and then something like:

```rust
fn write_notepad<W: embedded_io::Write>(&mut self, uart: &mut W, contents: &[u8]) {
    // send the write notepad command
    uart.write(&[0x12, 0x34]);
    // send the length
    uart.write(&u16::try_from(contents.len()).unwrap().to_be_bytes());
    // send the contents
    uart.write(contents);
    // flush to make sure all have been sent
    uart.flush();
}
```