# 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.

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.

1. Click stirring

1. 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​

##### info

You'll need the following:

1. Pioreactor HAT
2. A pump per liquid input/output, with power connection to Pioreactor's PWM outputs
3. An accurate scale, or accurate graduated cylinder
4. Container of water

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.

##### note

There currently is no web interface for this calibration, and must be done on the command line. Maybe in a future release!

From the command line, run pio run pump_calibration. You'll be shown a command-line application that will guide your through the pump calibration.