Detect if DIO5 isn't correctly mapped (default level != high), warn and disables the channel.
Detect if the RFM isn't responding (reg 0x42 == 0x00), warn and disables the channel.
Warn if both receivers are disabled or unconfigured.
Neither check is foolproof, but they provide a level of detection suitable for most error cases (RFM not installed / DIO5 wrongly mapped to empty pin).
Neither check is foolproof, but they provide a level of detection suitable for most error cases (RFM not installed / DIO5 wrongly mapped to empty pin).