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NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 1234 -
Revision V1.30
NUC97
0
T
E
CHNIC
A
L
RE
F
E
RE
N
CE
MA
NUA
L
the pins attached to the keypad columns. The nibble driven onto the rows always contains only a
single 0. The only way the microcontroller can find a 0 on any column pin is for the keypad button
to be pressed that connects the row set to 0 to a row. The controller knows which column is at a
0-level and which column reads 0, allowing it to determine which key is pressed. For the keypad
scan timing as show in below.
E
D
B
7
FF
FF
FB
FF
ROW_OUT[3:0]
0
1
2
2
1
0
0
1
2
0
1
2
0
1
2
0
1
2
COL_IN[7:0]
ROW_CHANGE
ROW_SCAN_END
PRSCALE x PRESCALDIV
xCLOCK
KPE22
Figure 5.33-4 4x8 Keypad Scan Timing Diagram