Note this is the supply of the PCB only, you will need to supply your own XIAO and RFM9X modules, wires, solder, and other components. An assembled PCB is shown in the images for illustration only.

Board size is 41mm x 19mm.

This circuit board allows you to very easily build a compact long-distance transmitter and receiver for LoRa using a small number of components. The board is powered by the Seeeduino XIAO SAMD21 which are tiny, powerful, and low-cost microcontroller with plenty of memory that you can program with the Arduino IDE.

There are example Arduino programs in the board repository showing how to use the board for LoRa communications, as a GPS tracker, and test programs for wakeups, displays, and GPSs.

The XIAO and RFM9X modules are surface mounted on either side of the PCB so reasonable soldering skills are needed. There is very little other assembly to do, just solder some wires and maybe pin headers and you can be done.

There are connectors on the board for a battery and for external digital IO, I2C, and Serial UART devices. The documentation repository has Arduino sketches for using the board as a very compact GPS tracker transmitter or receiver with OLED display. Also examples for using a BME280 for remote temperature, pressure and humidity monitoring.

You can fit a reverse supply protection diode for the battery connection but it's not mandatory. There are I2C pull up resistors that can be fitted for external I2C devices, but these are often not necessary. On one IO pin you can fit a resistor for driving an external LED or or use a pair of resistors for as a voltage divider and read external voltages.

The board can also be used as a very low power easy to build TTN or LoRaWAN node sensor node. A test sketch for a BME280 sensor node is in the device repository.

You need to check that you can program the Seeeduino XIAO board with the Arduino IDE before soldering it to this PCB. For details on how to install the Arduino IDE for the XIAO see the Seeeduino provided documentation.