Schematic, datasheet default pin mapping etc. can be found over [here](https://docs.electronut.in/papyr/). The default pin mapping can be found in the board directory.
## Installing CircuitPython submodules
Before you can build, you will need to run the following commands once, which
will install the submodules that are part of the CircuitPython ecosystem, and
build the `mpy-cross` tool:
```
$ cd circuitpython
$ git submodule update --init
$ make -C mpy-cross
```
## Installing the Bootloader
If the `Adafruit nRF52 bootloader` is installed on the board, then the
bootloader allows you to update the core CircuitPython firmware and internal
file system contents using serial, or USB CDC, or USB mass storage.
On empty devices, the bootloader will need to be flashed once using a
HW debugger such as a Segger J-Link, or Blackmagicprobe
