BME280.cpp

/* support up to two Adafruit BME280 humidity, temperature & pressure sensors connected in I2C mode.
 */

#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

#include "HamClock.h"


// only possible addresses -- correspond to BME_76 and BME_77 indices
#define I2CADDR_1       0x76                    // always at [0] in data arrays below
#define I2CADDR_2       0x77                    // always at [1] in data arrays below

// polling management. polls at START_DT at first then slows to FINAL_DT after steady-state period
#define MAX_BME_AGE     (24*3600L)             // max age to plot, seconds
#define START_DT        (2*1000L)              // initial polling period, millis
#define FINAL_DT        (1000L*MAX_BME_AGE/N_BME_READINGS)      // final polling period, millis
#define SS_START        (1800*1000L)           // when to reach final steady state, millis

// data management.
static const uint8_t bme_i2c[MAX_N_BME] = {I2CADDR_1, I2CADDR_2};    // N.B. match BME_76 and BME_77 indices
static BMEData *bme_data[MAX_N_BME];            // malloced queues, if found
static Adafruit_BME280 bme_io[MAX_N_BME];       // one for each potential sensor

// time management.
static uint32_t readDT = START_DT;              // period between readings, millis();
static uint32_t last_reading;                   // last time either sensor was read, millis()
static bool new_data;                           // whether new data has been read but not displayed

// appearance
#define TEMP_COLOR      RGB565(250,127,120);
#define PRES_COLOR      RA8875_YELLOW
#define HUM_COLOR       RA8875_CYAN
#define DP_COLOR        RA8875_GREEN

/* try to connect to "all" sensors else try to reconnect to ones that originally worked.
 */
static void connectSensors(bool all)
{
    // try to (re)open each sensor
    for (int i = 0; i < MAX_N_BME; i++) {

        // skip unless all or succeeded before
        if (!all && !bme_data[i])
            continue;

        uint8_t addr = bme_i2c[i];
        Serial.printf ("BME %strying 0x%x\n", !bme_data[i] ? "" : "re", addr);
        Adafruit_BME280 &bme = bme_io[i];
        if (!bme.begin(addr)) {
            Serial.printf ("BME init 0x%02X fail\n", addr);
            continue;
        }

        // open worked: init if first time
        if (!bme_data[i]) {
            bme_data[i] = (BMEData *) calloc (1, sizeof(BMEData));
            bme_data[i]->i2c = addr;
        }

        // Forced mode sleeps until read; normal mode runs continuously and warms the sensor
        bme.setSampling(Adafruit_BME280::MODE_FORCED,
                    Adafruit_BME280::SAMPLING_X1, // temperature
                    Adafruit_BME280::SAMPLING_X1, // pressure
                    Adafruit_BME280::SAMPLING_X1, // humidity
                    Adafruit_BME280::FILTER_OFF,
                    Adafruit_BME280::STANDBY_MS_1000);

        // initial readings are a little flaky, read and discard temp until fairly stable
        #define _N_OK 10
        #define _N_TRY (5*_N_OK)
        #define _TOT_DT 5000    // max millis for entire test
        int n_stable = 0;
        float prev_t = 1e6;
        for (int i = 0; i < _N_TRY && n_stable < _N_OK; i++) {
            float t = bme.readTemperature();
            if (!isnan(t) && t > -40) {
                if (fabsf(t-prev_t) < 1)
                    n_stable++;
                else
                    n_stable = 0;
                prev_t = t;
            }
            wdDelay(_TOT_DT/_N_TRY);
        }

        if (n_stable == _N_OK)
            Serial.printf ("BME init 0x%02X success\n", addr);
        else
            Serial.printf ("BME 0x%02X not stable\n", addr);
    }

    if (getNBMEConnected() == 0)
        Serial.println("BME none found");
}

/* read the given temperature, pressure and humidity in user units into next q entry.
 * if ok advance q and return if ok.
 */
static bool readSensor (int device)
{
    // get data pointer, skip if not used
    BMEData *dp = bme_data[device];
    if (!dp)
        return (false);
    Adafruit_BME280 &bme = bme_io[device];

    // note attempt time whether or not we succeed
    last_reading = millis();

    // success?
    bool ok = false;

