FONA

[last updated: 2020-03-01]
go to: house alarm project
go to: FONA-1 project page
go to: FONA-2 project page
go to: FONA-2.5 project page
go to: FONA-3 project page
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Current Status: Breadboard circuit with FONA-2 with Mega completely successful as far as tested: SMS send & receive works; NTP time synch works (in spite of not having a GPRS antenna connected). FONA-3 project in progress, not currently functional (Feb 04, 2020)
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The FONA is an Adafruit shield (or breakout) of a cell/GPS chip (808 MiniGSM + GPS).
It's basically a cell phone with GPS on a chip.
I have done three projects using these modules:

"FONA-1" project using the Uno Shield (link to: Adafruit PID: 2636)

FONA breakout (Ada: 2542)

Uno Shield (Ada: 2636)
"FONA-2" project using the Breakout (link to: Adafruit PID: 2542)
"FONA-3" project using the Breakout with two Arduino Teensy's
FONA pinouts and signals

It requires a SiM card to work (must be a "mini"-SIM; "micro"-SIM's won't work):

Every SIM card has an ID, called a ICCID. It is (on mine at least) a 19-digit number, printed on a label on the top (ie. non-contact side) of the SIM card. Record this number, as you will need it to activate your SIM with your cell provider.
IMEI number:
Every phone or Mobile Broadband device has a unique 15 digit code, called an IMEI number.
So both the shield and the breakout will have their own unique IMEI numbers (though more precisely it's the SIM808 module itself that has the IMEI)
When you receive your shield or breakout, copy down the IMEI printed on the SIM808 module, as you'll need to register this number with your cell carrier (Ting in my case) in order to pair (register?) your SIM card with your cell/GPS module.
Slide the SIM card (gold contacts facing down) into the holder:
the holder is on the bottom of the 2542 breakout,
and on the top of the 2636 shield.

The SIM holder is tricky. To open a holder, you must first slide the top section about 1/16" towards its hinge. Then you can swing the top part (that has the slot to actually hold the SIM card) up vertical to insert or remove the SIM. Swing the top part back down, then slide it 1/16" back to lock it.

Click to select the line with the phone number you wish to edit
IMEI field was blank, though it should have been active. Clicked "activate"
enter IMEI. click
enter spam checks, then "check compatibility"
enter ICCID, then what?
both my SIM's were listed as "already active", which indeed they should have been
it said I could manage them on "account control panel", but the link took me to "current usage" where I couldn't verify that the correct IMEI was registered to the correct SIM ICCID.

not sure what's going on, but it appears at the least that the IMEI number is not visible on the Ting site, even after activating and registering.
All that said, it appears to be moot, since both my SIM cards work.

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The Vio pin MUST be attached to an external voltage source from 2.8 to 5v. The voltage you apply to this pin defines the logic level of the communication between the FONA and your microprocessor. If your MPU uses 3v, you must connect the FONA Vio pin to a 3v source.
Connect the shield or breakout to an Arduino (or other micro-controller), and apply power:

Both the Arduino and the FONA must have power applied.
The FONA uses a lot of juice to work reliably. Powering from USB is OK to load the program, but then you must switch to a 3.7v LiPo.

The FONA Key pin will toggle the module power on/off when you connect it to gnd for 2 sec. Tie it permanently to gnd to keep your FONA powered on.
Status LED's:

slow: 64ms on, 800ms off: the module is running but has not made connection to a cellular network
v. slow blink: 64ms on, 3 seconds off: the module has made contact with the cellular network and can send/receive voiceand SMS
fast: 64ms on, 300ms off: a GPRS data connection is active

Orange/Green: (between the micro USB port and the LiPo battery connector)
- Orange: Battery is charging
- Green: Battery is fully charged

Gotcha to watch out for: The uFL antenna connectors on the FONA shield are tiny (= not robust). When you attach the antennas, if the connector on the antenna has gotten bent at all, it is easy to use too much force. Once attached, they are dangling on the ends of their (3 - 6" depending on type) cables, and if you're not careful, you can put so much torque on the antenna connector where it's SMD soldered to the board that you can break it off (don't ask me how I know).

The pin on the FONA labeled Rx is into the module, and Tx is out of the module.
However, the nominal way this is supposed to work is that the MCU Tx sends data to the module Rx. But in an effort to make it "less confusing" for beginners, the Adafruit code (from which I started) reverses those in the SoftwareSerial declaration, so that the FONA_RX pin on the Arduino actually sends data to the FONA module Rx.
If you look at these signals with a scope, the (actual) Tx line is nominally at Vcc, and pulses to gnd when sending data.
The FONA is "auto baud", so whatever baud rate you use to send the first "AT" after reboot will be used for all your serial communication.
"You can use 'any baud rate,' but 9600 is recommended as being compatible with all terminal programs."

(link to:) This Adafruit Tutorial has great tips, including how to connect and exercise the module by direct connecting to a USB port on a PC.

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Unresolved issues:

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Things to do next:

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