I knew that the adafruit Feather Fona is small but being so tightly packed was a surprise.
The Feather Fona is basically a SIM800H GSM modem, an Atmel 32u4 and a LiPo charger all packaged in an arduino compatible manner and all on one board.
The heart of the Fona (which is a small mircacle to me): It sports a 2G GSM modem, Bluetooth, FM-Radio, SMS, Voice-Audio and a TCP/IP Statck – all in one chip. The spec sheet has 380 pages full of AT Commands to keep you busy for a while 🙂
However I can’t recommend to buy this board. There seems to be some major hardware design flaws. On the official adafruit forums are a number of people fighting random resets because the GSM antenna seems to have too much power for the tiny board. Another user reported 9 out of 22 Fonas had faulty SIM-Card holder which he fixed with some tape. I assume that’s the reason why this unit is currently out of stock.
My unit kept resetting after i plugged in the Featherwing (a small 128×32 OLED) and the battery, thus powering the SIM800 chip. Without battery and powered down SIM800 the board worked flawlessly. Without the Featherwing but with battery I was able to place calls. Both together did not work. Even attaching some extension cables to the featherwing didn’t do the trick.
I deactivated the GSM modem, plugged in the OLED and started working on the other parts of the project.
Yesterday I gave it another try and all worked flawlessly. But I don’t know if i would trust a cell phone that may reset at any given time.
However the bigger brother – the FONA (without the feather) doesn’t seem to have these problems. So do yourself a favour and buy thius until adafruit releases a v2.