veml6075.tc

VEML6075 UV Light Sensor Driver

Source on GitHub

// VEML6075 UV Light Sensor Driver
// I2C address: 0x10, 16-bit registers (LSB first)
// Reads UVA, UVB with compensation and calculates UV Index
// Compensation removes visible light and IR interference
// DN40 responsivity for UV Index calculation

#define VEML_ADDR    0x10
#define VEML_CONF    0x00
#define VEML_UVA     0x07
#define VEML_UVB     0x09
#define VEML_UVCOMP1 0x0A
#define VEML_UVCOMP2 0x0B
#define VEML_ID      0x0C

int veml_addr = 0;
int veml_bus = 0;
int veml_ok = 0;
int veml_uva = 0;
int veml_uvb = 0;
float veml_uvi = 0.0;

char veml_buf[2];

// Read 16-bit register (LSB first)
int veml_read16(int reg) {
    if (!i2cReadRS(veml_addr, reg, veml_buf, 2, veml_bus)) {
        return -1;
    }
    return veml_buf[0] | (veml_buf[1] << 8);
}

// Write 16-bit register (LSB first)
int veml_write16(int reg, int val) {
    veml_buf[0] = val & 0xFF;
    veml_buf[1] = (val >> 8) & 0xFF;
    return i2cWrite(veml_addr, reg, veml_buf, 2, veml_bus);
}

int veml_init() {
    // Verify chip ID (expect 0x0026)
    int id = veml_read16(VEML_ID);
    if (id != 0x26) {
        return 0;
    }
    // Config: 100ms integration (inttime=1 in bits 6:4), active mode
    veml_write16(VEML_CONF, 0x10);
    return 1;
}

int veml_scan() {
    int bus = 0;
    while (bus < 2) {
        if (i2cSetDevice(VEML_ADDR, bus)) {
            veml_addr = VEML_ADDR;
            veml_bus = bus;
            if (veml_init()) {
                i2cSetActiveFound(veml_addr, "VEML6075", veml_bus);
                return 1;
            }
            veml_addr = 0;
        }
        bus++;
    }
    return 0;
}

void EverySecond() {
    if (!veml_addr) {
        if (!veml_scan()) { veml_ok = 0; return; }
    }

    int uva_raw = veml_read16(VEML_UVA);
    int uvb_raw = veml_read16(VEML_UVB);
    int comp1   = veml_read16(VEML_UVCOMP1);
    int comp2   = veml_read16(VEML_UVCOMP2);

    if (uva_raw < 0 || uvb_raw < 0 || comp1 < 0 || comp2 < 0) {
        veml_ok = 0;
        return;
    }

    // Compensate for visible light and IR interference
    float uva_comp = (float)uva_raw - 2.22 * (float)comp1 - 1.33 * (float)comp2;
    float uvb_comp = (float)uvb_raw - 2.95 * (float)comp1 - 1.74 * (float)comp2;
    if (uva_comp < 0.0) uva_comp = 0.0;
    if (uvb_comp < 0.0) uvb_comp = 0.0;

    veml_uva = (int)uva_comp;
    veml_uvb = (int)uvb_comp;

    // UV Index (100ms responsivity: UVA=0.001461, UVB=0.002591)
    veml_uvi = (uva_comp * 0.001461 + uvb_comp * 0.002591) / 2.0;

    veml_ok = 1;
}

void WebCall() {
    char buf[64];
    if (veml_ok) {
        sprintf(buf, "{s}VEML6075 UVA{m}%d{e}", veml_uva);
        webSend(buf);
        sprintf(buf, "{s}VEML6075 UVB{m}%d{e}", veml_uvb);
        webSend(buf);
        sprintf(buf, "{s}VEML6075 UV Index{m}%.1f{e}", veml_uvi);
        webSend(buf);
    } else {
        webSend("{s}VEML6075{m}no data{e}");
    }
}

void JsonCall() {
    if (!veml_ok) return;
    char buf[96];
    sprintf(buf, ",\"VEML6075\":{\"UVA\":%d", veml_uva);
    responseAppend(buf);
    sprintf(buf, ",\"UVB\":%d", veml_uvb);
    responseAppend(buf);
    sprintf(buf, ",\"UVI\":%.1f}", veml_uvi);
    responseAppend(buf);
}

void OnExit() {
    if (veml_addr) {
        // Shutdown sensor (set pwr bit)
        veml_write16(VEML_CONF, 0x01);
        I2cResetActive(veml_addr, veml_bus);
        veml_addr = 0;
    }
}

int main() {
    char buf[48];
    veml_ok = 0;
    veml_addr = 0;

    if (veml_scan()) {
        sprintf(buf, "VEML6075 found at 0x%x on bus %d", veml_addr, veml_bus);
        addLog(buf);
    } else {
        addLog("VEML6075 not found");
    }
    return 0;
}