M5StickC and Grove-Temperature_Sensor_V1.2



  • I bought the Grove-Temperature_Sensor_V1.2 and connected to M5StickC. I copied almost all the code from the Seedstudio page (https://wiki.seeedstudio.com/Grove-Temperature_Sensor_V1.2/#software) to convert the analog read to actual temperature, only adding the #include <M5StickC.h> and the M5.begin, but the temperature is way off and very oscillating. I am using pin 32 to read the data, Is it correct? Is it a sensor issue?

    For example, a sample output is:

    -0.34
    -2.32
    -4.34
    -2.16
    -3.89
    -4.04
    -3.42
    -5.16
    -4.42
    -4.79
    -5.24
    -5.09
    -5.38
    -6.61
    -6.40
    -5.82
    -6.96
    -6.82
    -6.96
    -6.89
    -6.96
    -7.17
    -6.96
    -8.08
    -6.96
    -6.96
    -7.94

    And the code is:

    #include <M5StickC.h>
    #include <math.h>

    const int B = 4275;
    const float R0 = 100000;
    const int PIN = 32;

    void setup() {
    M5.begin();

    Serial.begin(115200);

    }

    void loop() {

    int a = analogRead(PIN);

    float R = 1023.0/a-1.0;
    R = R0*R;

    float temperature = 1.0 / (log(R / 10000.0) / B + 1 / 298.15) - 273.15;

    Serial.println(temperature);

    delay(500);
    }

    Thanks,
    Fernando Gonzalez Sidders



  • @fsidders I fixed the code, changed 10000 to 100000 in temperature formula, but the temperature is still off and oscillating:

    #include <M5StickC.h>
    #include <math.h>

    const int B = 4275; // B value of the thermistor
    const float R0 = 100000;
    const int PIN = 32;

    void setup() {
    M5.begin();
    Serial.begin(9600);

    }

    void loop() {

    int a = analogRead(PIN);

    float R = 1023.0/a-1.0;
    R = R0*R;

    float temperature = 1.0/(log(R/R0)/B+1/298.15)-273.15; // convert to temperature via datasheet

    Serial.println(temperature);
    delay(500);
    }

    The temperature displayed now is:

    42.42
    44.15
    42.42
    42.85
    42.96
    45.96
    46.07
    44.38
    44.15
    42.74
    43.50
    42.42
    44.15
    44.49
    42.42
    45.16
    49.58
    42.85


  • M5Stack

    i have check the prodcut document.then i find this information, i guess this sensor need calibration:
    Nominal B-Constant: 4250 ~ 4299K

    if still can't work normal. maybe you could try to contact seeed store

    https://wiki.seeedstudio.com/Grove-Temperature_Sensor_V1.2/#specifications