[geeks] home mp3 system suggestions

[Joshua D Boyd]

On Thu, May 30, 2002 at 01:53:00PM -0600, Dave Kimmel wrote:
> On Thu, 30 May 2002, Joshua D Boyd wrote:
> 
> > Yeah, if I'm going to use ethernet, a microcontroller of some sort
> > would be needed.  I was hoping for a completely dumb appliance for
> > simplicity sake.  Also, I'm pretty set against not using an MP3 chip
> > since I don't have much in the way of MP3 files.  If I was using MP3,
> > it would be easy enough to stream over serial.  Instead, I want to
> > send an uncompressed audio stream out.
> 
> That might actually make it easier to do...  I just wonder if a PIC would
> be fast enough to do that.  It would probably have to just set up and
> babysit DMA from the ethernet to memory and memory to the DAC.  I think
> that's how the SliMP3 does things, except for s/DAC/MP3 decoder/ of
> course.

It shouldn't be that hard, even if the microcontroller has to do real
work.  All thats needed is throwing out the excess of the TCP/IP
packet, which might be 3000 or so instructions if a 8bit chip, and
then copying the raw data to the DAC (I'm not sure if it is best to go
directly to the DAC, or to instead find a parallel -> serial chip to
do the job.  The DACs I like the looks of want a steady 1 bit stream
instead of a steady 32bit stream, and I don't know if a serial to
parallel chip is enough.  I'd have to get the full docs for the DAC I
like.  Previous projects have been parallel port driven (then later
serial port driven) machine control, so this would be a step up.

A buffer between the microcontroller and DAC might make life a lot
easier (something along the lines of a simple FIFO buffer), but I
betray my lack of knowledge on circuit design when I say that I don't
know if ready make buffer chips exist, or would I have to make my own
buffer using ram and a controller.

People say that you should work up from the lowel lever stuff to these
projects, but there isn't really anything in between that interests
me.  I do wish I still have my osciliscope.

-- 
Joshua D. Boyd