[rescue] Parallel ports [was Re: Slightly OT: ?Bad Cap Saga]

Joshua Boyd jdboyd at jdboyd.net
Sun Aug 24 20:38:05 CDT 2008

On Aug 22, 2008, at 12:53 AM, der Mouse wrote:

>> I believe the ATtiny2313 might be exactly what you'd want (hardware
>> UART, external clock not required, DIP package).
> That certainly makes it sound good.  ...google...  Tempting.  It's not
> _exactly_ what I'd want; it demands something very much like a PROM
> pogrammer to get code into it.

Yes.  It is a little bit of a chicken and egg problem.  However, once  
you boot strap a chip (presumably using a cheap parallel port  
programmer), you could use it as part of a device programmer so that  
you don't continue to need a parallel port programmer.

> I also can't help wondering how you can have three general-purpose
> 8-bit I/O registers in a device with fewer than 24 pins; there must be
> something I'm missing, but then, I haven't read the whole doc file.

I think there is something you are missing.  Most likely there are  
three registers, but not all bits work at the same time based on some  
configuration.  At least, that is what I see on a lot of other chips.

>> For a some amount more cash spent on the project, you could build
>> something network capable and a lot faster.  To me, that would be the
>> write way to do it.  It seems to me that ethernet isn't expensive if
>> you can built it yourself, but it is pretty expensive to buy premade
>> modules.
> But then you need a computer on the far side of it, and you're right
> back to getting the bits off a computer.  At least, I can't really
> iamgine how you're going to do any kind of network protocol without
> _some_ kind of computer to implement it.  Or were you thinking of  
> doing
> that in silicon?

No, I was still thinking that the programmer/reader would have a uC,  
just that it talk to your workstation via ethernet instead of serial  
for improved speed.

You can do networking in an FPGA, but that seems nasty.

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