Matrix Orbital GLK12232-25-SM Legacy - Manual (Page 8)

1.8 Trying out a Keypad
Since a number of different keypad types can be connected to the display, the results may be a little
unpredictable. At this point all we need to do is make sure that the keypad and interface work, and possibly
generate an ASCII map for any programming needs.
The keypad interface on the display converts a row / column connection to an ASCII character. By
default, a keypress is transmitted as serial data immediately. Keypad buffering can be selected using the
appropriate commands.
1.8.1 Here’s what to do:
1. The PC should be running a terminal program such as Hyperterm.
2. With the display connected to the PC, plug in the keypad. If the connector has fewer pins than the one
on the display, center it as well as possible.
NOTES
• The keypad connector must be wired with columns on one side and rows on the other
side of the center of the connector. If the keypad isn’t wired this way, an adapter will
need to be made. Another method would be to rewire the connector to meet this
requirement.
• The connector is reversible. Reversing the connector will not damage the keypad or
the display, but will however, change the ASCII character map.
3. Press a key on the keypad. An upper case ASCII character (A-Y) should appear on the PC screen.
Different keys should generate different characters.
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.
1.9 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
Matrix Orbital GLK12232-25-SM 4