RFM12Pi and 1-wire using GPIO 4 on the Pi

Hi All,

Just got my emonTX v3 with the RFM12Pi so only just getting started.  I've been using my Pi to monitor several DS18B20 1-wire temperature sensors, since it has 1-wire support on GPIO 4, but the RFM12Pi uses this pin for _RESET.

Does anyone know if we can either switch the Pi to use a different GPIO for 1-wire or if we can still use the GPIO 4 even though it's trying to be a reset to the RFM?

Thanks a lot, Darren

glyn.hudson's picture

Re: RFM12Pi and 1-wire using GPIO 4 on the Pi

The rfm12pi only uses the reset when uploading new firmware code to the atmega328. This is a user initiated process and is a bit of a fallback incase a firmware update was required. We have never needed to update the firmware so this pin can be used for whatever you want although you will need to break to the track on the PCB going to the rest to avoid he the atmega 328 from resetting. It's probably easier to use a different gpio pin for one wire.

dkeverne's picture

Re: RFM12Pi and 1-wire using GPIO 4 on the Pi

Hi Glyn,

Thanks for the info.  I'd read about the RPi software upload and it's good to see you don't need it often, I guess the code in the RFM doesn't need to be changed very often.  I've found a thread on the RPi site about changing the GPIO pin, although it requires recompiling w1-gpio kernel module to make the IO selectable.  I'll give that a go at some point, or use one of the other π's I have.

Working ok so far though, oemgateway up and running :-)


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