DHT 22 I/O error on Duet 3MB6HC



  • Hi,

    I'm working on integrating the Duet 3 MB6HC board into my 4th printer (ran duet 2 wifi + duex5 on past builds) . For some unknown reason, I am repeatedly seeing error messages when trying to setup a DHT22 into the system:
    Sensor 3 (Chamber Temp) type DHT-temperature using pin io6.in, reading 2000.0, last error: sensor I/O error, sensor type DHT22
    M308 S4
    Sensor 4 (Chamber Hum[%]) type DHT-humidity, reading 2000.0, last error: success, additional output 1 of sensor 3

    I'm running 3.2-beta2 on the board in standalone mode (without a pi). My config.g code is:
    M308 S3 P"io6.in" Y"dht22" R2200 A"Chamber Temp" ; define DHT22 temperature sensor
    M308 S4 P"S3.1" Y"dhthumidity" R2200 A"Chamber Hum[%]" ; Attach DHT22 humidity sensor to secondary output of temperature sensor

    In terms of connections, I've tried io5.in, io6.in and SPI.CS1 on the TempDB pins. I've also tried to power the DHT22 with 5v and 3.3v although only 3.3v while plugged into CS1 as I'm not sure if 5v would fry the pin. I've also tried with and without an explicit R value, using a 2.2k Ohm pullup resistor going into the DHT22 and using a "0." at the start of the pin name as per a forum post I read but still nothing...

    I have no idea what I'm doing wrong as I've used a ton of these sensors for arduino projects in the past. Any help would be greatly appreciated.


  • Moderator


  • administrators

    Use either a CS pin or an io#.out pin, with a 4K7 pullup resistor to +3.3V, and 3.3V power. The io#.in pins are not suitable.



  • @dc42 4.7k ohm pullup resistor on CS1 worked, thanks for your help!


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