* and it needs to use a SPI transfer function, so the best I could do was this, any idea ?

```rs
static mut SPI_INSTANCE: Option<&'static mut dyn SpiDevice<u16, Error=Infallible>> = None;
    extern "C" fn transfer16_function(
        _sensor_id: acc_sensor_id_t,
        buffer: *mut u16,
        buffer_length: usize,
    ) {
        let buffer = unsafe { core::slice::from_raw_parts_mut(buffer, buffer_length) };
    unsafe {
        let spi: &mut dyn SpiDevice<u16, Error = Infallible> = SPI_INSTANCE.as_deref_mut().unwrap();
        spi.write(buffer).unwrap();
    }
}
```