There are some good ideas here, but you have moved the data movement problem
from SERIAL<->PIC to be PIC<->PIC. You're still going to need some hefty
horsepower to do the PIC<->PIC transfers. Remember, the main processor has
to handle all channels at once. MIDI waits for no man (nor PIC) :-)

Bob Ammerman
RAm Systems
(high function, high performance, low level software)

----- Original Message -----
From: Byron A Jeff <byron@CC.GATECH.EDU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Sunday, May 28, 2000 8:22 PM
Subject: Re: [EE] Microcontroller with 4 USARTs and 40 pins


> On Sun, May 28, 2000 at 06:21:24PM -0300, Edson Brusque wrote:
> > > >If it don't say anything more, it may be the classic 8051's: one
machine
> > > >cycle is formed by twuelve clock cycles, and the instruction cycle
> > > >depends on the particular instruction.
> > > >If You want more speed enhacement look at Dallas MCS-51 compatible,
> > hi-speed
> > > >micros.
> > > Or the AVR, at one xtal clock per instruction (a few take two). 8 mhz,
but
> > > that's 96 to an 8051 apparently.
> >
> >     Ok, but beside the Scenix, there's no 8-bit microcontroller capable
of
> > doing more than 20 MIPS???
> >
> >     And what about the 16-bit micros? Can it be a good option for my
> > project? A US$10-20 microcontroller isn't very expensive to me if it can
do
> > all I need on this project.
>
> A piece of advise. Stick to environments you know instead of striking out.
> Especially when your striking out for more MIPS because you want them for
> something that's easily done in hardware.
>
> I'd advise sticking with PICs. Let me throw out a couple of suggestions.
>
> 1) I'm planning on using a Cirrus Logic CL-CD180 octart. Unfortunately
Cirrus
> Logic has obsoleted the part. In fact they've spun off their communcations
line
> into Basis Communications. I have a couple of samples and an incomplete
> data sheet. If anyone has the pinout I'd really appreciate it. I liked the
> part because of the number of serial ports and the fact that it came in a
> 84 pin PLCC package making it easy to use to hobby work. Basis Comm does
have
> an updated version the CL-CD1865. But it comes in a 100 pin PQFP. Not real
> easy to prototype with.
>
> 2) My second choice was to build an intelligent UART out of a PIC.
Specifically
> for MIDI conversion of the stream into events with timestamps would be
> very useful. Also having buffering so that the main processor can dump
> events ahead of time and have the intelligent MIDI UART deliver them to
the
> channel at the appropriate time. Also doing MIDI channel mapping, splits
and
> volume control in the UART seems interesting. It's also interesting to
consider
> direct transmission of events from one UART to another bypassing the main
> processor.
>
> A single software channel can easily be handled by a 12C509 with a
software
> UART. Of course developing the UART code, the interface to the main
processor,
> (probably something I2Clike) would take some effort. But once it's done
> any number of channels could be added to the system and the main system
> wouldn't have to be uberpowered.
>
>
> Maxim has an interesting discussion in their MAX3100 intro describing the
> issues of software UARTs. You can find it here.
>
> http://dbserv.maxim-ic.com/tarticle/view_article.cfm?article_id=53
>
> The bottom line IMHO is that the traditional approach is better than the
> Winmodem approach because you end up having a highly overpowered processor
> just so that you can have the MIPS to bit bang UARTS. Just remember that
> 8 12C509's will give you 8 MIPS just for the UARTS. Think about the
> distributed processing solution.
>
> BAJ