# Hardware calibrations

Hardware calibrations serve as a method to get accurate performance from your Pioreactor.

### Stirring calibration (optional)​

info

You'll need the following:

1. Pioreactor HAT
2. Pioreactor sleeve
3. Vial and stirbar

Internally, the Pioreactor will vary the amount of voltage to apply to the stirring motor to reach the desired RPM, however, this can take a few minutes. We can significantly improve this by asking the Pioreactor to create a "map" between voltage and RPM beforehand. Then the Pioreactor only needs to perform a lookup in the map to hit the desired RPM.

note

This is optional, but can really help stirring performance. Creating a stirring calibration is also very easy, so we recommend it.

## Calibrating the stirring on the UI site#

1. Start by filling a Pioreactor vial about 3/4th with water, and place the stirbar inside. Close with lid. Place into the Pioreactor.
2. From the web interface, in Pioreactors, find the Pioreactor you wish to calibrate. Click Calibrate.
3. Click stirring.
4. Click Start. The Pioreactor will increment the voltage applied to the motor, and record the RPM. After it's done, it will collect this data into a calibration curve, and store it locally.

You're done! Your stirring RPM should be much more responsive now.

### Pump calibration​

Calibrating a pump, like a low-volume peristaltic pump, is very important to accurately dispense or remove a target volume. There is no liquid feedback loop in the Pioreactor (unlike in the stirring & RPM relationship), so this calibration curve is important.

There are three pumps on the Pioreactor: media, alt-media, and waste. You don't need to have all three available, and can calibrate them one at a time.

info

You'll need the following:

1. A Pioreactor
2. A pump, with power connection to Pioreactor's PWM outputs
3. An accurate weighing scale
4. Container of water
tip

Supplying external power? Make sure to plug in your external power before pump calibration!

## Calibrating the pumps#

1. We'll perform this routine through your computer's command line. Need help accessing it?
2. Enter ssh pioreactor@<insert unit name>.local.
• For example, to calibrate on our Pioreactor named worker3, we typed ssh pioreactor@worker3.local.
• The default password is raspberry.
3. Enter pio run pump_calibration.
4. Follow the prompts to calibrate your media, waste, and/or alternate media pumps.
5. Calibrations can be performed depending on the frequency of your Pioreactor use.