qmk_firmware/keyboards/gboards/gergo/gergo.c

// Jane Bernhardt (https://github.com/germ)
// SPDX-License-Identifier: GPL-2.0+

#include "gergo.h"

bool i2c_initialized = 0;
i2c_status_t mcp23018_status = 0x20;

void matrix_init_kb(void) {
    // (tied to Vcc for hardware convenience)
    //gpio_set_pin_input(B4);  // set B(4) as input, internal pull-up disabled

    // unused pins - C7, D4, D5, D6, D7, E6
    // set as input with internal pull-up enabled
    gpio_set_pin_input_high(C7);
    gpio_set_pin_input_high(D4);
    gpio_set_pin_input_high(D5);
    gpio_set_pin_input_high(D6);
    gpio_set_pin_input_high(D7);
    gpio_set_pin_input_high(E6);

    matrix_init_user();
}


uint8_t init_mcp23018(void) {
    print("starting init");
    mcp23018_status = 0x20;

    // I2C subsystem

    // uint8_t sreg_prev;
    // sreg_prev=SREG;
    // cli();

    if (i2c_initialized == 0) {
        i2c_init();  // on pins D(1,0)
        i2c_initialized = true;
        _delay_ms(1000);
    }
    // i2c_init(); // on pins D(1,0)
    // _delay_ms(1000);

    // set pin direction
    // - unused  : input  : 1
    // - input   : input  : 1
    // - driving : output : 0
    uint8_t data[] = {0b10000000, 0b11111111};
    mcp23018_status = i2c_write_register(I2C_ADDR, IODIRA, data, sizeof(data), I2C_TIMEOUT);

    if (!mcp23018_status) {
        // set pull-up
        // - unused  : on  : 1
        // - input   : on  : 1
        // - driving : off : 0
        mcp23018_status = i2c_write_register(I2C_ADDR, GPPUA, data, sizeof(data), I2C_TIMEOUT);
    }

    // SREG=sreg_prev;
    //uprintf("Init %x\n", mcp23018_status);
    return mcp23018_status;
}

const keypos_t PROGMEM hand_swap_config[MATRIX_ROWS][MATRIX_COLS] = {
    { {0,0}, {0,7}, {2,7}, {3,7} },
    { {0,8}, {1,8}, {2,8}, {3,8} },
    { {0,9}, {1,9}, {2,9}, {3,9} },
    { {0,10}, {1,10}, {2,10}, {3,10} },
    { {0,11}, {1,11}, {2,11}, {3,11} },
    { {0,12}, {1,12}, {2,12}, {0,0} },
    { {0,13}, {1,13}, {2,13}, {0,0} },

    { {1,0}, {0,0}, {2,0}, {3,0} },
    { {0,1}, {1,1}, {2,1}, {3,1} },
    { {0,2}, {1,2}, {2,2}, {3,2} },
    { {0,3}, {1,3}, {2,3}, {3,3} },
    { {0,4}, {1,4}, {2,4}, {3,4} },
    { {0,5}, {1,5}, {2,5}, {3,5} },
    { {0,6}, {1,6}, {2,6}, {3,6} }
};