    // go
    bme.takeForcedMeasurement();
    float t = bme.readTemperature();                                                    // C
    float p = bme.readPressure();                                                       // Pascals
    float h = bme.readHumidity();                                                       // percent
    // Serial.printf ("BME Raw T %g P %g H %g\n", t, p, h);                             // RBF
    if (isnan(t) || t < -40 || isnan(p) || isnan(h)) {
        // try restarting
        Serial.printf ("BME %x read err\n", dp->i2c);
        connectSensors(false);
    } else {
        // all good
        if (showATMhPa())
            dp->p[dp->q_head] = p/100 + getBMEPresCorr(device);                         // Pascals to hPa
        else
            dp->p[dp->q_head] = p / 3386.39 + getBMEPresCorr(device);                   // Pascals to in_Hg
        if (showTempC())
            dp->t[dp->q_head] = t + getBMETempCorr(device);                             // already C
        else
            dp->t[dp->q_head] = 1.8*t + 32.0 + getBMETempCorr(device);                  // C to F
        dp->h[dp->q_head] = h;
        dp->u[dp->q_head] = myNow();

        // Serial.printf ("BME %u %x %7.2f %7.2f %7.2f\n", dp->u[dp->q_head], dp->i2c,
                            // dp->t[dp->q_head], dp->p[dp->q_head], dp->h[dp->q_head]); 

        // advance q
        dp->q_head = (dp->q_head+1)%N_BME_READINGS;
        ok = true;

        // note fresh data is available
        new_data = true;
    }

    // return whether success
    return (ok);
}

/* read all sensors, return whether either was successful
 */
static bool readSensors(void)
{
    bool ok = false;

    for (int device = 0; device < MAX_N_BME; device++)
        if (readSensor (device))
            ok = true;

    return (ok);
}


/* convert temperature and relative humidity to dewpoint.
 * N.B. both temp units are in user units.
 * http://irtfweb.ifa.hawaii.edu/~tcs3/tcs3/Misc/Dewpoint_Calculation_Humidity_Sensor_E.pdf
 */
float dewPoint (float T, float RH)
{
    // beware
    if (RH <= 0)
        return (0);

    // want C
    if (!showTempC())
        T = FAH2CEN(T);
    float H = (log10f(RH)-2)/0.4343F + (17.62F*T)/(243.12F+T);
    float Dp = 243.12F*H/(17.62F-H);
    if (!showTempC())
        Dp = CEN2FAH(Dp);
    return (Dp);
}

/* plot the given sensor data type choice in the given box, if said choice is one of ours
 */
void drawOneBME280Pane (const SBox &box, PlotChoice ch)
{
    for (int i = 0; i < MAX_N_BME; i++) {

        // get data pointer, skip if not used
        BMEData *dp = bme_data[i];
        if (!dp)
            continue;

        // prepare the appropriate plot
        float *valu_q;
        char title[32];
        uint16_t color;
        switch (ch) {
        case PLOT_CH_TEMPERATURE:
            valu_q = dp->t;
            if (showTempC())
                snprintf (title, sizeof(title), "I2C %x: Temperature, C", bme_i2c[i]);
            else
                snprintf (title, sizeof(title), "I2C %x: Temperature, F", bme_i2c[i]);
            color = TEMP_COLOR;
            break;
        case PLOT_CH_PRESSURE:
            valu_q = dp->p;
            if (showATMhPa())
                snprintf (title, sizeof(title), "I2C %x: Pressure, hPa", bme_i2c[i]);
            else
                snprintf (title, sizeof(title), "I2C %x: Pressure, inHg", bme_i2c[i]);
            color = PRES_COLOR;
            break;
        case PLOT_CH_HUMIDITY:
            valu_q = dp->h;
            snprintf (title, sizeof(title), "I2C %x: Humidity, %%", bme_i2c[i]);
            color = HUM_COLOR;
            break;
        case PLOT_CH_DEWPOINT:
            valu_q = NULL;               // DP is derived, see below
            if (showTempC())
                snprintf (title, sizeof(title), "I2C %x: Dew point, C", bme_i2c[i]);
            else
                snprintf (title, sizeof(title), "I2C %x: Dew point, F", bme_i2c[i]);
            color = DP_COLOR;
            break;
        default: 
            // not showing a sensor in this box
            return;
        }

        // build linear x and y
        StackMalloc x_mem(N_BME_READINGS*sizeof(float));
        StackMalloc y_mem(N_BME_READINGS*sizeof(float));
        float *x = (float *) x_mem.getMem();
        float *y = (float *) y_mem.getMem();
        time_t t0 = myNow();
        uint8_t nxy = 0;                                        // count entries with valid times
        float value_now = 0;                                    // latest value is last
        for (int j = 0; j < N_BME_READINGS; j++) {
            uint8_t qj = (dp->q_head + j) % N_BME_READINGS;     // oldest .. newest == qhead .. qhead-1
            if (dp->u[qj] > 0) {                                // skip if time not set
                int age_s = t0 - dp->u[qj];                     // n seconds old
                if (age_s > MAX_BME_AGE)
                    continue;                                   // limit plot age
                x[nxy] = age_s;                                 // rescaled after we know total period
                if (ch == PLOT_CH_DEWPOINT) {
                    value_now = y[nxy] = dewPoint (dp->t[qj], dp->h[qj]);
                } else if (ch == PLOT_CH_TEMPERATURE) {
                    value_now = y[nxy] = valu_q[qj];
                } else if (ch == PLOT_CH_PRESSURE) {
                    value_now = y[nxy] = valu_q[qj];
                } else if (ch == PLOT_CH_HUMIDITY) {
                    value_now = y[nxy] = valu_q[qj];
                }
                nxy++;
            }
        }

