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    Nicla Sense ME temperature and humidity inaccurate

    olboss
    Member

    Nicla Sense ME temperature and humidity inaccurate

    I have three Nicla Sense ME boards, and on all of them the temperature is about 7.5 degrees too high, and the Humidity is about 22% too low. There is little difference between the native temperature reading and the compensated BSEC output. Adjusting the multiplier in the library to the corrected value also has little effect.

    I've tried running in standalone mode, and as a shield on an Arduino MKR1010. Same result. 

    Attached is a plot from 24h, demonstrating a comparison against a BME280.

    The code running on the Nicla Sense is below.

    Does anyone have any suggestions? And has anyone tested the gas sensor accuracy against a benchmark? I have my doubts, given the strange temperature and humidity readings.

    /*
    *Script to set the NICLA to respond to a wire command and return bsec data
    */
    #include "Nicla_System.h"
    #include "Arduino_BHY2.h"
    #include <Wire.h>

    Sensor temp(SENSOR_ID_TEMP); //!!the library has a multiplier: https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/Use-BSEC-with-BHI260AP-on-Arduino-Nicla-...
    Sensor humi(SENSOR_ID_HUM );
    Sensor baro(SENSOR_ID_BARO);
    Sensor gas(SENSOR_ID_GAS);

    SensorBSEC bsec(SENSOR_ID_BSEC_LEGACY); //it's critical to follow this tip https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BME688-Nicla-Sense-me-how-to-access-the-...

    #define BAUD_RATE_SERIAL_DATA (115200) //To transfer bsec data https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/Nicla-Sense-ME-I2C-Disconnecting-Bug/m-p...

    int sampleInt = 5000;
    unsigned long lastMillis = 0;

    void setup()
    {
    //Serial.begin(115200);
    Serial.begin(BAUD_RATE_SERIAL_DATA);

    BHY2.begin();

    temp.begin();
    humi.begin();
    baro.begin();
    gas.begin();
    bsec.begin();

    nicla::begin();
    nicla::leds.begin();

    Wire.begin(8); // join i2c bus with address #8
    Wire.onRequest(requestEvent); // register event
    }

    void loop()
    {
    int blueOn = 0;
    //static auto lastMillis = millis();

    // Update function should be continuously polled
    BHY2.update(100);

    if ((unsigned long)(millis() - lastMillis) > sampleInt) {
    lastMillis = millis();

    uint32_t eCO2 = bsec.co2_eq();
    if (eCO2 < 800) nicla::leds.setColor(green);
    if (eCO2 >= 800 && eCO2 < 1200) nicla::leds.setColor(yellow); // it's near green, could be optimized
    if (eCO2 >= 1200) nicla::leds.setColor(red);
    blueOn = 0;
    }

    if (millis() - lastMillis > 4000 & blueOn == 0) {
    //blue means its waiting for a new query
    nicla::leds.setColor(blue);
    blueOn == 1;
    }

    }

    void requestEvent() {
    nicla::leds.setColor(magenta);
    String output = bsec.toString();
    char huh[131];
    output.toCharArray(huh, 131);
    Serial.print("Wire sending: ");
    Serial.println(huh);
    Wire.write(huh, 131); // respond with message of 131 bytes
    // as expected by master
    }

     

     
    25 REPLIES 25
    BSTRobin
    Community Moderator

    Re: Nicla Sense ME temperature and humidity inaccurate

    Hello olboss,

    We will update software to improve temperature, humidity accuracy in the future.

    olboss
    Member

    Re: Nicla Sense ME temperature and humidity inaccurate

    That's good news!

    Do you have a timeline for the release of the update?

    Will the accuracy of the gas sensor readings be updated at the same time?

     

     

     

    BSTRobin
    Community Moderator

    Re: Nicla Sense ME temperature and humidity inaccurate

    Hello olboss,

    We will check the timeline and let you know.

    BSTRobin
    Community Moderator

    Re: Nicla Sense ME temperature and humidity inaccurate

    Hello olboss,

    I would like to know  the name that the USB device enumerates. Could you help provide it? Thanks.

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