MLX90614 temperature 1037

[LaurB]

Hi, I'm having problems with the MLX90614 sensor. Temperature readings are 1037.55. I have tried using 100kHz and 400kHz I2C speed, the result is the same.

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160566 : Info  : MLX90614  : Temperature: 1037.55
160604 : Info  : MLX90614  : Temperature: 1037.55
170566 : Info  : MLX90614  : Temperature: 1037.55
170603 : Info  : MLX90614  : Temperature: 1037.55
180567 : Info  : MLX90614  : Temperature: 1037.55
180604 : Info  : MLX90614  : Temperature: 1037.55

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The sensor seems to be ok, I tried it on an Uno and the readings are ok.
I'm using ESP_Easy_mega_20201016_normal_ESP8266_4M1M binary file on a Wemos D1.

Any ideas?
Thank you!

[LaurB]

I forgot to mention that the I2C scan detects the sensor.

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I tried with a NodeMCU, the same results.

[Ath]

You don't have other sensors attached? (The screenshots are very minimal)

[LaurB]

Only one MLX is attached

Task 1

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Task 2

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[TD-er]

Hmm can you attach another sensor on the I2C bus so maybe that one has internal pull-up resistors?
Or maybe you can set the boot state of the I2C pins to be using the ESP's internal pull-up resistors? (since the Arduino sketch does seem to work)

I notice there is no I2C address setting in this plugin, but in the past I've seen some (older) plugins that may use the "port" setting also as an offset for the I2C address.
Maybe you need to adapt the port value to make it use the correct I2C address.

[LaurB]

The sensor isn't showing on the i2c scanner anymore and it's not working with Uno either. I think that the problem was the sensor from the start.
Unfortunately I don't have another one to replace it.

[Ath]

You can try to add a couple of pull-up resistors to the I2C bus (by default D4 & D5), then do an I2C scan again to see if that helped in making it work again.

[LaurB]

You can try to add a couple of pull-up resistors to the I2C bus (by default D4 & D5), then do an I2C scan again to see if that helped in making it work again.

I tried with two 2k2 resistors, no luck.
The sensors is mounted on a small pcb and it looks like it has it's own resistors.

20201017_194217.jpg (95.72 KiB) Viewed 9390 times

I uploaded an i2c scanner on an Uno and it didn't detected nothing.

[Ath]

Is that sensor compatible with 5V? As you connected it to an Arduino, that mostly use 5V logic, you may have broken it if it only supports 3.3V...

The on-board I2C pull-up resistors you can check/measure out with a simple multimeter.

[Ath]

I notice there is no I2C address setting in this plugin, but in the past I've seen some (older) plugins that may use the "port" setting also as an offset for the I2C address.

The address is 0x5A by default, where the unit number is added to:

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      byte unit       = CONFIG_PORT;
      uint8_t address = 0x5A + unit;

No clue on how to change the address of the device though.

[LaurB]

3 volt logic.
Stupid mistake.