Set and Save Contrast
Syntax Hexadecimal 0xFE 0x91 [contrast]
Decimal 254 145 [contrast]
Parameters Parameter Length Description
contrast 1 Contrast value (0 to 255).
Description This command sets the display’s contrast 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
Default 128
11 Filesystem
11.1 Introduction
The incorporates a 16 Kbyte on board flash memory in order to allow up to 128 font and bitmap files
to be transfered directly onto the display and recalled whenever necessary. The filesystem can address font
and bitmap files combined up to 16 Kbytes. It is recommended that fonts and bitmaps are uploaded when
possible all together after a filesystem wipe ro preserve memory integrity. These fonts and bitmaps can then
be locked to ensure they remain intact. This section covers uploading, downloading, deleting and moving
files, as well as getting the remaining space or wiping the filesystem.
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 begin a file
transmission the first step will be to provide the display module with the appropriate command bytes, mean-
ing the command prefix, 0xFE, followed by the command number, 0x24 for a font file, or 0x5E for a bitmap
file. This will begin the file transfer sequence. The next step will be to request a reference identification
number (ref ID) which will allow you to identify the file for future use. Reference ID numbers can be any
byte between 0x00 and 0x7F, however each ID must be unique.
The next part of uploading a font file is to provide the display module with the two byte file size of the
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