After soldering headers to the FONA module, plug it into a breadboard. We'll use an UNO, other Arduinos may be different
- Vio connects to 5V (or, with a 3V logic Arduino, 3V)
- GND connects to GND
- Key connects to GND (always on)
- RX connects to digital 2
- TX connects to digital 3 (9 on Leo/Micro, 10 on Mega)
RST connects to digital 4
Make sure a full LiPo battery is connected!
We'll be using software serial to talk to the module. The Mega ('2560 based) can't use Digital 3 for FONA TX, so use digital 10 instead. The Leonardo and Micro ('32u4 based) can't use digital 3 for FONA TX, so use digital 9 instead. See this page for other pins you can use for FONA TX (SoftwareSerial Receive) on the Mega, Leonardo, and Micro.
You can also try hardware serial, you'll need to update the sketch to indicate which Serial port you want to use