Schematic of a GM ALDL -> PC converter

[Mark Bjork]

John Faubion wrote:
> 
> >  You can't program a PC UART to 8192 baud, but
> >you can program it to 8228 using a divisor of 14, which is close enough.
> 
> Actually why not change the XTAL to a 3.2768Mhz and use a divisor of 25?
> With the UART's internal divisor of 16 and a programmable divisor of 25
> would get 8192. Plus this is a standard crystal which costs about a dollar.
> Dual port serial cards for the PC are around seven dollars now. Looks like
> a cheap way to talk to it. Or I guess someone with a bit more EE skills
> could probably whip up a circuit for it using that crystal, a UART, a
> couple IC's and a few discretes to connect to a parallel port. Anyone with
> the know how for this willing to take a shot. I'm willing to build it.
> 
> John Faubion
> jfaubion at beaches.netThe only hardware you need is a ciruit to "invert" the data. Other than 
that you can ( as someone mentioned earlier in this thread) do the rest 
in software. We (a friend and I) did connect a pc to the ALDL port over 
the weekend, and did obtain data from the port, but, we hadn't "borrowed" 
any hardware from work to do the inverting. Tonight, we hope to have a 
simple serial communication inverter circuit ready. Then we should be 
able to get valid data. The data we obtianed would be correct if we did a 
BSL on each word (I think that would work) but since the "level" of the 
start bit was inverted, the data is tough to decipher. I will post the 
results of our "test" as soon as we have something further.

Mark