# Drum machine

> A drum machine in Python like FL Studio's channel rack — a step grid you paint, a pad per sound, tempo and swing, with sample-accurate timing from the audio engine.

Source: https://albakore.github.io/pyzed/audio/demos/drum-machine/

(Image: A drum machine playing: the playhead moving over a grid of steps, a pointer painting new tom steps, pads flashing)

A six-sound drum machine: [`examples/audio/drum_machine.py`](https://github.com/albakore/pyzed/blob/main/examples/audio/drum_machine.py).

```bash
python examples/audio/drum_machine.py
```

Click or drag on the [step grid](https://albakore.github.io/pyzed/audio/components/step-sequencer/) to write the beat, play
each sound with its [pad](https://albakore.github.io/pyzed/audio/components/pads-and-buttons/), and change the tempo and
the swing with the knobs.

## Why the timing is exact

The rhythm runs inside the engine, not in Python. A `clock` module ticks every sixteenth note
and drives one `sequencer` per row; each sequencer's trigger strikes its `drum`:

```python
clock = engine.add("clock", bpm=124, division="1/16")
for sound in ("kick", "snare", "clap", "hihat", "hihat", "tom"):
    drum = engine.add("drum", sound=sound)
    seq = engine.add("sequencer", steps=16)
    engine.connect(clock, "clock", seq, "clock")
    engine.connect(seq, "trigger", drum, "trigger")
```

So the beat stays on time however busy the window is. The grid only switches the sequencers'
gates (`engine.set(seq, "gate_5", 1)`), and the playhead reads the step they are on
(`seq.state["step"]`).