# Synchronize mixers

:::{tip}
Starting from version 2.12.0, the Presto API has an *autoconfiguration* feature to select the
optimal DAC configuration automatically based on your choice of frequencies. When using this
feature, calls to {meth}`~.Hardware.configure_mixer` are handled differently and do not require any
special care to be synchronized across different ports.

If do not use the autoconfiguration feature and still want to specify the DAC settings manually,
keep reading. Otherwise, head over [here](./direct_mixed.md#synchronize-multiple-mixers) to see how
to update your old code.
:::

When setting up digital mixers with {meth}`.Hardware.configure_mixer` the parameter `sync`
indicates when to start the mixers. When we pass `sync=False` the mixer is 'armed' and the
numerically-controlled oscillator (NCO) connected to the LO port of the mixer is ready to be
started. When we pass `sync=True` that mixer's NCO is 'armed' and all the already armed NCOs are
started at the same time. The default value of the `sync` parameter is `True`.


In the following example, the NCO that is at 5 GHz starts first. After that, mixers with NCO
frequencies 6 and 7 GHz start together. 

```python
pls.hardware.configure_mixer(freq=5e9, in_ports=1, out_ports=1)

pls.hardware.configure_mixer(freq=6e9, in_ports=2, out_ports=2, sync=False)
pls.hardware.configure_mixer(freq=7e9, out_ports=3, sync=True)
```