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Thread: MLX90640 Connected to Teensy 3.2

  1. #1
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    MLX90640 Connected to Teensy 3.2

    Hi !

    I have connected the MLX90640 110 degree FOV module to the Teensy 3.2 as suggested in the link below.

    https://learn.sparkfun.com/tutorials...0-hookup-guide

    I then tested it with both Example 1 and Example 2 codes found in the above link. It worked the first few times but then started showing the following error on the serial monitor view.

    "MLX90640 not detected at default I2C address. Please check wiring. Freezing."

    I then added 2.2k pull-up resistors to SCL and SDA pulling it up to 3.3V.

    Again, I was able to get an output on the serial monitor but then after some time I started getting the same error as above.

    Basically I am trying to obtain the temperature data of each pixel of the MLX90640 module on the serial monitor.

    I tried connecting the camera module to the teensy via the qwiic cable and also by soldering pin headers. Both worked at some point until it just didn't anymore.

    I am a little stumped cause it works perfectly and then just stops working without me making any changes. Any suggestions would be greatly appreciated.

  2. #2
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    I have the exact same problem with Teensy 3.6. Have you gotten it working? I think the pull up resistors are included.
    Last edited by white; 12-02-2019 at 05:45 PM. Reason: typo

  3. #3
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    Try lowering the I2C rate to 100000 and/or try the alternate Wire library as a test, as for the wiring we can only assume you followed the site but we can't physically see that until you post pictures

  4. #4
    Senior Member+ mjs513's Avatar
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    As @tonton81 suggested not sure if you have your connections correct but another sure way to test is to run a I2C scanner. If it comes back with the I2C address of the device you know you have it hooked up correctly.

  5. #5
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    I have run an I2C scanner, and could not detect the sensor. Supply voltage is good at 3.3V. I will try lowering I2C rate.

  6. #6
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    I also noticed that the SDA and SCL are shorted to ground when the sensor is not connected. Is this normal?

  7. #7
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by white View Post
    SDA and SCL are shorted to ground when the sensor is not connected. Is this normal?
    No, that's definitely not normal. If you have 2.2K pullup resistors (as mentioned in msg #1), both SDA and SCL should measure 3.3V.

  8. #8
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    I was working with the sparkfun MLX90640. Couldn't make it work no matter what I did. I tried a new module with the Teensy 3.5 and it still didn't work. Tried the exact same thing with the Pimoroni MLX90640 and it worked perfectly. I can only assume the problem is with the Sparkfun camera module.

  9. #9
    Senior Member+ mjs513's Avatar
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    @Sam_in

    Quick question did you still use the Sparkfun library?

  10. #10
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    @mjs513

    I used the MLX90640 library. Yes.

    The same code found here : https://learn.sparkfun.com/tutorials...0-hookup-guide

  11. #11
    Senior Member+ mjs513's Avatar
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    ok - thanks - Reason I asked is that I ordered one of the sparkfun boards and should have it today.

  12. #12
    Senior Member+ mjs513's Avatar
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    Just received my MLX90640 110FOV from sparkfun. Hooked it up to a Teensy 4.0 and a Teensy 3.5. In both cases it showed temp data and using the processing sketch it showed the thermal image as expected. Not very fast but haven't tried adjusting any parameters yet.

    I did use the QWIC connector direct to SDA/SCL/3.3v/Gnd. No pullups for the T3.5 or the T4.0. Looking at the schematic it has 2.2K pullups already on the breakout board.

  13. #13
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    Quote Originally Posted by mjs513 View Post
    Just received my MLX90640 110FOV from sparkfun. Hooked it up to a Teensy 4.0 and a Teensy 3.5. In both cases it showed temp data and using the processing sketch it showed the thermal image as expected. Not very fast but haven't tried adjusting any parameters yet.

    I did use the QWIC connector direct to SDA/SCL/3.3v/Gnd. No pullups for the T3.5 or the T4.0. Looking at the schematic it has 2.2K pullups already on the breakout board.
    Even mine worked on the first attempt but stopped working after some time. I tried with and without the pull up resistors. Please do let us know if it stops working.

  14. #14
    Senior Member+ mjs513's Avatar
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    Just a quick status. Left it on for 4 hours last know. PC went to sleep. When I woke it up it was still running and spewing data. The processing sketch picked up as well.

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