The smell of solder in the evening ...

Wiring Diagram from the underside of the prototype board

Most of the prototype board materials arrived today. Including the JST 2.0 mm headers. These are close enough to the grove shield headers so I do not expect a problem with them.

After examining the circuit diagrams and digging into the relay logic and connector header pin outs I formed a wiring diagram plan.

Essentially the connectors are laid out in a manner where the DC supply connects into S4 header with a cable. This provides +12V and GND, which must be routed to switching relays. via S1 and S7. So now S1 and S7 are switched +12V and GND. These will now the the "socket" that needs to control the Fan's and the LED's. Both of which take 12V. The Fans and LED's connect to S2 and S8. So... the switch socket needs to be wired to the receptacle that connects to the Fan's and LEDs. This is why you see the blue and yellow lines jumping over from the left column to the middle column. Note, GND is extended to the middle column from the DC supply source on S4.

S5 is intended to connect to the CO2 sensor. So it gets its own isolated signals. It prefers 3.3v and arduino logic ground. In addition it has Rx and Tx pins. These need to be wired in a manner that the Ardunio Rx(pin 12) connects to the CO2 Sensor (Tx pin 7 on the sensor, the yellow wire).

Lastly we need to wire up the 5V logic controls on S3 and S9 that route to the relays which are controlling the Fans and LED's.

After it was all done, this is what I have:

Here is the color legend:

• White = 12V from S4 DC supply
• Green = GND from S4 DC supply
• Blue = 12V relay out
• Gold = other 12V relay out
• Black = Arduino GND
• Red = Used for 5V arduino, and 3.3v arduino (as I lacked another color).
• Little blue wires = Those are the digital logic pins which I wire wrapped to the prototype board.

I ohm'd out the connections and tested from the top of the board to ensure the pins that should be linked together were indeed connected.... So far so good. Only risk here is the Grove shield arrives and the sensors on order from China dont match the JST 2.0 mm connector.... we will wait and see if my gamble paid off.

Prototype board assembled and connected to Arduino and Pi.

 Once the sensors and grove shield arrive, which should be in the next 2-3 weeks (must be shipped over on a container boat at this rate), final system debug can begin. I plan to walk Elon through all of this, but if he had to wait while I solder this together I would have never gotten it done. He is very excited to grow food in this, and that is why I am spending the time at night to jump this project forward quickly.