On Fri, Sep 22, 2006 at 03:52:01PM +0200, Wouter van Ooijen wrote:
> > It's pretty simple, the ElCheapo is a well known crappy design.
> > Unfortunately it does work some of the time and people really want to
> > believe in a free lunch, so there are a lot of them out there.
> > 
> > For a real PIC programmer, check out my EasyProg
> > (http://www.embedinc.com/products) and Wouter's Wisp628.
> 
> And a few others (various DIY kits, the various WARPs (discontinued?),
> etc). The common factor of these designs is that when they use a serial
> port, they use it to communicate serially, not as a bit-banged source of
> voltages (or they use an USB port). They easy way to detect this is that
> they all contain intelligence (often a PIC). And that PIC must be
> programmed first. If you get a simple progger design (what Olin calls a
> crappy design, I also recall the word Flakeware?) to work, the best
> advice is to use it to program a PIC for one of these more roubuust
> designs.
> 
> Or you can just buy one..

Or you can use a bootloader as your ultimate target if you have a
self programmable PIC.

But in any case you still have a chicken and egg problem. I believe that
parallel ports have a much more stable interface to work from. Serial ports
are all over the place, so you cannot trust any electrical or functional
specification. I've read some reports here about serial ports that swing
between 0 and 1 volt. It's so out of spec as to be laughable.

BTW Wouter knows of what he speaks. He spent several years supporting
an El-Cheapo type serial interface to the WLoader boot loader. IIRC he
found that because serial port specs are all over the place, it's 
difficult to do. And many of the USB to serial converters no longer have
syncronous modem control either. So you cannot trust that you can wiggle
DTR and other modem control signals in a timely fashion.

And down the road it's going to get nothing but tougher. I first saw a
USB only machine with no other expansion ports (slots or otherwise) about
8 years ago. One of my students purchased an Acer Aspire because she thought
it was "cute". An unmitigated disaster at the time. But the time is coming 
where there will be no reason to have any expansion other than USB and PCI
on a PC. At that point for the hobbyist there will be no choice but to
purchase a preliminary programmer, or a preprogrammed USB PIC, even if they 
only want a bootloadable product.

The signs are clear that doing hobby uC work is going to get more problematic
as time moves forward. Between packaging, lower voltage, more complex
interfaces, and specialized development environments, purchasing complete
systems is going to become an attractice option. For example I decided to
take a look at the philips LPC2103. I ended up buying this demo board from
Thailand:

http://tinyurl.com/jyuy4

To do it myself, I'd have to get the chip (which I admit is cheap), then
either design and fab a board, or purchase a carrier like the one that Wouter
sells.  The board that I bought is going to be insufficient for the new USB
PCs that will inevitiably show up. You then need a USB PIC or USB type
LPC2148, which is in a 64LQFP package, runs $11 USD in singles, and isn't
available from Digikey yet.

I mourn the impending loss of the hobby scene. I believe the days of the
tinkerer or numbered.

BAJ
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