ESP8266 + temp sensor fail!

I’ve designed a few sensor boards that collect temperature, humidity, light, sound etc… and send them over wifi, or a local radio network. Recently I switched to the ESP8266, and had my first fail.

The temp sensor was mounted next to the ESP8266, which is fine until you turn everything on, and realise that the ESP gets warm and completely compromises the readings on the temp sensor.

Oops!

Version 1

I designed a second version of the board, with some physical separation between the ESP and the temp sensor, making cuts into the board to stop the heat traveling through to the sensor area.

Version 2

Even with this change we still get heat transfer between the ESP and the temp sensor. Within 10 minutes of power up we have a 4°C rise in temperature readings.

temp

At this point I have a few options

1. Re-design the board, giving even more physical separation between the ESP and the sensors
2. Add a heatsink to the ESP to try and dissipate the heat
3. Modify the software to put the ESP into sleep mode between sensor readings, to reduce heat output

I’ll try a combination of the second two, although ultimately a new board might be the better solution.

4 Comments

  1. Sriram

    Cutouts look great for isolation between the ESP and sensor. I believe it is not the ESP, but it is the regulator.

    Have you checked the linear regulator’s temperature as well?
    Looks like in both cases you have the sensor pretty close to the regulator.

    Try these:
    1. Insert a piece of thermal insulation, like a wall, in the cutout between regulator and sensor.
    2. Add a cut on the bottom copper pour, on the arm close to USB connector.

    -Sriram

  2. lord anubis

    You can also record the time/temp influence. Put that in a table and adjust the temperature in code. If that works, please let us know. I did do that with the TI free dev kits with built in sensor and a external sensor. Came close to -2% to +4%.

  3. Akis

    Hi,
    Maybe is the USB connector. Metal is an excellent heat conductor, and as I seen the connector bridges the two parts of the board.

  4. john

    try to mount the pcb vertically with the temp sensor on the bottom you will get a pretty good measurement 🙂

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