pub fn set_timer<const TIM: u8>(&mut self, timer: &Timer<TIM, PWM>) {
        let _ = timer;
        // SAFETY:
        // We only write to our OPERATORx_TIMERSEL register
        let block = unsafe { &*PWM::block() };
        block.operator_timersel().modify(|_, w| match OP {
            0 => unsafe { w.operator0_timersel().bits(TIM) },
            1 => unsafe { w.operator1_timersel().bits(TIM) },
            2 => unsafe { w.operator2_timersel().bits(TIM) },
            _ => {
                unreachable!()
            }
        });
    }
Select a [`Timer`] to be the timing reference for this operator

### Note:
By default TIMER0 is used
esp-hal/src/mcpwm/operator.rs