last note diondokter, I honestly find this works well, for `0..=32` connected peers over a shared RS-485 bus:

```rust
pub struct Controller<R: RawMutex + 'static> {
    peers: Mutex<R, [Peer; NUM_PEERS]>,
}

impl<R: RawMutex + 'static> Controller<R> {
    pub const fn uninit() -> Self { /* ... */ }
    pub async fn init(&self, sli: &mut RawFrameSlice) { /* ... */ }
    pub async fn send(&self, mac: u64, frame: FrameBox) -> Result<(), SendError> { /* ... */ }
    pub async fn recv_from(&self, mac: u64) -> Result<FrameBox, RecvError> { /* ... */ }
    pub async fn step<T: FrameSerial, Rand: RngCore>(&self, serial: &mut T, rand: &mut Rand) { /* ... */ }
    pub async fn connected(&self) -> heapless::Vec<u64, NUM_PEERS> { /* ... */ }
}
```