The RFM12B radio transceiver module for 434 MHz and 915 MHz bands is very interesting, especially due to the very low price given the capabilities (as I understand them).
I'm not sure I really understand the device, though. For example, on page 5 of the programming manual at http://www.hoperf.com/upfile/RF12B_code.pdf there is a register call "Synchron Command" which is "used to reprogram the synchronic pattern;" (sic). What is a synchron pattern; is that explained anywhere?
Also, according to the "wake up timer command" described on page 7 the wake-up period is Twake-up = M * 2^R [ms]. I assume [ms] means milliseconds. The register map shows 8 bits for M and 5 bits for R. So with all those bits high, your maximum wakeup time should be 255 * 2^31 milliseconds, which is 5.476E11 msec, or just over 17 years. Really? Did they test that? :-)
Since there is a wake up timer, apparently there is a sleep mode. Is that explained anywhere? Thanks for any assistance!