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Keyboard: read pressed key (untested)

main
radex 2024-02-10 10:32:21 +01:00
parent 6acee37a7f
commit c8f72826d1
Signed by: radex
SSH Key Fingerprint: SHA256:hvqRXAGG1h89yqnS+cyFTLKQbzjWD4uXIqw7Y+0ws30
1 changed files with 69 additions and 5 deletions
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74
firmware/src/keyboard.cpp
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@ -2,9 +2,27 @@
#include <Wire.h>
#include "constants.h"
#include "debug.h"
PCF8574 kbd(KBD_I2C_ADDR, &Wire);
/*
Keyboard layout:
row/col 0 1 2 3
0 1 2 3 A
1 4 5 6 B
2 7 8 9 C
3 * 0 # D
Keys, in order:
123A 456B 789C *0#D
*/
typedef uint8_t Key;
#define KEY_NONE 255
bool setupKeyboard() {
if (!kbd.begin()) {
Serial.println("Could not initialize keyboard");
@ -18,10 +36,56 @@ bool setupKeyboard() {
return true;
}
Key getPressedKey();
#define KBD_COL_MASK 0b11110000
#define KBD_ROW_MASK 0b00001111
void demoKeyboard() {
kbd.write8(0b11110000); // first 4 bits are columns, low when pressed
// kbd.write8(0b00001111); // last 4 bits are rows, low when pressed
int x = kbd.read8();
Serial.print("Keyboard: ");
Serial.println(x, BIN);
String allKeys = F("123A456B789C*0#D");
auto key = getPressedKey();
if (key != KEY_NONE) {
Serial.print("Key pressed: ");
Serial.println(allKeys[key]);
}
}
/**
* Returns pressed key or KEY_NONE if no key is pressed
*
* NOTE: Only one key can be pressed at a time;
* if multiple keys are pressed, the result is undefined
*/
Key getPressedKey() {
// check pressed column
// first 4 bits are columns, low when pressed
kbd.write8(KBD_COL_MASK);
uint8_t cols = kbd.read8();
if (cols == KBD_COL_MASK) {
return KEY_NONE;
}
uint8_t colState = ~(cols >> 4);
uint8_t colPressed = 0;
if (colState & 0b1000) colPressed = 0;
else if (colState & 0b0100) colPressed = 1;
else if (colState & 0b0010) colPressed = 2;
else if (colState & 0b0001) colPressed = 3;
else fatal();
// check pressed row
// last 4 bits are rows, low when pressed
kbd.write8(KBD_ROW_MASK);
uint8_t rowState = ~kbd.read8();
uint8_t rowPressed = 0;
if (rowState & 0b1000) rowPressed = 0;
else if (rowState & 0b0100) rowPressed = 1;
else if (rowState & 0b0010) rowPressed = 2;
else if (rowState & 0b0001) rowPressed = 3;
else fatal();
// return key
return (rowPressed * 4) + colPressed;
}