Using RFM22B revison 3 modules and an ATmega88, I managed to get the example code in EWS_RFM22B_CHAT_EXAMPLE to work.
The following were in the EWS_RFM22B_CHAT_EXAMPLE code. However, they are marked as reserved in the RFM22B datasheet and AN440.pdf from SiliconLabs. I found that only (0x6A, 0x0B) was required for the system to work.
write(0x56, 0x01); // reserved
write(0x58, 0x80); // reserved
write(0x59, 0x40); // reserved
write(0x5A, 0x7F); // reserved
write(0x68, 0x04); // reserved
write(0x6A, 0x0B); // reserved, BUT needed to work!!
Where is the documentation that would enable one to program these "reserved registers"?