Moteinos with RFM69HW Node/Gateway won't receive

[Tony Weil]

I have 2 Moetino's with RFM69HW 915Mhz. One has Node and the other has Gateway firmware. Both are configured for 915Mhz and RFM69HW high power. When I run the Node and Gateway on the pair, it works great. But if I swap the Node and Gateway software between the 2 devices, the Node sends, but the Gateway never receives. It seems like the receiver is broken on one of the radios. Ideas??

Thanks,
Tony

[WhiteHare]

Just a shot in the dark, but have you confirmed that the power supplies are identical and functioning identically in both cases?  More specifically, does exchanging the power supplies affect which setup is the functional one?

[Tony Weil]

Both Moteinos are using the exact same FTDI Cable for power and serial. I tried dropping the baud rate to 9600, but no luck.

This is probably a red herring, but I tried another setup using the "good" Moteino and a 3.3V Uno Clone with a  standalone 915Mhz RFM69HW connected to the SPI pins, powered by a USB cable connected to the computer.Then I loaded the same Node and Gateway firmware. The Motenio "Node" sends the data correctly, but the Uno "Gateway node starts listening and receives nothing. When I swap the Node and Gateway firmware, the Uno "Node" sends the data correctly, but the Moteino "Gateway receives it correctly. So, the "bad" Moteino and my Uno clone fail in the exact same way. I suppose it is possible that both have a bad MISO connection. I will check that next.

[WhiteHare]

Can you confirm that both your sketches #DEFINE the IS_RFM69HW correctly?  Or is it commented out?  I'm guessing this may be the problem.

[Tony Weil]

Yes, both sketches have #DEFINE the IS_RFM69HW correctly?

I have it all working now, but I'm not exactly sure how and why:

As a test, both Moteinos are powered off an identical USB-FTDI cable that is connected to the same computer supplying  3.3V, GND, and serial connections. At one point, when the communication was not working, I connected the grounds of the two Moteinos and everything started working correctly.

The problem now is that I have removed the extra ground wire and it continues to work, even after disconnecting and powering down everything. I assume if the Moteinos had separate power supplies and grounds as you would in a real usage situation that the grounding would not be an issue.

[Felix]

Having common grounds is not a requirement.

[Tony Weil]

Does anyone have any idea why some of the modules were not receiving consistently, and then all of the sudden it works great? I really did not make any changes to the setup. I want to make sure I understand how all of this works before setting up more home automation. Thanks.

[Felix]

Lots of things can factor into it. But based on experience and what people usually report in the forum, it's usually some user deterministic factor.
Usually software. But commonly also hardware improperly user or wired or soldered, or antennas curled and not kept perpendicular to the GND plane (monopoles), or the boards completely enclosed in metal, things like that. Some basic RF knowledge will help a lot in those scenarios. For most other issues the forum should help, lots of these problems have already been discussed or debugged.