[sdiy] Possible MIDI interface powered by MIDI driving device...

[Tom Wiltshire]

On 24 Mar 2016, at 20:24, Olivier Gillet <ol.gillet at gmail.com> wrote:

>> Steve T's comment about 5V not being a reliable supply suggests to me that for things like this (let's call it "creative rule-bending"?!) we should use uPs that can operate from 5V down to 3V or so. There are such things, so this shouldn't be too difficult to organise.
> 
> The value of the resistors on the OUT side depend on the supply
> voltage. If the MCU is powered by 3.3V, they should be much lower than
> 220 ohm (about 50 ohm) - otherwise you won't be sending enough current
> in the loop!

Ah, yes, of course. Good point, Olivier. I was only thinking of the IN side.

I suppose you could use the uP to detect its own power supply voltage and adjust the outgoing current accordingly, but at that point, it's all starting to get a bit more complicated than it's worth for a thing that removes 0xFE from a MIDI stream.

Tom