Gert Jan Schoneveld
Fork without short circuits
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.
Diff: keypad.cpp
- Revision:
- 13:fb6929fac0db
- Parent:
- 12:e6623f165199
- Child:
- 14:f6c3647bf421
--- a/keypad.cpp Sat Nov 03 23:43:46 2012 +0000
+++ b/keypad.cpp Sun Nov 04 09:49:35 2012 +0000
@@ -86,6 +86,35 @@
return r * col_count + c;
}
+int Keypad::DebouncedScanMultiple()
+{
+ /* debounce */
+ int key1 = ScanMultiple();
+
+ wait_ms(_debounce);
+
+ int key2 = ScanMultiple();
+
+ return key1 & key2;
+}
+
+int Keypad::ScanMultiple()
+{
+ int res = 0;
+
+ int i = 0;
+ for (int c = 0; c < col_count; c++) {
+ _cols = ~(1 << c);
+ for (int r = 0; r < row_count; r++) {
+ if (*_rows[r] == 0) {
+ res |= 1 << (r * col_count + c);
+ }
+ i++;
+ }
+ }
+
+ return res;
+}
void Keypad::_callback()
{