Start with RFM69 radio module and Arduino Pro Micro as gateway
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Today ordered some parts for this project. I'm now using the NRF024 radio modules but have range issues. There are a lot of dead spots in my house, could be because I have concrete floors and walls. Also there are a lot of fake NRF modules arround,so changes are I have them also. The RFM69 does look better using the 868 Mhz band and not being copied so much.
My plan is to use a 3.3V/8Mhz Arduino Pro Micro as USB gateway on my Domoticz system, this module has the USB port build in and works on 3.3V so no level shifting is needed. Did read that it might be a challenge to get this module working, it has the mega32U4 micocontroller. Maybe there are others who also want to use the Pro Micro so I will post updates in this topic. Waiting for the parts now.
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U could also use a Nano clone for about $3 - $4. Also with USB (and the clones have a CH340 which works out of the box with Linux).
I myself used a Moteino USB from LowPowerLab. Costs a bit more but works like a charm.But do try with the mega32U4! That will interest a lot of people. I think some of the developers are working on 32U4 support!
Good luck!
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Yes, a Nano would do but then I would need level shifting, the RFM69 is not 5V tolerant. And the 3.3V output on the Nano comes from the usb-serial chip (the CH340) and is not a good powersupply, so an extra 3.3V low drop regulater is needed. With the Pro Micro I would need less parts, has full 3.3V design and the unit will be smaller, although size is not really an issue. And it's fun to see if I can get it working.
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Crap! You're right! Moteino still stands though!
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I can't even get the RFM69HW working on my nano's (with shifter & regulator). On 3.3v pro mini's they worked fine. So i just use an arduino pro mini with ftdi adapter. Cheaper than the monteino's.
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My cheap Aliexpress Nanos have MISO and MOSI inverted, just swap the wires between and should work. Also use a decent level converter for all 5 channels (MISO, MOSI, SCK, NSS, DIO0).
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u can use this trick to use usb power
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Ok, I think the project using the Pro Micro ends here. I did some testing (with NRF024 radio module) and I got it working. But the switching of USB ports (bootloader/serial port) is to much hassle. Very tricky to read the serial debug data because after each reset the serial port is unloaded and loads again, giving my serial program a "port not found ", the classis chicken-egg situation. I will switch over to the RFM69 radio module, but no Pro Micro.
