Add developer setup guide

Explain how to set up a development environment to work on this example.

Author: Patater

Diff for: ATCRYPTOAUTH-XPRO-B-K64F2.jpg

@@ -0,0 +1,92 @@
+### Install mbed-cli to a venv
+
+Install mbed-cli to a virtual environment, so that all the things mbed-cli
+installs automatically don't interfere with other things you have installed as
+part of your main environment (which may be managed by your package manager,
+etc.).
+
+```sh
+virtualenv venvs/mbed
+source ~/venvs/mbed/bin/activate
+pip install mbed-cli
+```
+
+### Install the GCC_ARM toolchain
+
+We'll install arm-none-eabi-gcc to `/opt`. You may want to use `~/.local` or
+some other place. Where doesn't matter too much, so long as its in your `$PATH`.
+
+```sh
+wget -q https://developer.arm.com/-/media/Files/downloads/gnu-rm/5_4-2016q3/gcc-arm-none-eabi-5_4-2016q3-20160926-linux.tar.bz2 -O gcc-arm-none-eabi-5_4-2016q3-20160926-linux.tar.bz2 && tar -xjf gcc-arm-none-eabi-5_4-2016q3-20160926-linux.tar.bz2 -C /opt
+rm gcc-arm-none-eabi-5_4-2016q3-20160926-linux.tar.bz2
+```
+
+Remember to add `/opt/gcc-arm-none-eabi-5.4-2016q3/bin` to your `$PATH`.
+
+### Install the ATECC608A example
+
+```sh
+git clone git@github.com:ARMmbed/mbed-os-example-atecc608a.git
+cd mbed-os-example-atecc608a/
+source ~/venvs/mbed/bin/activate
+mbed new .
+mbed deploy
+mbed compile -t GCC_ARM -m K64F --flash --sterm
+```
+
+### PSA Crypto driver development
+
+Add any driver files (none created so far) to the mbed-os-atecc608a folder. It
+is backed by the
+[mbed-os-atecc608a](https://github.com/ARMmbed/mbed-os-atecc608a/tree/mbed-cryptoauthlib)
+repo, which any application wanting to use Mbed OS and the ATECC608A will
+depend on (same as how this example depends on it).
+
+Any Mbed Crypto changes needed to support your driver work should be done in
+`mbed-os/features/mbedtls/mbed-crypto/importer/TARGET_IGNORE/mbed-crypto`, and copied
+into Mbed OS's idiosyncratic file layout before use using the importer.
+
+For the first-time setup only, if you need to make any Mbed Crypto changes,
+perform the following operations:
+
+```sh
+cd mbed-os/features/mbedtls/mbed-crypto/importer
+make update
+```
+
+For every change you make in Mbed Crypto (which you'd make inside
+`mbed-os/features/mbedtls/mbed-crypto/importer/TARGET_IGNORE/mbed-crypto`),
+update Mbed OS with those changes by performing the following operations.
+
+```sh
+curdir=`pwd`
+cd mbed-os/features/mbedtls/mbed-crypto/importer
+make
+cd $curdir
+```
+
+If you don't like having multiple copies of mbed-crypto or mbed-os lying
+around, feel free to make symlinks or git worktrees as desired.
+
+### Hardware interface
+
+There are a couple of evaluation and development kits available for ATECC508A.
+For interfacing with an Mbed platform I2C and power supply connections have to
+be made. Note that ATECC508A requires a 5V supply. Below is an example of
+connecting an
+[ATCRYPTOAUTH-XPRO-B](http://www.microchip.com/DevelopmentTools/ProductDetails.aspx?PartNO=ATCRYPTOAUTH-XPRO-B)
+([header](http://ww1.microchip.com/downloads/en/DeviceDoc/CryptoAuth-XPRO-B_design_documentation.pdf))
+and a K64F:
+
+![ATCRYPTOAUTH-XPRO-B-K64F](ATCRYPTOAUTH-XPRO-B-K64F2.jpg)
+
+For secure connections a shield can be prepared with ATCRYPTOAUTH-XPRO-B. Most
+Mbed platforms support Arduino headers and an [Arduino
+shield](https://store.arduino.cc/usa/arduino-mega-proto-shield-rev3-pcb) can be
+used to prepare a shield for connecting ATCRYPTOAUTH-XPRO-B to an Mbed
+platform. See below image showing ATCRYPTOAUTH-XPRO-B on an Arduino shield:
+
+![ATCRYPTOAUTH-XPRO-B-Shield](ATCRYPTOAUTH-XPRO-B-Shield.jpg)
+
+Note: ATCRYPTOAUTH-XPRO-B comes with ATECC508A and ATECC608A ICs. Jumper J5
+should be used to enable ATECC508A.