Matrix Orbital GLK12232-25-SM Legacy - Manual (Page 19)

19
5. Keypad Interface
This chapter describes the keypad interface and associated commands in detail.
5.1 General
The GLK12232-25-SM keypad interface processes the keypad row/column matrix into a serial (RS-232 or
I
2 C) data byte stream. Aside from this processing, the keypad has no effect on the GLK12232-25-SM
display. If you need to send keystrokes to the display, they must be routed through your controller.
5.2 Connections
Figure 5-1 Keypad Connector
The connector is not "keyed" so your keypad will probably plug in either of two ways. The GLK12232-25-
SM will not be damaged by reversing the connector, but your keypad will generate a different ASCII
character mapping for each position. If your connector has fewer than 10 pins it should probably be
centered on the GLK12232-25-SM connector.
The returned key codes are as follows, but note that your keypad may be laid out in a different pattern. If
this is the case, you will need to interpret the key codes differently. The diagram 1 shows the logical layout
(row 1, column 1 in upper left). The connector for the keypad is a 10 pin 0.1" spacing male header. Pin 1 is
indicated in
Figure 2-1. Pins 1 through 5 are columns and pins 6 through 10 are rows. The keypad is scanned whenever
a key is pressed: there is no continuous key scan. This means that key presses are dealt with immediately
without any appreciable latency. This also prevents electrical noise which is often caused by continuous key
scans.