tcs34725.tc

TCS34725 RGB Color Sensor Driver

Source on GitHub

// TCS34725 RGB Color Sensor Driver
// I2C address: 0x29, requires initialization
// Reads RGBC (Red, Green, Blue, Clear) + calculates Lux and Color Temperature
// DN40 algorithm for lux/CT calculation
// Command bit 0x80 must be OR'd with register address
// Auto-increment 0xA0 for block reads

#define TCS_ADDR    0x29
#define TCS_CMD     0x80
#define TCS_AUTOINC 0xA0

// Registers
#define TCS_ENABLE  0x00
#define TCS_ATIME   0x01
#define TCS_CONTROL 0x0F
#define TCS_ID      0x12
#define TCS_STATUS  0x13
#define TCS_CDATAL  0x14

// Integration time 154ms (0xC0) — good range, max ~65535 counts
#define TCS_ATIME_VAL  0xC0
#define TCS_ATIME_MS   154

// Gain 4X
#define TCS_GAIN_VAL   0x01
#define TCS_GAIN_FACT  4

int tcs_addr = 0;
int tcs_bus = 0;
int tcs_ok = 0;
int tcs_r = 0;
int tcs_g = 0;
int tcs_b = 0;
int tcs_c = 0;
float tcs_lux = 0.0;
float tcs_ct = 0.0;

char tcs_buf[8];

int tcs_init() {
    // Verify chip ID (0x44 = TCS34725, 0x10 = TCS34721)
    int id = i2cRead8(tcs_addr, TCS_CMD | TCS_ID, tcs_bus);
    if (id != 0x44 && id != 0x10) {
        return 0;
    }

    // Power ON (PON bit)
    i2cWrite8(tcs_addr, TCS_CMD | TCS_ENABLE, 0x01, tcs_bus);
    delay(3);

    // Set integration time
    i2cWrite8(tcs_addr, TCS_CMD | TCS_ATIME, TCS_ATIME_VAL, tcs_bus);

    // Set gain
    i2cWrite8(tcs_addr, TCS_CMD | TCS_CONTROL, TCS_GAIN_VAL, tcs_bus);

    // Enable RGBC (PON | AEN)
    i2cWrite8(tcs_addr, TCS_CMD | TCS_ENABLE, 0x03, tcs_bus);

    return 1;
}

int tcs_scan() {
    int bus = 0;
    while (bus < 2) {
        if (i2cSetDevice(TCS_ADDR, bus)) {
            tcs_addr = TCS_ADDR;
            tcs_bus = bus;
            if (tcs_init()) {
                i2cSetActiveFound(tcs_addr, "TCS34725", tcs_bus);
                return 1;
            }
            tcs_addr = 0;
        }
        bus++;
    }
    return 0;
}

void EverySecond() {
    if (!tcs_addr) {
        if (!tcs_scan()) { tcs_ok = 0; return; }
    }

    // Check AVALID bit (bit 0) in STATUS register
    int status = i2cRead8(tcs_addr, TCS_CMD | TCS_STATUS, tcs_bus);
    if (!(status & 0x01)) {
        return;  // conversion not ready
    }

    // Block read 8 bytes: C_L, C_H, R_L, R_H, G_L, G_H, B_L, B_H
    if (!i2cReadRS(tcs_addr, TCS_AUTOINC | TCS_CDATAL, tcs_buf, 8, tcs_bus)) {
        tcs_ok = 0;
        return;
    }

    tcs_c = tcs_buf[0] | (tcs_buf[1] << 8);
    tcs_r = tcs_buf[2] | (tcs_buf[3] << 8);
    tcs_g = tcs_buf[4] | (tcs_buf[5] << 8);
    tcs_b = tcs_buf[6] | (tcs_buf[7] << 8);

    // DN40 lux and color temperature calculation
    if (tcs_c > 0 && tcs_r > 0) {
        // IR estimate
        int ir = (tcs_r + tcs_g + tcs_b - tcs_c) / 2;
        if (ir < 0) ir = 0;

        // CPL = (atime_ms * gain) / (GA * DF)
        // GA=1.0, DF=310.0, with 154ms and 4X: CPL = 1.987
        float cpl = (float)(TCS_ATIME_MS * TCS_GAIN_FACT) / 310.0;

        // Lux (DN40 coefficients)
        float r_comp = (float)(tcs_r - ir);
        float g_comp = (float)(tcs_g - ir);
        float b_comp = (float)(tcs_b - ir);

        tcs_lux = (0.136 * r_comp + 1.0 * g_comp - 0.444 * b_comp) / cpl;
        if (tcs_lux < 0.0) tcs_lux = 0.0;

        // Color temperature (Kelvin)
        if (r_comp > 0.0) {
            tcs_ct = 3810.0 * b_comp / r_comp + 1391.0;
        } else {
            tcs_ct = 0.0;
        }
    } else {
        tcs_lux = 0.0;
        tcs_ct = 0.0;
    }

    tcs_ok = 1;
}

void WebCall() {
    char buf[80];
    if (tcs_ok) {
        sprintf(buf, "{s}TCS34725 Red{m}%d{e}", tcs_r);
        webSend(buf);
        sprintf(buf, "{s}TCS34725 Green{m}%d{e}", tcs_g);
        webSend(buf);
        sprintf(buf, "{s}TCS34725 Blue{m}%d{e}", tcs_b);
        webSend(buf);
        sprintf(buf, "{s}TCS34725 Clear{m}%d{e}", tcs_c);
        webSend(buf);
        sprintf(buf, "{s}TCS34725 Lux{m}%.0f lx{e}", tcs_lux);
        webSend(buf);
        sprintf(buf, "{s}TCS34725 CT{m}%.0f K{e}", tcs_ct);
        webSend(buf);
    } else {
        webSend("{s}TCS34725{m}no data{e}");
    }
}

void JsonCall() {
    if (!tcs_ok) return;
    char buf[96];
    sprintf(buf, ",\"TCS34725\":{\"Red\":%d", tcs_r);
    responseAppend(buf);
    sprintf(buf, ",\"Green\":%d", tcs_g);
    responseAppend(buf);
    sprintf(buf, ",\"Blue\":%d", tcs_b);
    responseAppend(buf);
    sprintf(buf, ",\"Clear\":%d", tcs_c);
    responseAppend(buf);
    sprintf(buf, ",\"Lux\":%.0f", tcs_lux);
    responseAppend(buf);
    sprintf(buf, ",\"CT\":%.0f}", tcs_ct);
    responseAppend(buf);
}

void OnExit() {
    if (tcs_addr) {
        // Power off sensor
        i2cWrite8(tcs_addr, TCS_CMD | TCS_ENABLE, 0x00, tcs_bus);
        I2cResetActive(tcs_addr, tcs_bus);
        tcs_addr = 0;
    }
}

int main() {
    char buf[48];
    tcs_ok = 0;
    tcs_addr = 0;

    if (tcs_scan()) {
        sprintf(buf, "TCS34725 found at 0x%x on bus %d", tcs_addr, tcs_bus);
        addLog(buf);
    } else {
        addLog("TCS34725 not found");
    }
    return 0;
}