8-1
Section 8
KEYPAD BOARD INFORMATION
1.0
Theory of Operation
Keypad
U602 is a comparator that will compare the voltage when any one of the keypad row or keypad
column keys is being pressed. Therefore when a key is being pressed, it will send a message to the
microprocessor through the output (KEY_INT) telling it that a key has been pressed. The
microprocessor will then sample the Analog to Digital voltages at the keypad row and keypad
column and map it with the table so that the key being pressed can be identified.
2.0
Troubleshooting Chart
Figure 8-2 Keypad Board Troubleshooting Chart
Figure 8-1 Keypad Block Diagram
40 pin connector
Comparator
Keypad
Button
9 pin connector
Key_Int
Keypad Column
Keypad
Data
Row
Tone
End
Disconnect and
reconnect 40-pin
flex
No
Yes
Press Keypad
Summary of Contents for GP88s
Page 1: ...November 2003 GP88s Portable Radio Service Manual 6804111J47 D ...
Page 4: ...iv Document History THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 16: ...xvi 4 0 Parts List for Speaker Mic Assembly 0104008J99 10 2 Glossary of Terms G 1 ...
Page 28: ...3 6 Programming Test Cable THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 52: ...5 6 Test Mode THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 56: ...6 4 Cloning Information THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 60: ...7 4 Controller Board THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 180: ...9B 48 Circuit Board Schematic Diagrams and Parts List THIS PAGE INTENTIONALLY LEFT BLANK ...