MIDI receiving continously in serial monitor - "Message, type=248, data = 0 0"


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MIDI receiving continously in serial monitor - "Message, type=248, data = 0 0"

I built the MIDI circuit for 5-pin DIN here: https://www.pjrc.com/teensy/td_libs_MIDI.html
This circuit worked well for me the last time I built it, but this time I am getting this message continuously: "Message, type=248, data = 0 0" It looks like a timing related message? The notes do come through correctly such as "Note On: ch=1, note=40, velocity=79" and I can use the notes to do things like trigger LEDs, but I don't think I am supposed to be receiving any MIDI Message continuously. Typically RX should be continuously high and only when RX is pulled low is a message started, correct? The code is just the "Example Input Program" according to the same link/page above.

I know I need a scope - it's the first thing I plan to buy when I can afford one.

midi serial stream.PNG
Whatever is generating the notes is presumably sending the timing message. This may be an optional setting in the MIDI device you're using and can be switched off.

Its MIDI packet type 0xF0, the MIDI clock, sent 24 times per quarter-note. Used for synchronization, presumably your MIDI source has this enabled. This is typically used if the source is something with a settable tempo - a bare MIDI instrument wouldn't normally be sending this but a drum machine or sequencer probably would by default?
Thank you all for your input. I feel foolish for not cross-checking with a keyboard. You are 100% right I was testing with a drum machine (Yamaha RY9) and I have found the sync clock settings in the manual. I'll look into active sensing next. Thanks again!