802.15.4 radios running at 2.4GHz seem to work for only short distances in wild locations with trees in the way, so I'd like to make an inexpensive platform for 900MHz/868MHz bands. The mulle platform docs say it is incomplete here: https://github.com/RIOT-OS/RIOT/wiki/Board%3A-Mulle
Are any of the other 2.4GHz ARM platforms easy to change to a 900MHz radio such as AT86RF212b?
What other 900MHz radios should I consider? The ST spirit radio has a contiki driver, but no riot-os.
Is anyone using the NXP/Freescale MKW01 MCU-radio chip?
I have used the Semtech SX127x chip that has the proprietary LoRa chirp spread spectrum modulation (in addition to a few other common modulations, such as FSK). There are plenty of affordable eval boards, such as this:
https://www.tindie.com/products/DORJI_COM/868mhz-915mhz-sx1276-data-radio-modem-drf1276dm/
(Search for other LoRa products, there are eval boards in Arduino, Raspberry Pi and Xbee form factors)
The chip has a 256 byte buffer which accommodates 802.15.4, but has no 802.15.4-specific features such as PAN filtering to reduce CPU load. The chip also has poor timing control of the radio… it’s hard to start a transmission with microsecond control like you can with some TI radios. So it isn’t exactly suitable for a protocol with tight timing control.
The CC1310 MCU+radio seems great for longer range with 40kbps data throughput, and has a relatively short lock time for changing frequencies, so hopping modes should be efficient power wise. Some mention of porting CC1310 has been made here.
CC1120 would be a good choice - although the TI dev boards are the only simple way to prototype
http://www.ti.com/tool/cc1120emk-868-915
we have used them with contiki-6LowPAN over 1km distances
Cheers
Kirk