The whole Mushrooms' Paradise blog
Power supply
The power supply is an ATX PSU with 24-pin cable. The power connector pinout
Detailed description can be found here: ATX Power Supply Pinout and Connectors. Basically all back wires are Ground, yellow - 12V, Orange - 3.3V, Red - 5V. Note: green wire - PS_ON needs to be connected to the Ground for the power supply to work.
Raspberry PI
First, I glued on 4 small heat sinks because my PI will be always on. I got regular PI heat sinks from Amazon.
RPI pinout with a short guide to all type of pins of can be found here: Raspberry Pi GPIO Pinout: What Each Pin Does on Pi 4, Earlier Models
I used 3.3V supply for relays from Raspberry PI itself so the signal and 3.3V are connected to the ground in the same circuit.
Enviro HAT
I didn’t snap it onto the Pi as intended but connected all 12 pins using jumper wires. Description on how to connect them can be found here: Aquaponics Box: #2 - Hacking the HATs (both HAT... | element14 | 1 Meter of Pi. The image below is from the same blog entry, from 1 m3 of PI Design Challenge. Green pins and pins marked with red dots are not used by Enviro.
In addition to these pins 5V (pin 2) and ground (pin 6) are connected to Enviro. Enviro HAT doesn't need 3.3v connection because it has built-in 5v to 3.3v converter.
So the list of the pins connecting Raspberry PI to Enviro HAT: 2, 6, 12, 26, 32, 38, 3, 5, 19, 21, 23, 35
Enviro HAT was actually disappointing. When it was snapped on RPI both temperature and humidity reading were off. Temperature was a couple degrees higher and humidity was 90% instead of 30%. But even if the data was right I still need to connect Enviro by jumpers, because I need access to several other pins.
Humidifier components.
The USB Humidifier is connected to IOT Relay “Normally Off” outlet. IOT Relay is controlled by GPIO pin 16 and Ground. The IOT relay is used so I don’t have to cut humidifier wires. I feel uncomfortable tinkering with 110V wires. The description of the IOT relay can be found here: IoT Relay.
There is nothing special to say about the humidifier itself - It was the cheapest USB model I found on Amazon. The humidifier doesn’t have a switch, but a push button. So as soon as current stops it will turn off and will not turn on until the button is pushed even if there is current. To avoid this problem I used 2 rubber bands and 1 small screw to keep the button always pushed in. If I will need to get another one in the future, I will make sure it has an ON/OFF switch.
Fan components.
I have 3 12V 120mm computer case fans. All are powered by one relay, and are connected in parallel. The 3.3V relay is using 3.3V, ground and GPIO pin 27 (as a signal) from RPI. 12V supply for the COM port is connected to the PSU. Ground from the PSU is connected to all fans.
LED strips.
I have 3 5V 5m LED strips. All are powered by one relay, connected in parallel. 3.3V relay is using 3.3V, ground and GPIO pin 22 (as a signal) from RPI. 5V supply for the COM port is connected to the PSU. Ground from the PSU is connected directly to all fans.
To be continued