Initial doc for the orangecrab fpga

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+# Orangecrab 0.2 Testing
+
+This page is for documenting the orangecrab bring-up, from blinky to microwatt.
+
+## Further links
+
+* HDL Workflow [[/HDL_workflow]]
+* ECP5 Versa [[/HDL_workflow/ECP5_FPGA]]
+* Microwatt [[/HDL_workflow/microwatt]]
+
+## Requirements
+
+Instructions assumed to be called in a schroot environment.
+
+1. Call nextpcr-ecp5-install
+1. Add environment vars for libtrellis and nextpnr-ecp5 (otherwise building with nmigen-boards will fail).
+    export PATH=/usr/local/libtrellis/bin:/usr/local/nextpnr-ecp5/bin:/usr/lib/ccache:"$PATH"
+1. apt install dfu-util
+1. Add a udev rule for the orangecrab in /etc/udev/rules.d/ . The rule was taken from <https://github.com/orangecrab-fpga/orangecrab-hardware/blob/main/contrib/10-orangecrab.rules>.
+    ATTRS{idVendor}=="1209", ATTRS{idProduct}=="5af0", MODE="0666", GROUP="plugdev", TAG+="uaccess"
+1. Git clone "nmigen-boards" from gitlab <https://gitlab.com/nmigen/nmigen-boards>
+1. cd into "nmigen-boards" and install by calling:
+    python3 setup.py develop
+
+## Setting orangecrab into DFU
+
+1. Press and hold the button on the orangecrab.
+1. Plug in the usb cable.
+1. Calling the following should show two devices: one is the RISCV firmware bootloader, the other is the user bitstream.
+
+## Build and upload "blinky"
+1. cd into "nmigen-boards/nmigen-boards".
+1. Build and program the board: 
+    python3 -m nmigen_boards.orangecrab_r0_2
+1. You should now have a *very* bright LED flashing!