Weird spikes with MLX90614

[madmaz999]

I am testing the MLX90614 with an arduino mega board in Labview. I have no idea where these spikes are coming from.

Heres the Arduino code I am using

#include <i2cmaster.h>

void setup(){

          Serial.begin(9600);

          Serial.println("Setup...");

          i2c_init(); //Initialise the i2c bus

          PORTC = (1 << PORTC4) | (1 << PORTC5);//enable pullups

}

void loop(){

    int dev = 0x5A<<1;

    int data_low = 0;

    int data_high = 0;

    int pec = 0;

    i2c_start_wait(dev+I2C_WRITE);

    i2c_write(0x07);

    // read

    i2c_rep_start(dev+I2C_READ);

    data_low = i2c_readAck(); //Read 1 byte and then send ack

    data_high = i2c_readAck(); //Read 1 byte and then send ack

    pec = i2c_readNak();

    i2c_stop();

    //This converts high and low bytes together and processes temperature, MSB is a error bit and is ignored for temps

    double tempFactor = 0.02; // 0.02 degrees per LSB (measurement resolution of the MLX90614)

    double tempData = 0x0000; // zero out the data

    int frac; // data past the decimal point

    // This masks off the error bit of the high byte, then moves it left 8 bits and adds the low byte.

    tempData = (double)(((data_high & 0x007F) << 😎 + data_low);

    tempData = (tempData * tempFactor)-0.01;

    float celcius = tempData - 273.15;

    float fahrenheit = (celcius*1.8) + 32;

    Serial.println(celcius);

    delay(250); // wait a second before printing again

}

This is the image of the sketch in Labview

If anyone has an idea what is causing this then please help! Thanks!!!

[madmaz999]

I seen a video here http://www.youtube.com/watch?v=XTmQ0PhJnss

Maybe this is caused by not having a capacitor in place?

[Kaung05]

Hey Madmaz,

I am having the same exact problem here too. I am using ADT7420 temp sensor with arduino Uno. I am trying to plot the temperature from the sensor on LabVIEW and it just gives me spikes like those...

Don't know whether you have found the solution yet but I am still looking for one.

I guess it is somehow the serial connection between Arduino and LabVIEW, not needing a capacitor.