Similarly, in order to change the display to TTL mode, simply remove the zero ohm resistors from the 232
or I
2
C jumpers and solder them to the TTL jumpers.
Figure 16: Protocol Select Jumpers
2.4 Keypad Interface Connector
The GLK24064-25 provides a Keypad Interface Connector which allows for up to a five by five matrix
style keypad to be directly connected to the display module. Key presses are generated when a short is
detected between a row and a column. When a key press is generated a character, which is associated with
the particular key press, is automatically sent on the Tx communication line. If the display module is running
in I
2
C mode, the “Auto Transmit Keypress” function may be turned off, to allow the key presses to remain
in the buffer so that they may be polled. The character that is associated with each key press may also be
altered using the “Assign Key Codes” command, for more detailed information see the Keypad Section, on
page 35.
Figure 17: Keypad Interface Connector
Matrix Orbital GLK24064-25 11
