Matrix Orbital GLK24064-25 Legacy - Manual (Page 8)

To experiment, reverse the connector and see if it generates a more logical set of characters. Ultimately, the
program in the micro-controller will have to ’map’ these characters to the ones marked on the keypad, which
will likely be different.
1.7 Manual Over-ride
Manual over-ride should only be required in one instance. If for some reason the module is set at a baud
rate which cannot be produced by the host system and all communication to the display is lost, then the user
should follow this simple procedure;
1. Turn off the display.
2. Put a jumper on pins 5 and 6 of the keypad connector.
3. Power up the display. The baud rate is now set to 19,200.
4. Remove the jumper and change the RS-232 port settings to the desired baud rate.
5. Turn off the display.
6. Power up the display.
Refer to the "Set RS-232 port speed" command for acceptable baud rates. This procedure does not change
settings in the memory chip, it uses default settings stored in the main processor. This allows the user to
communicate with the display when all other communications are lost. Once able to communicate with the
display, the user may then change the default settings in the memory chip.
Please note, with the manual over-ride jumper in place, the unit will receive and perform commands such
as turning on and off the backlight, but will not output text to the LCD.
1.8 Memory Chip Lock Down
The display uses a memory chip to store speed, startup screen contrast, fonts, bitmaps and I 2 C settings.
When everything has been changed to the desired settings and the unit is in a finished product or in the field,
locking down the memory chip so no settings can be changed becomes very useful. This is only to be done
by knowledgeable people. Any damage to the display by this procedure resulting from user error will not be
covered under the Manufacturer’s Warranty.
Figure 2: Lockdown
Matrix Orbital GLK24064-25 4