ads1115.tc

// ADS1115 16-bit 4-Channel ADC Driver
// I2C addresses: 0x48 (ADDR=GND), 0x49 (ADDR=VDD), 0x4A (ADDR=SDA), 0x4B (ADDR=SCL)
// Single-ended mode: reads AIN0..AIN3 vs GND
// Configurable PGA gain, single-shot conversion
// Displays voltage on web UI + JSON teleperiod + 6h chart

#define ADS_ADDR1  0x48
#define ADS_ADDR2  0x4B

// PGA gain settings (config bits 11-9)
// Change ADS_PGA to match your voltage range
#define PGA_6144   0   // ±6.144V  (LSB = 187.5µV)
#define PGA_4096   1   // ±4.096V  (LSB = 125µV)
#define PGA_2048   2   // ±2.048V  (LSB = 62.5µV)  — default
#define PGA_1024   3   // ±1.024V  (LSB = 31.25µV)
#define PGA_0512   4   // ±0.512V  (LSB = 15.625µV)
#define PGA_0256   5   // ±0.256V  (LSB = 7.8125µV)

// *** Configuration — adjust to your needs ***
#define ADS_PGA       PGA_4096    // gain setting
#define ADS_CHANNELS  4           // number of channels to read (1..4)

// LSB voltage in µV for each PGA setting (index = PGA value)
// We store as int µV to avoid float array init issues
// PGA_6144=187500, PGA_4096=125000, PGA_2048=62500, PGA_1024=31250, PGA_0512=15625, PGA_0256=7813

int ads_addr = 0;
int ads_bus = 0;
int ads_ok = 0;

// Raw ADC values and voltages per channel
int ads_raw[4];
float ads_volt[4];

// I2C buffer for 2-byte reads/writes
char ads_buf[4];

// Chart history (6h at 1/min = 360)
#define CHART_LEN 360
float hist_ch0[CHART_LEN];
float hist_ch1[CHART_LEN];
float hist_ch2[CHART_LEN];
float hist_ch3[CHART_LEN];
int hist_pos;
int hist_tick;

// Get LSB size in µV for current PGA setting
float ads_get_lsb() {
    if (ADS_PGA == 0) return 187.5;
    if (ADS_PGA == 1) return 125.0;
    if (ADS_PGA == 2) return 62.5;
    if (ADS_PGA == 3) return 31.25;
    if (ADS_PGA == 4) return 15.625;
    return 7.8125;
}

// Sign-extend 16-bit to signed int
int sign16(int val) {
    if (val >= 32768) return val - 65536;
    return val;
}

// Scan for ADS1115 on both buses
int ads_scan() {
    int bus = 0;
    while (bus < 2) {
        int addr = ADS_ADDR1;
        while (addr <= ADS_ADDR2) {
            if (i2cSetDevice(addr, bus)) {
                // Read config register — default after reset is 0x8583
                if (i2cRead(addr, 0x01, ads_buf, 2, bus)) {
                    int cfg = (ads_buf[0] << 8) | ads_buf[1];
                    // Check bits that should be default: DR=100 (128SPS), MODE=1
                    // Default config = 0x8583, but just check device responds
                    if (cfg != 0 && cfg != 0xFFFF) {
                        ads_addr = addr;
                        ads_bus = bus;
                        i2cSetActiveFound(ads_addr, "ADS1115", ads_bus);
                        return 1;
                    }
                }
            }
            addr++;
        }
        bus++;
    }
    return 0;
}

// Read one channel (0-3) in single-shot mode, returns raw signed value
int ads_read_channel(int ch) {
    // Config register: OS=1 (start), MUX=1xx (single-ended AINx), PGA, MODE=1 (single-shot)
    // DR=100 (128SPS), COMP_QUE=11 (disable comparator)
    // Byte 0 (high): OS[15] MUX[14:12] PGA[11:9] MODE[8]
    //   OS=1, MUX = 100 + ch, PGA = ADS_PGA, MODE = 1
    // Byte 1 (low): DR[7:5] COMP_MODE[4] COMP_POL[3] COMP_LAT[2] COMP_QUE[1:0]
    //   DR=100 (128SPS), rest=0, COMP_QUE=11
    //   = 10000011 = 0x83

    int mux = 4 + ch;    // 100=AIN0, 101=AIN1, 110=AIN2, 111=AIN3
    int hi = 0x80 | (mux << 4) | (ADS_PGA << 1) | 0x01;
    int lo = 0x83;        // 128 SPS, comparator disabled

