KEYPAD PORT
The second example uses ON KEYPAD to generate an interrupt every time a key is pressed.
10 ON KEYPAD1000
.
.
.
500 GOTO 500
1000 PRINT KEYPAD(0)
1100 RETURN
Line 10 sets up the tasker for keypad interrupts to start at line 1000. Line 500 loops on itself for demonstration purposes.
Line 1000 prints out the key pad position pressed.
Elem ents of the pr evious pr ogram can be com bined with this one to produce keypad strings.
SECTION 9
KEYPAD PORT PIN OUT - J5
The keypad port uses ports B and C from an 82C55. Lowe r por t C is configu red as an input. Upper port C and port B bits 0 and 1 are ou tputs.
The table b elow lists J5' s pin out, 82C55 p ort and bit, and its intended function.
Pin | 82C55 | Function |
| Port/ bit |
|
1 | C/0 | Row 1 |
2 | C/6 | Column 3 |
3 | C/5 | Column 2 |
4 | C/1 | Row 2 |
5 | C/2 | Row 3 |
6 | C/4 | Column 1 |
7 | C/7 | Column 4 |
8 | C/3 | Row 4 |
9 | B/0 | Column 5 |
10 | B/1 | Column 6 |
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