MOBILE COMMUNICATIONS DIVISION
CUSTOMER SERVICES
Version 1.0 22/11/2006
Created by Konrad Szombara
Page 69 of 103
6.3 SWITCHES
6.3.1 KEYPAD
The keypad matrix contains 4 rows and 5 columns, allowing 20 keys to be
scanned. When a key is pressed, a keypad interrupt is generated. Then
system scans each column in turn and reads which row is active to
determine which key is pressed. Because of key bounce, the key press is
confirmed twice at approximately 40-60 ms intervals.
Figure Keypad Connections
6.3.2 POWER KEY
The two terminals of POWER key are connected to ground and
POWER_KEY pin of AD6537B. POWER_KEY pin is connected to high
voltage through internal resistor of AD6537B. When user presses the
POWER key, POWER_KEY pin is pulled low and a key interrupt is
generated. System will be booted-up unless key press longer than 2 seconds
to prevent user mis-pressing the POWER key.
Figure Power Key Connections
