Thanks.adafruit_support_bill wrote:There is a post on the VDSP forum by one of the VLSI staff about MIDI misbehaviour on the VS1053 due to FIFO overruns:
However that thread turned out that the poster didn't have the RX input pulled up. Where as in my schematic I show this being pulled up to 3V3 through a 470R resistor.
If this were not pulled up, as it is coming from an opto isolator, it would not work at all.
So I don't think that is the solution here.