# First Output

> Original: [Getting Started — First Output](https://tttapa.github.io/Control-Surface/Doxygen/d5/d7d/md_pages_Getting-Started.html)

A minimal sketch that reads a physical control and sends MIDI.

## 1. Include the library

```cpp pico
#include "pico/stdlib.h"
#include <cs_midi.h>

using namespace cs;
```

`cs_midi.h` provides all Control Surface classes. The `cs::` namespace contains everything; `using namespace cs` keeps examples concise.

## 2. Instantiate a MIDI interface

At least one MIDI interface must exist before `Control_Surface.begin()`.

```cpp pico
BluetoothMIDI_Interface midi;
```

Available interfaces:

| Class | Transport | CMake option |
|-------|-----------|-------------|
| `BluetoothMIDI_Interface` | BLE MIDI (BTstack) | `CS_MIDI_BLE` |
| `USBMIDI_Interface` | USB MIDI (TinyUSB) | `CS_MIDI_USB` |
| `HardwareSerialMIDI_Interface` | 5-pin DIN MIDI | `CS_MIDI_SERIAL` |
| `AppleMIDI_Interface` | RTP-MIDI over WiFi | `CS_MIDI_APPLEMIDI` |

## 3. Add MIDI output elements

Output elements read physical inputs and send MIDI messages automatically.

A single potentiometer sending CC:

```cpp pico
CCPotentiometer pot {26, {MIDI_CC::Channel_Volume, Channel_1}};
```

Constructor arguments: GPIO pin, then MIDI address (controller number, channel).

Multiple buttons:

```cpp pico
NoteButton buttons[] {
    {5, {MIDI_Notes::C[4], Channel_1}},
    {6, {MIDI_Notes::D[4], Channel_1}},
    {7, {MIDI_Notes::E[4], Channel_1}},
};
```

## 4. Initialize and run

```cpp pico
int main() {
    stdio_init_all();
    Control_Surface.begin();
    while (true) {
        Control_Surface.loop();
        sleep_ms(1);
    }
}
```

`Control_Surface.begin()` initializes all interfaces and elements. `Control_Surface.loop()` polls inputs and sends MIDI when values change.

## Complete example

```cpp pico
#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"
#include <cs_midi.h>

using namespace cs;

BluetoothMIDI_Interface midi;

CCPotentiometer pot {26, {MIDI_CC::Channel_Volume, Channel_1}};
NoteButton button {5, {MIDI_Notes::C[4], Channel_1}};

int main() {
    stdio_init_all();
    if (cyw43_arch_init()) return 1;
    Control_Surface.begin();
    while (true) {
        Control_Surface.loop();
        sleep_ms(1);
    }
}
```