Hi,

I didn't want to be too verbose in my original post. Thanks
to everyone who has replied so far.

On Thu, Apr 08, 2004 at 12:35:38AM -0600, Robert Rolf wrote:
> You are not clear as to whether the PC is a slave or a master.
> If the former, just get a PCI DMX card and be done with with.
> http://www.pro-music-news.com/html/studio/e20323so.htm

Well, this is for a system where every dollar counts. Right now
time is plentiful, and money is not. Also, there is no room for
an add on card inside the enclosure, making a PCI card far too
large.

> Or a cheap serial card and change the crystal so that
> 115.2kbps becomes 250khz. 1.8432Mhz -> 4Mhz.
> If you are lucky the embedded PC has a dedicated clock crystal
> for the multifunction I/O chip, and you could change that.
> A lot of MF chips start with 12 or 24mhz and can be programmed
> to run with a higher starting baud rate divisor. (e.g. no
> divide by 13 before the rate select mux.)

I was wondering about maybe doing it just with the computer. I
read the datasheet for the National 16550, and it seems that with
some DMA action, it would be pretty efficient to send with the PC
directly. I've had pretty good luck with my super-io chip on the
motherboard in terms of low CPU overhead, at 115.2kbps anyway.


Andrew

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