SynthModules

Been a little quiet here lately.  I just finished a self-powered
MIDI processor http://modularsynthesis.com/processor/processor.htm.

I was testing it on a number of MIDI devices and to my surprise it
wouldn't work on the PSIM MIDI output.  In looking at the signals
on an oscilloscope, the TxD V(ol) was only going down to 1.5 volts.
This pin is spec'd for a full 5 volt swing.  There is only a 220 ohm
resistor in series with it.  There is still enough voltage swing that
it functioned correctly with MIDI.

Here's another one for the FAQ.  When using the enablehserial and
sethserial commands to drive the TxD line you cannot use any other
commands that use this pin.  At the beginning of my code I had a
'high p15' command to initialize the TxD line high.

With this command the voltage swing on TxD is 1.5 to 5 volts.
Without this command the voltage swing is a full 0 to 5 volts.
I have no idea what it is doing.

Go figure. - Dave