Auxiliary Thermistors/Sensors

  • Howdy!

    I'm starting to design my first homebrew delta (built a kit, don't like it, used lots of Cartesian machines, got bored) and I really like the Duet board. I'm having some trouble figuring out if I can do a few things though…

    I'd like to add some spare temperature sensors (Ideally RTDs) around the printer, say on a power supply, the hot end heat sink, motors, etc. I'd also like to have the possibility to add some current sensing for things like hot ends, bed heaters, power supplies. It seems like the Duet has the spare I/O I'd need to make it work, but I'm wondering what's supported in the firmware or what I might have to hack together to make it work.

    I don't mind modifying the firmware if I have to, but for compatibility, I'd love to avoid it.

    Also I'd just like to say I saw the work y'all are doing with the Delta and the PCB effectors and I'm quite jealous. Looks great.

  • administrators

    Regarding temperature monitoring, you can install 2 RTD daughter boards on the Duet WiFi/Duet Ethernet, giving you 4 temperature channels plus the 3 thermistor channels including the bed thermistor. You can configure dummy tools that use non-existent heater numbers, so that the temperatures will be displayed in DuetWebControl and in PanelDue. You can also configure fans to be controlled thermostatically by the temperature readings associated with those dummy heaters.

    If you want to add current sensing, you would need to modify the firmware and DWC in order to display the result.

    HTH David

  • Thanks for the info!

    I noticed that the RTD boards are using SPI, is the two board limit just because of the available CS lines on the main board? It looks like there are a few more CS lines available on the expansion header I could use as well.

    I'm definitely going to put a hold on the current sensing for now. I have enough to do just trying to get a functional delta built and calibrated. Can come back to the fancy stuff later…

  • administrators

    Yes there are another 4 CS lines on the expansion bus, allowing a total of 4 daughter boards to be used.

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