---
title: "DAC"
aliases:
    - firmwareapi/pycom/machine/dac.html
    - firmwareapi/pycom/machine/dac.md
    - chapter/firmwareapi/pycom/machine/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.