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Thread: MLX90614 isuue with Teensy

  1. #1
    Junior Member
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    MLX90614 isuue with Teensy

    Hello,
    I tested MLX90614 with Arduino and it works fine (I used a level shifter for 3-5V as I needed the medical sensor that works only on 3V).

    When I tried the MLX90614 on Teensy 4.0, the address was coming (0x5A) but no data was read at all.

    I used Sparkfun library


    Schematic:

    Click image for larger version. 

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    For reference, this is MLX90614ESF-DCA

    Code is straighforward:

    Code:
    /****************************************************************************** 
    MLX90614_Serial_Demo.ino
    Serial output example for the MLX90614 Infrared Thermometer
    
    This example reads from the MLX90614 and prints out ambient and object temperatures every half-second or so. Open the serial monitor and set the
    baud rate to 9600.
    
    Hardware Hookup (if you're not using the eval board):
    MLX90614 ------------- Arduino
      VDD ------------------ 3.3V
      VSS ------------------ GND
      SDA ------------------ SDA (A4 on older boards)
      SCL ------------------ SCL (A5 on older boards)
      
    An LED can be attached to pin 8 to monitor for any read errors.
    
    Jim Lindblom @ SparkFun Electronics
    October 23, 2015
    https://github.com/sparkfun/SparkFun_MLX90614_Arduino_Library
    
    Development environment specifics:
    Arduino 1.6.5
    SparkFun IR Thermometer Evaluation Board - MLX90614
    ******************************************************************************/
    
    #include <Wire.h> // I2C library, required for MLX90614
    #include <SparkFunMLX90614.h> // SparkFunMLX90614 Arduino library
    
    IRTherm therm; // Create an IRTherm object to interact with throughout
    
    const byte LED_PIN = 8; // Optional LED attached to pin 8 (active low)
    
    void setup() 
    {
      Serial.begin(9600); // Initialize Serial to log output
      therm.begin(); // Initialize thermal IR sensor
      therm.setUnit(TEMP_F); // Set the library's units to Farenheit
      // Alternatively, TEMP_F can be replaced with TEMP_C for Celsius or
      // TEMP_K for Kelvin.
      
      pinMode(LED_PIN, OUTPUT); // LED pin as output
      setLED(LOW); // LED OFF
    }
    
    void loop() 
    {
      setLED(HIGH); //LED on
      
      // Call therm.read() to read object and ambient temperatures from the sensor.
      if (therm.read()) // On success, read() will return 1, on fail 0.
      {
        // Use the object() and ambient() functions to grab the object and ambient
    	// temperatures.
    	// They'll be floats, calculated out to the unit you set with setUnit().
        Serial.print("Object: " + String(therm.object(), 2));
        Serial.write('°'); // Degree Symbol
        Serial.println("F");
        Serial.print("Ambient: " + String(therm.ambient(), 2));
        Serial.write('°'); // Degree Symbol
        Serial.println("F");
        Serial.println();
      }
      setLED(LOW);
      delay(500);
    }
    
    void setLED(bool on)
    {
      if (on)
        digitalWrite(LED_PIN, LOW);
      else
        digitalWrite(LED_PIN, HIGH);
    }
    Help is appreciated.

  2. #2
    Senior Member+ mjs513's Avatar
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    As a quick suggestion try adding Wire.setClock(100000); after temp.begin(). The other possibility is that the pullups should be reduced to 2.2K's

  3. #3
    Junior Member
    Join Date
    Aug 2019
    Location
    Miami, United States
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    Quote Originally Posted by mjs513 View Post
    As a quick suggestion try adding Wire.setClock(100000); after temp.begin(). The other possibility is that the pullups should be reduced to 2.2K's
    Thanks for your response. The address is successully read using I2C scanner (0x5A) so I believe the I2C speed or the pull ups are the issue.

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