# FAQ

> Original: [Frequently Asked Questions](https://tttapa.github.io/Control-Surface/Doxygen/da/dc1/FAQ.html)

## Can cs-midi be used as a general MIDI library?

Yes. You can use the MIDI interface objects directly for sending and receiving, without using the element system or `Control_Surface` singleton.

Sending:

```cpp pico
BluetoothMIDI_Interface midi;

int main() {
    stdio_init_all();
    if (cyw43_arch_init()) return 1;
    midi.begin();
    midi.sendNoteOn({MIDI_Notes::C[4], Channel_1}, 127);
    midi.sendNoteOff({MIDI_Notes::C[4], Channel_1}, 127);
    while (true) { midi.update(); sleep_ms(1); }
}
```

Receiving with callbacks:

```cpp pico
struct MyCallbacks : MIDI_Callbacks {
    void onChannelMessage(MIDI_Interface &, ChannelMessage msg) override {
        // handle msg
        (void)msg;
    }
} cb;

// in main(): midi.setCallbacks(cb);
```

## Can addresses or channels be changed at runtime?

Yes, through banks. A `Bank<N>` groups bankable elements and a selector controls which bank is active. See the [Banks](../../examples/04-banks/) examples.

## What's the difference from Control Surface?

cs-midi is a source-level extraction of Control Surface for pico-sdk. Key differences:

- `#include <cs_midi.h>` instead of `#include <Control_Surface.h>`
- Standard `main()` replaces Arduino `setup()`/`loop()`
- `cs::` namespace instead of top-level
- BTstack BLE backend instead of ArduinoBLE/Bluedroid
- No MCU protocol, displays, FastLED, or hardware expanders (yet)

## What radio modules are supported?

The BLE transport uses BTstack with the CYW43 radio. Only the **Infineon RM2** module has been tested. Other CYW43 variants may work but are unverified.