Use of linear output temperature sensors



  • I am looking to set up my Duet to monitor a non-contact temperature sensor that outputs 0-5v. There is a linear relationship between temperature and output.

    As I understand it, Duet can only currently monitor thermsitors, thermocouples, and RTD style temperature sensors. I believe the RTD comes the closest, but cannot use variables to modify the output like thermistors can.

    Thus I think my only option will be to modify the source code to add the conversion equation for my sensor. If this is correct, then any insight into where the ideal place to make this revision would be is appreciated. Otherwise I'll continue exploring the code and making sense of it.

    Thanks!
    Mike


  • administrators

    We implemented something similar for an OEM last year for a sensor with a current loop output and created a custom daughter board. It had a precision voltage reference and a 12-bit ADC with SPI interface. The code to support it is included in the standard build of RRF as sensor type 300, in file RepRapFirmware/src/Heating/Sensors/CurrentLoopTemperatureSensor.cpp.



  • Perfect, thanks for clarifying.

    As someone else noted the MCP3204 looks to be the chip you're referring to.

    And the code is here: https://github.com/dc42/RepRapFirmware/blob/6b835cb3c8e9aa10113ae750151d9f9065116cd4/src/Heating/Sensors/CurrentLoopTemperatureSensor.cpp#L23
    I'll report any more findings as I implement.


 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.