On Tue, Feb 07, 2006 at 08:54:10AM +0800, Chen Xiao Fan wrote:
> 
> > From: piclist-bounces@mit.edu 
> > [mailto:piclist-bounces@mit.edu] On Behalf Of Byron A Jeff
> > Sent: Monday, February 06, 2006 11:52 PM
> > To: Microcontroller discussion list - Public.
> > Subject: Re: [PIC] [gnupic] noob's 1st ques
> > 
> > Over the years I've had many users successfully utilize the Trivial
> > programmer in its various forms. It served a need for each of my
> > users. I'm simply extending the DIY development model that has
> > already been established. It's certainly not for everyone. However,
> > I feel that it's a niche that still needs to be filled even as we
> > move to PC interfaces that are so complex that no hobby user has
> > any hope of interfacing to it with simple hardware.
> > 

I forgot an adjective: simple commodity hardware

> I can not agree with you on the last sentence. "Simple hardware" is
> very subjective. Yes USB is not as easy as serial port. However,
> USB interface chips have been around for years. Even the USB MCUs
> like the USB PICs are getting more and more popular. I will not
> say they are easy but they are within the reach of hobbyists.

The USB MCU's generally have the chicken/egg problem. Do you know of
any commodity USB MCUs that are bootloadable via USB out the box?

It's not really a foreign concept. The 68HC11 implemented a bootstrap
mode. Here's an app note describing it:

http://e-www.motorola.com/files/microcontrollers/doc/app_note/AN1060.pdf

Fundamentally it was a blank chip with a bootloader installed.

> And actually USB makes the hardware simpler in quite some cases
> because it provides the power. The firmware can be more difficult
> though. The host software can be more difficult. Still it is 
> within the reach of hobbyists.

But it cannot bootstrap itself. So in order to use it you have to
get a minimally used programmer if you develop via bootloaders or
you have to get a preprogrammed chip with at least some minimal
bootloader in order to use it.

I know this isn't a big deal to most of you. But remember that the
original OP of this thread was going to have to multiply this action
with between 20 to 25 students. The bootloader angle was halted
because of the presumption that when the student needed another
project, that they would have to purchase a programmer anyway.

At the end of the day parallel and serial ports are bootstrappable
with easily obtainable, low cost hardware. USB components are not
commodity. Take the Dontronics DLP USB modules page for example:

http://www.dontronics.com/dlp.html

$33 USD + shipping to get a USB interfacable module.

One last point: Bootstrapping with a serial interface means that real
serial ports can also be used. Lots of JDMs have problems with serial ports
with junky (0/5V) outputs. A code dumping board that is designed to work
in that voltage range would also be a boon to those who have real serial
ports too.

BAJ
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