Powering your TinyPilot safely

TinyPilot presents an interesting power challenge on the Raspberry Pi. TinyPilot requires a connection between the target computer and the Raspberry Pi's USB-C port, but the USB-C port is the Pi 4's only power port.

The risk of external power

If you choose to power your Raspberry Pi from an external power source, it's important to take precautions to ensure that you don't damage your Pi or the target machine's USB port.

A computer's USB port also produces power. The risk arises from the fact that USB ports don't guarantee an exact voltage output. The USB power spec allows a voltage range of 4.4V and 5.25V.

Power/Data splitter

TinyPilot is in the process of manufacturing a custom power protector for the Raspberry Pi. It allows the Pi to maintain a data connection with the target computer while also preventing dangerous power backflow.

It is on track to ship by mid-to-late September 2020.

Starting in September, you'll be able to pre-order from the TinyPilot website.

Running exclusively on USB power

It's possible to run TinyPilot exclusively on the power from the target computer's USB port. USB 2.0 outputs 0.5 Amps of power, and USB 3.0 outputs 0.9 Amps. Both of these are far short of the 3 Amps that the Raspberry Pi spec calls for, but the spec is meant to cover all possible usage of the Raspberry Pi, including with multiple USB devices attached. A Pi without peripherals generally uses less than 0.9 Amps of power, even under heavy CPU load.

Still, it's preferable to run the Raspberry Pi with a full 3 Amp power source so that it operates as the manufacturer intended.

The other downside of relying on power from the target computer is that some motherboards stop delivering power to USB ports when the machine is powered down. This would cause the Raspberry Pi device to unexpectedly lose power when it's target machine shuts off.