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interface keypad 4x4 with PIC16F876A
- Thread starter ayiemaru
- Start date
a 4X4 Keypad scanning uses a full 8 bit port, 4 rows by 4 columns.
So if bits 0-3 are the columns and bits 4-7 are the rows, you make bit 0 high then scan 4-7 to see if a bit has changed state, then make bit 0 low and bit 1high and scan bits 4-7 again, repeat for bits 2&3,
so your programme would make bits 0-3 outputs and bits 4-7 inputs, a total of 16 keys scanned.
So if bits 0-3 are the columns and bits 4-7 are the rows, you make bit 0 high then scan 4-7 to see if a bit has changed state, then make bit 0 low and bit 1high and scan bits 4-7 again, repeat for bits 2&3,
so your programme would make bits 0-3 outputs and bits 4-7 inputs, a total of 16 keys scanned.
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