4 Thermistors on Duet 3 mini?
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Is it possible to connect 4 thermistors to the Duet 3 mini? I have a pinda temp and chamber temp sense required. I did this in the past on a Duet 2 via expansion I/Os.
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@bubblevisor the official recommendation would be to use a PT100 daughterboard and use a PT100 sensor for one of the temperatures you need to monitor.
It may work "OK" using one of the analog inputs on the IO headers however the accuracy will be worse, and it may be nosier than using a proper temperature input, because the temperature inputs are referenced against analog ground and analog VDD and we measure those voltages to improve accuracy. That might be ok for the chamber heater.
On the mini 5+ you will need to use io3.in:
https://duet3d.dozuki.com/Wiki/Duet_3_Mini_5plus_Hardware_overview#Section_IO_port_pin_capabilities
as that is the only IO pin that is analog capable.Also, unlike the temperature inputs, that are pulled up to VDDANA with 2k2, the IO input is pulled up to EXT3.3V with 27k so a temperature setup string needs to take that into account.
This might work for a 100K thermistor
M308 P"io3.in" Y"thermistor" T100000 Bnnnn R27000Where Bnnnn refers to the beta value of that thermistor.
The thermistor would then be connected between IO3.in and Gnd.
Note I have not tried this so don't know if it will work ok.
