Video on YouTube — shot 2026-09-22 by andeye (Laura Currie, edit; Martin Currie and Bingqiao Zhao on camera). Loads from YouTube only when you press play.

Raspberry Pi and HAT

Follow Pioreactor’s 40 ml v1.5 hardware setup guide, with these changes. This step stops at the bare HATThe Pioreactor circuit board that plugs onto the Raspberry Pi's pin header. It carries the PWM and LED outputs and the 12V barrel jack.: the vial holder assembly, in the next step, covers the shunt connectorA small jumper on the HAT. In the position closest to the LED outputs it feeds the 12V supply to PWM channels 1 to 4..

1. Assemble the Raspberry Pi and the HAT on a Raspberry Pi 5 1GB. Use the kit’s 8 mm screws where the guide says 10 mm, with a hex nut on all four.

2. Move the HAT’s shunt connector to the position closest to the LED outputs, now, while the HAT is bare (external power).

   Miss this and you take the unit apart again

   No error shows. PWM channelsOne of the HAT's five switched power outputs. In this build: 1 stirring, 2 media pump, 3 waste (product) pump, 4 CO₂ solenoid (relay), 5 heating. 1 to 4 ignore the 12V supply, so the peristaltic pumpsA pump that squeezes liquid along flexible tubing with rollers, so the liquid never touches the pump. and the PWM 4 CO₂ solenoidAn electric valve on PWM channel 4 that opens to sparge. It must be 3-way venting (3/2), so the line vents when it closes. run on the Pi’s own supply. The solenoid will not drive, and spargingBubbling gas through the culture. Here, CO₂ from the cylinder flows down the anode on a timer set in the electroPioreactor job. looks like a gas train fault. Moving the shunt later also invalidates any stirring and pump calibration.

Parts

• 1×Pioreactor 40 ml v1.5part
• 1×Raspberry Pi 5part
• 1×27 W USB-C power supplypart

Tools

• 1×Phillips PH0 screwdrivertool

Check your work

1. Where is the HATThe Pioreactor circuit board that plugs onto the Raspberry Pi's pin header. It carries the PWM and LED outputs and the 12V barrel jack.'s shunt connectorA small jumper on the HAT. In the position closest to the LED outputs it feeds the 12V supply to PWM channels 1 to 4. now?

   • On the two pins closest to the LED outputs
   • On the two pins closest to the barrel jack
   • Off the HAT, not on any of its pins
   Show the answer

   Answer: On the two pins closest to the LED outputs

   • If you see On the two pins closest to the barrel jack: Move it to the pair closest to the LED outputs, now, while the HAT is bare.
   • If you see Off the HAT, not on any of its pins: Find it and fit it on the two pins closest to the LED outputs, now, while the HAT is bare.

≈ 0.03 g CO₂e per view