12 Filesystem
12.1 Introduction
The GLK12232-25-SM incorporates a 16 Kbyte on board ?ash mem
ory in order to allow up to 128 font
and bitmap ?les to be transfered directly onto the display an
d recalled whenever necessary. The ?lesystem
can address font and bitmap ?les combined up to 16 Kbytes. It i
s recommended that fonts and bitmaps
are uploaded when possible all together after a ?lesystem wi
pe 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 ?les, as well as getting the remaining sp
ace or wiping the ?lesystem.
12.1.1 File Upload Protocol
In order to allow fonts and bitmaps to be uploaded to the on board ?ash memory Matrix Orbital has
developed a simple protocol that supports RS-232/TTL or I2C communications. In order to begin a ?le
transmission the ?rst step will be to provide the display mod
ule with the appropriate command bytes, mean-
ing the command pre?x, 0xFE, followed by the command number,
0x24 for a font ?le, or 0x5E for a bitmap
?le. This will begin the ?le transfer sequence. The next step
will be to request a reference identi?cation
number (ref ID) which will allow you to identify the ?le for fu
ture 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 ?le is to provide the display
module with the two byte ?le size of the
data that you wish to transfer, LSB to MSB. The LSB must be transmitted ?rst followed by the MSB. After
receiving the MSB the display module will send a con?rm byte,
0x01, if the ?le ?ts and continue, or decline
byte, 0x08, and terminate the session.
Byte
Description
0x01
Con?rm: Will continue the ?le transfer.
0x08
Decline: Terminate the session.
The last part of uploading a font ?le is to upload the ?le data.
After transmitting each byte of the ?le the
module will echo the byte and wait for a con?rmation byte of 0x
01 until the ?le has completed uploading.
Below is an example of uploading the font ?le which we created
in
Section 5.1.2 on page 20.
At times that the display or the host sees anything else otherthan 0x01 for con?rmation (usually a 0x08)
the upload is aborted.
Matrix Orbital GLK12232-25-SM
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