Hi Dan ( @dankril ),
can you please confirm that your solution is still working 100% reliably?
I’m seeing similar issues. I tried buffering with a 7405 (Open Collector TTL inverter) and later with an optocopler. I also used (tantalium) decoupling capacitors and verified signals with a multimeter and oscilloscope. I see clean (relatively slow) rising edges with no overshoot.
It seems to work for a few minutes, but then the RPI does not seem to detect the input signal any more (nor the rising, nor the descending edges)
I’d appreciate if you could elaborate a bit on your working solution
More info here: Raspberry PI GPIO input buffer circuit
Thanks so much,
chrisV