Sending System Real-Time MIDI messages

[dayunbao]

I'm trying to send the Active Sensing message, but the send_event function is returning False. Here's how I'm doing it:

_CIN_SINGLE_BYTE = const(0xF)
_MIDI_SYSTEM_REAL_TIME = const(0xF0)
_ACTIVE_SENSING = const(0xE)

def system_real_time_active_sensing(self):
        has_sent = self.send_event(_CIN_SINGLE_BYTE, _MIDI_SYSTEM_REAL_TIME | _ACTIVE_SENSING)
        if not has_sent:
            print('Failed to send System Real-Time Active Message')

I've successfully extended the on_midi_event from the MIDIInterface class to receive System Real-Time messages like so:

def on_midi_event(self, cin, midi0, midi1, midi2):
        super().on_midi_event(cin, midi0, midi1, midi2)
        if cin == _CIN_SINGLE_BYTE:
            status_byte = _MIDI_SYSTEM_REAL_TIME | midi0
            if status_byte == _MIDI_SYSTEM_REAL_TIME | _CLOCK:
                self.on_midi_clock()

So I'm wondering what's going on. I saw a comment here https://github.com/micropython/micropython-lib/blob/master/micropython/usb/usb-device-midi/usb/device/midi.py that said:

_CIN_SINGLE_BYTE = const(0xF)  # Not currently supported

Does that mean I won't be able to send System Real-Time messages? Or just that I need to make the call to send_event myself? If so, what am I doing wrong? I'm trying to send that MIDI message within a periodic timer set to 300 ms, since the MIDI 1.0 specs said it should be sent that often. Maybe that's the problem?