Gert Jan Schoneveld / keypad

Fork without short circuits

Dependents:   SaveKeypad

Fork of keypad by HM Yoong

No extra hardware is needed besides the wires and switches. The columns are outputs configured with open drain. The rows are inputs configured with pull up resistors. A key press pulls down its row. With scanning the column is determined thereafter.

See SaveKeypad for an example usage.

keypad.cpp@16:a9feaa7ac039, 2012-11-08 (annotated)

Committer:
gj_schoneveld
Date:
Thu Nov 08 19:04:08 2012 +0000
Revision:
16:a9feaa7ac039
Parent:
15:873a9a452ef1 
Updated Debounce

Who changed what in which revision?

UserRevisionLine numberNew contents of line
yoonghm 0:2df66331c109 1 #include "keypad.h"
yoonghm 0:2df66331c109 2
yoonghm 0:2df66331c109 3 Keypad::Keypad(PinName row3, PinName row2, PinName row1, PinName row0,
yoonghm 0:2df66331c109 4 PinName col3, PinName col2, PinName col1, PinName col0,
yoonghm 0:2df66331c109 5 int debounce_ms):
gj_schoneveld 10:9a9ec143840b 6 _row0(row0), _row1(row1), _row2(row2), _row3(row3),
gj_schoneveld 10:9a9ec143840b 7 _cols(col0, col1, col2, col3)
gj_schoneveld 10:9a9ec143840b 8 {
gj_schoneveld 12:e6623f165199 9 _debounce = debounce_ms;
gj_schoneveld 11:a45e64141ce6 10 _rows[0] = &_row0;
gj_schoneveld 11:a45e64141ce6 11 _rows[1] = &_row1;
gj_schoneveld 11:a45e64141ce6 12 _rows[2] = &_row2;
gj_schoneveld 11:a45e64141ce6 13 _rows[3] = &_row3;
gj_schoneveld 12:e6623f165199 14 for (int r = 0; r < row_count; r++)
gj_schoneveld 12:e6623f165199 15 _rows[r]->mode(PullUp);
gj_schoneveld 10:9a9ec143840b 16 _cols.mode(OpenDrain);
gj_schoneveld 10:9a9ec143840b 17 _cols.output();
gj_schoneveld 11:a45e64141ce6 18 }
gj_schoneveld 11:a45e64141ce6 19
gj_schoneveld 11:a45e64141ce6 20 void Keypad::_setupFallTrigger(void)
gj_schoneveld 11:a45e64141ce6 21 {
gj_schoneveld 12:e6623f165199 22 for (int r = 0; r < row_count; r++)
gj_schoneveld 12:e6623f165199 23 _rows[r]->fall(this, &Keypad::_callback);
yoonghm 0:2df66331c109 24 }
yoonghm 0:2df66331c109 25
gj_schoneveld 10:9a9ec143840b 26 void Keypad::Start(void)
gj_schoneveld 10:9a9ec143840b 27 {
gj_schoneveld 11:a45e64141ce6 28 /* make the columns zero so they can pull rows down */
yoonghm 0:2df66331c109 29 _cols = 0x00;
yoonghm 0:2df66331c109 30 }
yoonghm 0:2df66331c109 31
gj_schoneveld 10:9a9ec143840b 32 void Keypad::Stop(void)
gj_schoneveld 10:9a9ec143840b 33 {
gj_schoneveld 11:a45e64141ce6 34 /* make the columns one so they cannot pull any rows down anymore */
gj_schoneveld 11:a45e64141ce6 35 _cols = ~0x00;
gj_schoneveld 10:9a9ec143840b 36 }
gj_schoneveld 10:9a9ec143840b 37
gj_schoneveld 10:9a9ec143840b 38 void Keypad::CallAfterInput(uint32_t (*fptr)(uint32_t index))
gj_schoneveld 10:9a9ec143840b 39 {
yoonghm 0:2df66331c109 40 _input.attach(fptr);
gj_schoneveld 11:a45e64141ce6 41 _setupFallTrigger();
gj_schoneveld 11:a45e64141ce6 42 }
gj_schoneveld 11:a45e64141ce6 43
gj_schoneveld 11:a45e64141ce6 44 int Keypad::DebouncedScan()
gj_schoneveld 11:a45e64141ce6 45 {
gj_schoneveld 12:e6623f165199 46 /* debounce */
gj_schoneveld 11:a45e64141ce6 47 wait_ms(_debounce);
gj_schoneveld 16:a9feaa7ac039 48