        // x axis depends on time span
        int period_s = x[0];                                    // oldest age first
        const char *xlabel;
        float time_scale;
        if (period_s >= 3600) {
            xlabel = "Hours";
            time_scale = -1/3600.0F;
        } else {
            xlabel = "Minutes";
            time_scale = -1/60.0F;
        }
        for (int j = 0; j < nxy; j++)
            x[j] *= time_scale;
        // Serial.printf ("BME %10ld s %d  %6.2f .. %6.2f\n", readDT/1000, nxy, x[0], x[nxy-1]);

        // prep plot box
        SBox plbox = box;                                       // start assuming whole
        if (getNBMEConnected() > 1) {
            plbox.h /= 2;                                       // 2 sensors so plot must be half height
            if (i > 0)
                plbox.y += plbox.h;                             // second sensor uses lower half
        }

        // plot in plbox, showing a bit more precision for imperial pressure
        if (ch == PLOT_CH_PRESSURE && !showATMhPa()) {
            char buf[32];
            snprintf (buf, sizeof(buf), "%.2f", value_now);
            plotXYstr (plbox, x, y, nxy, xlabel, title, color, 0, 0, buf);
        } else {
            plotXY (plbox, x, y, nxy, xlabel, title, color, 0, 0, value_now);
        }
    }

    // looks better to updatr border immediately
    showRotatingBorder();
}

/* try to connect to sensors, reset brb_mode and brb_rotset to something benign if no longer appropriate
 */
void initBME280()
{
    connectSensors(true);

    if ((brb_rotset & (1 << BRB_SHOW_BME76)) && !bme_data[BME_76]) {
        Serial.print ("BME: Removing BRB_SHOW_BME76 from brb_rotset\n");
        brb_rotset &= ~(1 << BRB_SHOW_BME76);
        checkBRBRotset();
    }
    if ((brb_rotset & (1 << BRB_SHOW_BME77)) && !bme_data[BME_77]) {
        Serial.print ("BME: Removing BRB_SHOW_BME77 from brb_rotset\n");
        brb_rotset &= ~(1 << BRB_SHOW_BME77);
        checkBRBRotset();
    }
}


/* retrieve pointer to the given sensor data if connected, else NULL.
 * make a fresh read if desired.
 * index 0 always for 76, 1 for 77.
 */
const BMEData *getBMEData (BMEIndex device, bool fresh_read)
{
    if (fresh_read)
        (void) readSensor (device);

    return (bme_data[(int)device]);
}

/* take a new reading if it's time.
 * N.B. ignore if no sensors connected or clock not set.
 */
void readBME280 ()
{
    // reset here assuming both pane and BCB boxes had their chance
    new_data = false;

    if (getNBMEConnected() == 0 || !clockTimeOk())
        return;

    uint32_t t0 = millis();

    if (!last_reading || t0 - last_reading >= readDT) {

        // read new values into queues and advance cadence
        if (readSensors()) {

            // gradually slow
            time_t up = getUptime (NULL, NULL, NULL, NULL);
            if (up > SS_START/1000)
                readDT = FINAL_DT;
            else
                readDT = START_DT + up*(1000L*(FINAL_DT-START_DT)/SS_START);
            // Serial.printf ("BME up %d s readDT %ld s\n", up, readDT/1000);
        }
    }
}

/* draw all panes showing any BME data
 */
void drawBME280Panes()
{
    PlotPane pp;

    pp = findPaneChoiceNow (PLOT_CH_TEMPERATURE);
    if (pp != PANE_NONE)
        drawOneBME280Pane (plot_b[pp], PLOT_CH_TEMPERATURE);
    pp = findPaneChoiceNow (PLOT_CH_PRESSURE);
    if (pp != PANE_NONE)
        drawOneBME280Pane (plot_b[pp], PLOT_CH_PRESSURE);
    pp = findPaneChoiceNow (PLOT_CH_HUMIDITY);
    if (pp != PANE_NONE)
        drawOneBME280Pane (plot_b[pp], PLOT_CH_HUMIDITY);
    pp = findPaneChoiceNow (PLOT_CH_DEWPOINT);
    if (pp != PANE_NONE)
        drawOneBME280Pane (plot_b[pp], PLOT_CH_DEWPOINT);
}

