Midi, serial ports, uart's

[Mikko Helin]

Rene Schmitz Wrote:
> 
> Ahh, thats what I've dreamed of, when I made my (very basic) 
> convertor.
> I intend to add more outputs by adding s&h stages which are 
> selected by 
> other lines of the centronics port. So I can make all the 
> programming in C
> on my
> PC)

and Bjarne Nillson Wrote:
> And "where" on the net can we find this multichannel cv/gate 
> converter? 
> Please!


[Colin f's description of 6502 MIDI2CV conv]

Colin f wrote:
>As far as building a parallel port cv output unit goes, if you used a line
>on the parallel port as an address latch load line, you could direct data to
>256 diffferent devices - more than enough to implement the hardware in my
>convertor after the processor. I'm not sure tho' if the load on the port
>wouldn't be too high as you need to refresh the s/h caps at as high a rate
>as possible before the voltage droops. You can't just increase the size of
>the caps as then it takes longer to change the voltage on them, and the
>ability to update many channels at the same time is reduced.

This sounds like a good PIC project: use a pin on B port to receive
an interrupt from parallel port, another to select either address
or data. PIC16F84 has got 64 GP registers, which can be used to
store the data. When the PIC doesn't handle interrupts it does
refresh DAC S/H's, there you need another address/data select line
and write strobe, inverted write strobe writes address to latch,
non-inverted writes to DAC and enables multiplexer's output to
s/h stage. Maybe some delay is needed before DAC -> s/h is enabled.
One or two registers could be used for gate/trigger outputs with
output latches. Actually DAC doesn't need any write strobe, if it's
usual multiplying type converter.

Just some thoughts,
Mikko