Hackpad/firmware_arduino/hackpad/hackpad.ino

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2023-04-11 15:59:25 +00:00
//=============================================================================
// iR Hackpad Demo Firmware
// Compile for Arduino Leonardo
//=============================================================================
// The Arduino Keyboard library creates a HID keyboard interface to send keyboard scancodes to the host.
// For convenience, the class takes ASCII characters via Keyboard::write(), which are automatically
// converted to the corresponding keboard scan-codes according to the keyboard layout passed to
// Keyboard::begin(). On the host side, the scan-codes are again converted to characters by the OS.
#include "Keyboard.h"
//=============================================================================
// Our key matrix (see schematics)
const int N_rows = 5;
const int N_cols = 4;
const int gpio_rows[N_rows] = { 6, 7, 8, 9, 5 };
const int gpio_cols[N_cols] = { 15, 14, 16, 10 };
// Key function assignment: ASCII characters or special function codes (see Keyboard.h)
const int key_matrix[N_rows][N_cols] = {
{'a', 'b', 'c', 'd'}, // 4x4 keypad
{'e', 'f', 'g', 'h'},
{'i', 'j', 'k', 'l'},
{'m', 'n', 'o', 'p'},
{'_', '_', '_', 'x'} // rotery encoder button
};
// Key state
struct {
bool last; // Last debounced state
bool inhibit; // State change inhibited during debounce period
uint32_t since_ms; // Inhibited since timestamp
} key_state[N_rows][N_cols];
const uint32_t KEY_DEBOUNCE_MS = 50; // Key Debounce period
const uint32_t KEY_SCAN_DELAY_US = 200; // Delay between row scans
//=============================================================================
void setup()
{
for (int col=0; col<N_cols; col++) {
pinMode(gpio_cols[col], INPUT_PULLUP); // Key matrix columns as inputs
}
for (int row=0; row<N_rows; row++) {
digitalWrite(gpio_rows[row], HIGH);
pinMode(gpio_rows[row], OUTPUT); // Key matrix rows as outputs
}
memset( &key_state, 0, sizeof(key_state) ); // Clear key state
Keyboard.begin(KeyboardLayout_de_DE);
Serial.begin(9600); // Open serial port to host, so the IDE can reset the device for reprogramming
}
//=============================================================================
// Key debouncing:
// React immediately to rising edge (pressed == 1 and last_pressed == 0)
// After that, inhibit further state changes for KEY_DEBOUNCE_MS milliseconds.
void eval_key( int row, int col, bool pressed )
{
// Remove inhibit after debounce period
if (key_state[row][col].inhibit &&
((millis() - key_state[row][col].since_ms) > KEY_DEBOUNCE_MS)) {
key_state[row][col].inhibit = 0;
}
if (pressed == true) { // Key is pressed?
if (key_state[row][col].last == false) { // Rising edge: Key has just been pressed?
key_state[row][col].last = true;
key_state[row][col].inhibit = true;
key_state[row][col].since_ms = millis();
Keyboard.press(key_matrix[row][col]);
}
// TODO: Repeat delay, repeat rate
}
else { // Pressed == false
if (!key_state[row][col].inhibit)
key_state[row][col].last = false;
Keyboard.release(key_matrix[row][col]);
}
}
//=============================================================================
void loop()
{
for (int row=0; row<N_rows; row++) {
digitalWrite(gpio_rows[row], LOW);
for (int col=0; col<N_cols; col++) {
const bool pressed = (digitalRead(gpio_cols[col]) == LOW); // Input level low: Key is pressed
eval_key( row, col, pressed );
}
digitalWrite(gpio_rows[row], HIGH);
delayMicroseconds(KEY_SCAN_DELAY_US); // Give the column inputs time to reach HIGH state (slow recharge via weak pullups)
}
}
//=============================================================================