# DAC

The DAC is used to output analog values \(a specific voltage\) on pin `P22` or pin `P21`. The voltage will be between `0` and `3.3V`.

## Quick Usage Example

```python
import machine

dac = machine.DAC('P22')        # create a DAC object
dac.write(0.5)                  # set output to 50%

dac_tone = machine.DAC('P21')   # create a DAC object
dac_tone.tone(1000, 0)          # set tone output to 1kHz
```

## Constructors

#### class class machine.DAC\(pin\)

Create a DAC object, that will let you associate a channel with a `pin`. `pin` can be a string argument.

## Methods

#### dac.init\(\)

Enable the DAC block. This method is automatically called on object creation.

#### dac.deinit\(\)

Disable the DAC block.

#### dac.write\(value\)

Set the DC level for a DAC pin. `value` is a float argument, with values between 0 and 1.

#### dac.tone\(frequency, amplitude\)

Sets up tone signal to the specified `frequency` at `amplitude` scale. `frequency` can be from `125Hz` to `20kHz` in steps of `122Hz`. `amplitude` is an integer specifying the tone amplitude to write the DAC pin. Amplitude value represents:

* `0` is 0dBV \(~ 3Vpp at 600 Ohm load\)
* `1` is -6dBV \(~1.5 Vpp\), `2` is -12dBV \(~0.8 Vpp\)
* `3` is -18dBV \(~0.4 Vpp\).

  The generated signal is a sine wave with an DC offset of VDD/2.