gistfile1.md

Setting up a basic encoder with the Teensy 2.0 and TMK

Schematic (using C6 and C7):

All modifications are made to matrix.c.

Code to add near top of file:

uint8_t state;
int32_t position;

static void init_encoder(void)
{
    DDRC &= ~(1<<6 | 1<<7);  // C6 and C7 are the two ports being used
    PORTC |=  (1<<6 | 1<<7); // This sets the ports up for input

    uint8_t s = 0;
    _delay_ms(1);
    if (PINC&(1<<6)) s |= 1; // PINC&(1<<6) reads the value of the C6 port (0 or 1)
    if (PINC&(1<<7)) s |= 2;
    state = s;
    position = 0;
}

void read_encoder(void)
{
    uint8_t s = state & 3;
    if (PINC&(1<<6)) s |= 4;
    if (PINC&(1<<7)) s |= 8;
    state = (s >> 2);
    switch (s) {
        case 1: case 7: case 8: case 14:
            position++; 
            break;
        case 2: case 4: case 11: case 13:
            position--; 
            break;
        case 3: case 12:
            position += 2; 
            break;
        case 6: case 9:
            position -= 2; 
            break;
    }
}

Add init_encoder(); to your matrix_init(void) method.

Code to add to your matrix_scan method:

read_encoder();
if (position >= 2) { // 2 may need to be changed depending on your encoder
    register_code(KC_AUDIO_VOL_UP); // Any keycode should work here
    unregister_code(KC_AUDIO_VOL_UP);
    position = 0;
} else if (position <= -2) { // Change this value as well
    register_code(KC_AUDIO_VOL_DOWN);
    unregister_code(KC_AUDIO_VOL_DOWN);
    position = 0;
}