/* return whether new data has been read that has not been displayed
 */
bool newBME280data()
{
    return (new_data);
}


/* return number of connected BME sensors.
 * N.B. only valid after connectSensors()
 */
int getNBMEConnected(void)
{
        return ((bme_data[BME_76] != NULL) + (bme_data[BME_77] != NULL));
}

/* draw the BME stats for brb_mode in NCDXF_b.
 */
void drawBMEStats()
{
    // arrays for drawNCDXFStats()
    char titles[NCDXF_B_NFIELDS][NCDXF_B_MAXLEN];
    char values[NCDXF_B_NFIELDS][NCDXF_B_MAXLEN];
    uint16_t colors[NCDXF_B_NFIELDS];

    // get desired data and name
    const BMEData *dp = NULL;
    const char *name = NULL;
    if (brb_mode == BRB_SHOW_BME76) {
        dp = getBMEData (BME_76, false);
        name = "@76";
    } else if (brb_mode == BRB_SHOW_BME77) {
        dp = getBMEData (BME_77, false);
        name = "@77";
    } else {
        fatalError ("drawBMEStats() brb_mode %d no data", brb_mode);
        return; // lint
    }

    // newest data is at head-1
    int qi = (dp->q_head + N_BME_READINGS - 1) % N_BME_READINGS;

    // fill fields for drawNCDXFStats()
    int i = 0;

    snprintf (titles[i], sizeof(titles[i]), "Temp%s", name);
    snprintf (values[i], sizeof(values[i]), "%.1f", dp->t[qi]);
    colors[i] = TEMP_COLOR;
    i++;

    strcpy (titles[i], "Humidity");
    snprintf (values[i], sizeof(values[i]), "%.1f", dp->h[qi]);
    colors[i] = HUM_COLOR;
    i++;

    strcpy (titles[i], "Dew Pt");
    snprintf (values[i], sizeof(values[i]), "%.1f", dewPoint(dp->t[qi],dp->h[qi]));
    colors[i] = DP_COLOR;
    i++;

    strcpy (titles[i], "Pressure");
    if (showATMhPa())
        snprintf (values[i], sizeof(values[i]), "%.0f", dp->p[qi]);        // hPa
    else
        snprintf (values[i], sizeof(values[i]), "%.2f", dp->p[qi]);        // inHg
    colors[i] = PRES_COLOR;
    i++;

    if (i != NCDXF_B_NFIELDS)
        fatalError ("drawBMEStats wrong count");

    // do it
    drawNCDXFStats (RA8875_BLACK, titles, values, colors);
}

/* handle a touch in NCDXF_b known to be showing BME stats
 */
void doBMETouch (const SCoord &s)
{
    // decide which param
    const uint16_t h = NCDXF_b.h / NCDXF_B_NFIELDS;
    int n = (s.y - NCDXF_b.y)/h;

    // list of pane choices
    PlotChoice pcs[NCDXF_B_NFIELDS];            
    pcs[0] = PLOT_CH_TEMPERATURE;
    pcs[1] = PLOT_CH_HUMIDITY;
    pcs[2] = PLOT_CH_DEWPOINT;
    pcs[3] = PLOT_CH_PRESSURE;

    // engage
    setPlotVisible (pcs[n]);
}

/* change the temperature correction for the given BME, both any current data and NV persistent.
 * correction is in current user units.
 */
bool recalBMETemp (BMEIndex device, float new_corr)
{
    // access existing data, if any
    BMEData *dp = bme_data[(int)device];

    if (dp) {
        // compute net change
        float del_corr = new_corr - getBMETempCorr(device);

        // apply to all existing data
        for (int i = 0; i < N_BME_READINGS; i++)
            if (dp->u[i] > 0)
                dp->t[i] = dp->t[i] + del_corr;

        // update display, if any applicable
        drawBME280Panes();
        drawNCDXFBox();
    }

    // persist the new correction. not an error if no existing data.
    return (setBMETempCorr (device, new_corr));
}

/* change the pressure correction for the given BME, both cpurrent data and NV persistent.
 * correction is in current user units.
 */
bool recalBMEPres (BMEIndex device, float new_corr)
{
    // access existing data, if any
    BMEData *dp = bme_data[(int)device];

    if (dp) {
        // compute net change
        float del_corr = new_corr - getBMEPresCorr(device);

        // apply to all existing data
        for (int i = 0; i < N_BME_READINGS; i++)
            if (dp->u[i] > 0)
                dp->p[i] = dp->p[i] + del_corr;

        // update display, if any applicable
        drawBME280Panes();
        drawNCDXFBox();
    }

    // persist the new correction. not an error if no existing data.
    return (setBMEPresCorr (device, new_corr));
}