    // Write config register
    ads_buf[0] = hi;
    ads_buf[1] = lo;
    if (!i2cWrite(ads_addr, 0x01, ads_buf, 2, ads_bus)) return 0;

    // Wait for conversion (128 SPS = ~8ms, use 10ms margin)
    delay(10);

    // Read conversion register (2 bytes, MSB first)
    if (!i2cRead(ads_addr, 0x00, ads_buf, 2, ads_bus)) return 0;

    int raw = (ads_buf[0] << 8) | ads_buf[1];
    return sign16(raw);
}

void EverySecond() {
    if (!ads_addr) {
        if (!ads_scan()) { ads_ok = 0; return; }
    }

    float lsb = ads_get_lsb();
    int ch = 0;
    while (ch < ADS_CHANNELS) {
        ads_raw[ch] = ads_read_channel(ch);
        // Convert to volts: raw * lsb_µV / 1000000
        ads_volt[ch] = (float)ads_raw[ch] * lsb / 1000000.0;
        ch++;
    }
    ads_ok = 1;

    // Chart history every minute
    hist_tick++;
    if (hist_tick >= 60) {
        hist_tick = 0;
        int p = hist_pos % CHART_LEN;
        hist_ch0[p] = ads_volt[0];
        if (ADS_CHANNELS > 1) hist_ch1[p] = ads_volt[1];
        if (ADS_CHANNELS > 2) hist_ch2[p] = ads_volt[2];
        if (ADS_CHANNELS > 3) hist_ch3[p] = ads_volt[3];
        hist_pos++;
    }
}

void WebPage() {
    int n = hist_pos;
    if (n > CHART_LEN) n = CHART_LEN;
    if (n > 0) {
        // ottelo's chart-centering compensation (margin-left:-30px wrapper)
        webSend("<div style='margin-left:-30px'>");
        WebChart('l', "ADS1115 Voltages", "AIN0 (V)", 0xe74c3c, hist_pos, CHART_LEN, hist_ch0, 1, 0, 0, 0);
        if (ADS_CHANNELS > 1) {
            WebChart('l', "", "AIN1 (V)", 0x3498db, hist_pos, CHART_LEN, hist_ch1, 1, 0, 0, 0);
        }
        if (ADS_CHANNELS > 2) {
            WebChart('l', "", "AIN2 (V)", 0x27ae60, hist_pos, CHART_LEN, hist_ch2, 1, 0, 0, 0);
        }
        if (ADS_CHANNELS > 3) {
            WebChart('l', "", "AIN3 (V)", 0x9b59b6, hist_pos, CHART_LEN, hist_ch3, 1, 0, 0, 0);
        }
        webSend("</div>");
    }
}

void WebCall() {
    char buf[80];
    if (ads_ok) {
        int ch = 0;
        while (ch < ADS_CHANNELS) {
            sprintf(buf, "{s}ADS1115 AIN%d{m}", ch);
            webSend(buf);
            sprintf(buf, "%.4f V{e}", ads_volt[ch]);
            webSend(buf);
            ch++;
        }
    } else {
        webSend("{s}ADS1115{m}not found{e}");
    }
}

void JsonCall() {
    if (!ads_ok) return;
    char buf[64];
    responseAppend(",\"ADS1115\":{");
    int ch = 0;
    while (ch < ADS_CHANNELS) {
        if (ch > 0) responseAppend(",");
        sprintf(buf, "\"A%d\":", ch);
        responseAppend(buf);
        sprintf(buf, "%.4f", ads_volt[ch]);
        responseAppend(buf);
        ch++;
    }
    responseAppend("}");
}

void OnExit() {
    if (ads_addr) {
        I2cResetActive(ads_addr, ads_bus);
        ads_addr = 0;
    }
}

int main() {
    char buf[64];
    ads_ok = 0;
    ads_addr = 0;
    hist_pos = 0;
    hist_tick = 0;

    if (ads_scan()) {
        sprintf(buf, "ADS1115 found at 0x%x on bus %d", ads_addr, ads_bus);
        addLog(buf);
        sprintf(buf, "PGA gain: %d, channels: %d", ADS_PGA, ADS_CHANNELS);
        addLog(buf);
    } else {
        addLog("ADS1115 not found on any bus");
    }
    return 0;
}