I learned a number of things when I was trying this out.
First, the Firmware update utility in emonCMS Admin > Update > Update Firmware Only is great. Nice work, OEM team!
This Firmware update utility works really well to switch your RFM69Pi between the JeeLib Classic and LPL firmware.
The Firmware update utility doesn’t currently work to update the firmware in an attached USB device such as a Moteino. There are two reasons for this.
The RFM69Pi update script is hardcoded to work with the GPIO. There’s a clever script that overrides the reset to use GPIO pin 7 on the Pi.
The firmware used by the script is a binary that is compiled for RFM69Pi with its 8mhz internal clock. That’s not an Arduino-compatible board like the Moteino USB, so the .hex firmware is not compatible, even though the source sketch is. So as things stand, the way I would suggest you flash the Moteino firmware is to plug it into your Arduino IDE.
If you want to get the source code from the same place the firmware update script is grabbing it, you can look in /opt/openenergymonitor/EmonScripts/firmware_available.json and find the corresponding repository in the “download_url”.