4051 mux problem?

[Fraser, Colin J]

> -----Original Message-----
> From: Stewart Pye [mailto:stew at uq.net.au]
> Sent: 23 July 1999 21:29
> To: Grant Richter; synth-diy at mailhost.bpa.nl
> Subject: Re: 4051 mux problem?
> 
> 
> At 11:31 AM 23/07/99 -0500, Grant Richter wrote:
> >On most micros, a timer can be used to generate
> >an interrupt. This is the interrupt service routine I spoke
> >of. The MIDI input would generate an interrupt of higher
> >priority, so the refresh will hold off until the MIDI
> >routine clears.
> 
> That would be nice if the PIC16F84 had interrupt priority. I 
> thaught the
> next best thing was to poll the timer overflow flag. There is 
> only going to
> be a small variation in timer overflow detection time.  
> <100us for sure. 

On my midi - cv convertor I didn't use a timed interrupt to refresh the
sample and holds.
The main loop processes incoming data if the input buffer is not empty,
otherwise it cycles round all the outputs, refreshing the caps.
The main loop also updates any changing output immediately, as well as
writing the value into ram for the refresh loop.

Unless you need a precise timing interval for LFO generation or suchlike, I
don't see any reason why your S&H refresh rate needs to be so precise.

Colin f