qmk-dactyl-manuform-a/keyboards/handwired/onekey/keymaps/i2c_scanner/keymap.c

#include QMK_KEYBOARD_H

#include "i2c_master.h"
#include "debug.h"

#define TIMEOUT 50

// TODO: remove patch
#ifdef PROTOCOL_CHIBIOS
#    pragma message("ChibiOS is currently 'best effort' and might not report accurate results")

i2c_status_t i2c_start_bodge(uint8_t address, uint16_t timeout) {
    i2c_start(address);

    // except on ChibiOS where the only way is do do "something"
    uint8_t data = 0;
    return i2c_readReg(address, 0, &data, sizeof(data), TIMEOUT);
}

#    define i2c_start i2c_start_bodge
#endif

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    LAYOUT_ortho_1x1(KC_A)
};

void do_scan(void) {
    uint8_t nDevices = 0;

    dprintf("Scanning...\n");

    for (uint8_t address = 1; address < 127; address++) {
        // The i2c_scanner uses the return value of
        // i2c_start to see if a device did acknowledge to the address.
        i2c_status_t error = i2c_start(address << 1, TIMEOUT);
        if (error == I2C_STATUS_SUCCESS) {
            i2c_stop();
            dprintf("  I2C device found at address 0x%02X\n", address);
            nDevices++;
        } else {
            // dprintf("  Unknown error (%u) at address 0x%02X\n", error, address);
        }
    }

    if (nDevices == 0)
        dprintf("No I2C devices found\n");
    else
        dprintf("done\n");
}

uint16_t scan_timer = 0;

void matrix_scan_user(void) {
    if (timer_elapsed(scan_timer) > 5000) {
        do_scan();
        scan_timer = timer_read();
    }
}

void keyboard_post_init_user(void) {
    debug_enable = true;
    debug_matrix = true;

    i2c_init();
    scan_timer = timer_read();
}