Add instructions on how to assemble a device

README.md

@@ -25,6 +25,62 @@ Arduino IDE built-in library manager, as it has multiple bugs, and many
 operations are implemented in an ineffective way. My pull requests to address
 those have not been reviewed at the time of writing.
 
+## Assembling
+
+Recommended parts list:
+
+* [Adafruit ItsyBitsy nRF52840 Express](https://www.adafruit.com/product/4481)
+* [MCP2515 boards](https://www.amazon.com/gp/product/B07J9KZ4L4/) (2+ pcs recommended so you can test without a car)
+* [16 MHz quarz oscillators](https://www.amazon.com/gp/product/B00NQ82OM0/) (in case your MCPs have 8 MHz quartzes)
+* [Jumper](https://www.sparkfun.com/products/9044) (in case your MCP comes without it, like mine)
+* [Mini Breadboard](https://www.sparkfun.com/products/12047)
+* [Jumper wires](https://www.sparkfun.com/products/124)
+* [JST SM connectors](https://www.amazon.com/gp/product/B07QG2TN1X/)
+* Crimping tool for JST connectors
+* ~22 AWG wires
+
+First, solder the male headers to your microcontroller board.
+You'll need G, USB, SCK, MO, MI and 7.
+It's also recommended to solder 9, R and 3V for future improvements and
+mechanical stability on the breadboard.
+Soldering male headers is a lot easier if you first insert them into a
+breadboard.
+
+Put the jumpers on the breadboard this way to allow for neat hidden
+connections:
+
+![Breadboard with jumpers](images/board_with_jumpers.jpg)
+
+Then, put the microcontroller board on the breadboard:
+
+![Adafruit ItsyBitsy nRF52840 Express on the breadboard](images/nRF_on_board.jpg)
+
+Un-solder the header from the MCP board and solder a new header on the other
+side of the board to make it more breadboard-friendly.
+
+Replace the 8 MHz quartzes on your MCPs with 16 MHz quartzes, if needed.
+Install the jumper that connects the 120 Ohm terminal resistor.
+Optionally, un-solder the screw terminal and solder a twisted pair of wires to
+the board, and finish with a nice JST SM connector:
+
+![MCP2515 board with mods](images/mcp_mods_closeup.jpg)
+
+Finally, put the MCP on the breadboard.
+
+Check connections:
+
+MCP pin | Microcontroller pin
+------- | ------------------
+VCC | USB
+GND | G
+CS | 7
+SO | MI
+SI | MO
+SCK | SCK
+INT | Currently unused, may use 9 in the future
+
+Optionally, put everything into a nice enclosure.
+
 ## Testing
 
 You don't need to always be in the car to test changes to this library. Instead,