# Control lanes

> Control cables carry block-rate values, normally 0 to 1, that plug into any parameter through its socket.

Source: https://docs.tune.toys/concepts/control-lanes/

A control cable carries lanes: numbers, normally between 0 and 1, that change from one audio block to the next. They are the cheap, slow wire of a Toy, used for modulation, sensors and anything that does not need an audio sample rate.

## What it does

A Toy cable is one of four types: audio (channels), control (lanes), MIDI (one stream carrying all 16 MIDI channels) or any (an unresolved [bus](https://docs.tune.toys/concepts/buses/) end). Control nodes (`ctl.*`) run once per audio block inside the shared engine, so a control value moves in block-sized steps. Use [Smooth](https://docs.tune.toys/nodes/ctl.smooth/) when a stepped value would click.

A one-lane control cable can plug into any node parameter through its parameter socket. In the connection the destination port is `@` plus the parameter id, for example `{ "node": "svf", "port": "@cutoff" }`. The lane value from 0 to 1 maps across the parameter's range, logarithmically for log parameters such as cutoff, and the knob then shows the cable as its owner. A parameter with a cable cannot also have an LFO or a MIDI mapping. A parameter socket needs a one-lane source; use [Select lanes](https://docs.tune.toys/nodes/ctl.select/) to pick one lane out of a wider bundle.

Some nodes also send events: a labelled outlet beside the main output, such as `done` on [Envelope](https://docs.tune.toys/nodes/std.envelope/), `wrap` on [Counter](https://docs.tune.toys/nodes/ctl.counter/) and `cycle` on [Control LFO](https://docs.tune.toys/nodes/ctl.lfo/), that is 1 for one block when the event happens and 0 otherwise, like [Compare](https://docs.tune.toys/nodes/std.compare/) in Trigger mode. It is an ordinary one-lane control output, so cable it into a trigger input or a parameter socket; because control runs once per block, an event never lasts less than a block and two events inside one block count as one.

## Tips

- Shape a lane with [Scale](https://docs.tune.toys/nodes/ctl.scale/) for depth, offset and curve before it reaches a socket.
- [Envelope follower](https://docs.tune.toys/nodes/ctl.follow/) turns audio level into lanes; [MIDI to control](https://docs.tune.toys/nodes/midi.to-control/) turns notes into six lanes.
- Choice parameters (such as filter type) are discrete and are not good cable targets.

## See also

[Control LFO](https://docs.tune.toys/nodes/ctl.lfo/), [Constant](https://docs.tune.toys/nodes/ctl.const/), [Select lanes](https://docs.tune.toys/nodes/ctl.select/), [Cables and channels](https://docs.tune.toys/concepts/cables/).