gj_schoneveld 16:a9feaa7ac039 49 return Scan();
yoonghm 0:2df66331c109 50 }
yoonghm 0:2df66331c109 51
gj_schoneveld 11:a45e64141ce6 52 int Keypad::Scan()
gj_schoneveld 10:9a9ec143840b 53 {
gj_schoneveld 11:a45e64141ce6 54 /* lookup row */
gj_schoneveld 11:a45e64141ce6 55 int r = -1;
gj_schoneveld 11:a45e64141ce6 56 for (r = 0; r < row_count; r++) {
gj_schoneveld 11:a45e64141ce6 57 if (*_rows[r] == 0)
gj_schoneveld 11:a45e64141ce6 58 break;
gj_schoneveld 11:a45e64141ce6 59 }
yoonghm 0:2df66331c109 60
gj_schoneveld 11:a45e64141ce6 61 /* if we didn't find a valid row, return */
gj_schoneveld 11:a45e64141ce6 62 if (!(0 <= r && r < row_count))
gj_schoneveld 11:a45e64141ce6 63 return -1;
gj_schoneveld 11:a45e64141ce6 64
gj_schoneveld 16:a9feaa7ac039 65 /* scan columns to find out which one pulls down the row */
yoonghm 0:2df66331c109 66 int c = -1;
gj_schoneveld 11:a45e64141ce6 67 for (c = 0; c < col_count; c++) {
gj_schoneveld 11:a45e64141ce6 68 _cols = ~(1 << c);
gj_schoneveld 11:a45e64141ce6 69 if (*_rows[r] == 0)
gj_schoneveld 11:a45e64141ce6 70 break;
yoonghm 0:2df66331c109 71 }
gj_schoneveld 11:a45e64141ce6 72
gj_schoneveld 11:a45e64141ce6 73 /* re-energize all columns */
gj_schoneveld 11:a45e64141ce6 74 Start();
gj_schoneveld 11:a45e64141ce6 75
gj_schoneveld 11:a45e64141ce6 76 /* if we didn't find a valid column, return */
gj_schoneveld 11:a45e64141ce6 77 if (!(0 <= c && c < col_count))
gj_schoneveld 11:a45e64141ce6 78 return -1;
gj_schoneveld 11:a45e64141ce6 79
gj_schoneveld 11:a45e64141ce6 80 return r * col_count + c;
yoonghm 0:2df66331c109 81 }
gj_schoneveld 16:a9feaa7ac039 82
gj_schoneveld 13:fb6929fac0db 83 int Keypad::DebouncedScanMultiple()
gj_schoneveld 13:fb6929fac0db 84 {
gj_schoneveld 13:fb6929fac0db 85 /* debounce */
gj_schoneveld 13:fb6929fac0db 86 wait_ms(_debounce);
gj_schoneveld 16:a9feaa7ac039 87
gj_schoneveld 16:a9feaa7ac039 88 return ScanMultiple();
gj_schoneveld 13:fb6929fac0db 89 }
gj_schoneveld 13:fb6929fac0db 90
gj_schoneveld 13:fb6929fac0db 91 int Keypad::ScanMultiple()
gj_schoneveld 13:fb6929fac0db 92 {
gj_schoneveld 16:a9feaa7ac039 93 int res = 0;
gj_schoneveld 13:fb6929fac0db 94 for (int c = 0; c < col_count; c++) {
gj_schoneveld 13:fb6929fac0db 95 _cols = ~(1 << c);
gj_schoneveld 13:fb6929fac0db 96 for (int r = 0; r < row_count; r++) {
gj_schoneveld 13:fb6929fac0db 97 if (*_rows[r] == 0) {
gj_schoneveld 13:fb6929fac0db 98 res |= 1 << (r * col_count + c);
gj_schoneveld 13:fb6929fac0db 99 }
gj_schoneveld 13:fb6929fac0db 100 }
gj_schoneveld 13:fb6929fac0db 101 }
gj_schoneveld 16:a9feaa7ac039 102
gj_schoneveld 13:fb6929fac0db 103 return res;
gj_schoneveld 13:fb6929fac0db 104 }
yoonghm 0:2df66331c109 105
gj_schoneveld 11:a45e64141ce6 106 void Keypad::_callback()
gj_schoneveld 10:9a9ec143840b 107 {
gj_schoneveld 11:a45e64141ce6 108 /* lookup */
gj_schoneveld 11:a45e64141ce6 109 int position = DebouncedScan();
gj_schoneveld 16:a9feaa7ac039 110
gj_schoneveld 11:a45e64141ce6 111 /* call back a valid position */
gj_schoneveld 11:a45e64141ce6 112 if (position >= 0)
gj_schoneveld 11:a45e64141ce6 113 _input.call(position);
yoonghm 0:2df66331c109 114 }
gj_schoneveld 14:f6c3647bf421 115