On Mon, Apr 14, 2003 at 04:06:49PM +0200, faisal moro wrote:
> hi all
>
> i started looking for a free programmer to build by myself on the
> net, and got lost in 10 minutes: isp,

Sometimes called ICSP: In Circuit Serial Programming.

In short, the target chip to be programmed is inserted into the target circuit.
A cable from the programmer is attached to the target's programming pins.

It eliminates the need to tranfer to the chip to be programmed from the
programmer to the target board and vice versa.

Note that ICSP uses the chip's stock serial programming interface for the job.

> bootloader, could someone
> please explain me these?

bootloader: a program that is loaded into the target chip. The BL then will
accept target programs from an external interface and program them into
the chip. The advantage is threefold:

1) The chip becomes programmable without the need of an external programmer.
2) The BL can choose the interface as opposed to the stock programming
   interface.
3) I have found that the BL interface can often be used as a free debugging
   interface for the application.

> Isp seems a cool feature, but do i have to "sacrify" pins?

Not really. With some care (generally a resistor between the ICSP jack and
the target pin) a programming pin can be reused the vast majority of the time.

> Then, what is a bootloader?

Explained above.

> I need to find a free programmer that works wit IC-Prog (or whatever)
> and that i can build by myself, with the plus of isp.

Almost any programmer can be made into an ICSP one with the use of a cable.

BTW no programmer is free. All take some parts and some effort to put together.

Check out my Trivial Programmers: http://www.finitesite.com/d3jsys
They are designed for dumping bootloaders into 16F87X parts. but work fine
as standard or ICSP programmers. Cheap, quick, and easy to build.

Not sure if it works with IC-Prog though.

BAJ

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