Bluetooth SPI link to temperature sensor daughter boards?

  • Hi folks,
    Currently my polar printer bed uses a stand alone temperature controller powered via a rotating slip ring but I'd like to be able to at least monitor the temperature with the duet. Is it possible to use a pair of spi Bluetooth modules to make a wireless bridge between a temp daughter board and the Duet2 Ethernet?

    Any constructive thoughts would be much appreciated...

    Many thanks
    Barry M

  • You've got two options, get a pair nrf82-something and try to write a spi slave and master to mimmic the temperature daughter board and relay the temperatures over bluetooth from the real board. The hardware is relatively esay, the software side less well documented on the internet, but some should actually work with platformio i think.

    Alternatively two arduinos and two serial bluetooth modules, arduino to mimmic the spi slave daugtherboard, talk to the other arduino over the serial bluetooth link which in turns, as a spi master, talks to the real spi slave and relays the temperatures.

    (3rd option could be to skip the spi slave and use a pwm output with a low pass filter to make an analoge voltage to feed into a regular thermistor input, but likely loss of precision and more noise)

  • The idea of the two arduino boards crossed my mind too as that'd also allow me to also pass the pwm for temperature control to the bed arduino which could mange the bed remotely.

    Was thinking the easier first step would just be a transparent Bluetooth spi link.

    Food for thought!

  • All things being equal it won't be all that different, but you'll find much more examples and support for arduino than the bluetooth chips. Its been a while since I tried* and failed to set up a toolchain for the nrf-something, but now that platformio supprt nrf51/52 that should be greatly simplified.

    *) admittedly not very hard.

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