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Protocol Select Jumpers
Figure 12: Protocol select Jumpers
The Protocol Select Jumpers provide the means necessary to toggle the GLK12232-25 between RS-232,
TTL and I²C protocols. As a default, the jumpers are set to RS-232 mode with solder jumps on the RS232
jumpers. In order to place the display module in I²C mode you must first remove the solder jumps from
the RS232 jumpers and then place them on the I
2
C jumpers. The display will now be in I²C mode and
have a default slave address of 80, unless changed with the appropriate command. Similarly, in order to
change the display to TTL mode, simply remove the zero ohm resistors from the RS232 or I²C jumpers
and solder them to the TTL jumpers. Protocol resistors should be set to TTL for USB, and cannot be
moved.
Hardware Lock
Figure 13: FileSystem Lock Jumper
The Hardware Lock allows fonts, bitmaps, and settings to be saved, unaltered by any commands. By
connecting the two pads near the memory chip with a zero ohm resistor, the display will be locked. This
supersedes the data lock command and cannot be circumvented by any software means. To unlock the
display and make changes simply remove the jumper.