On 1/3/07, Charles Manning <[EMAIL PROTECTED]> wrote:
> If you've been around ARM-based micros before, then getting going on the
> low-levels is not too difficult. The hardest part was getting the i2c link to
> the AVR going properly because the documentation did not match what was
> happening, compunded by the fact that the SAM7 I2C peripheral is buggy.

I see. I've had minimal (cousework, using windows dev tools)
experience with arm architectures, but my objective now is to get a
full toolchain for open platforms.

> As Lawrie has already stated, we can run code in three ways, one of which
> supports gdb-level debugging through jtag.

Speaking of that, what jtag probe do you use for debugging, and does
it work in linux? I'm looking to buy one (because loading code and
watching the nxt do "nothing" is getting old very quickly), but I'd
rather not have to fight with jtag-gdb for a few weeks before I can
start debugging.

> That's the model being used here.
> Just replace main with the code you want and you're off to the races.
>
> Since I've used dead code stripping, you can even leave the VM code in the
> build (but don't call it :-)) and it will just get stripped from the final
> image.

I saw that. The code you have looks very nice. I had started doing
things slightly differently: I have an asm/C bootstrapper that takes
care of stack setup, as well as flash, clock and AIC initialization,
before copying a payload into ram, remapping and starting execution.
The bootstrapper is designed to be as generic as possible, so that you
can bootstrap into anything and start at kernel_main() with interrupts
disabled and the basics configured.

I think I'm still going to go on with my own kernel code (if only to
learn about writing the stuff and working the toolchain), but I will
certainly take inspiration from the lejos kernel, and try to stay
compatible with it where possible.

Have you considered moving the platform code into a project separate
from the lejos VM?

> We got a substantial distance down the road before the Lego fw was available.
> Thus far I've only used it to confirm a few things I've seen on a scope etc.

Right. I looked mostly at the AVR code, to see how the copyright
string was being handled on the receiving end.

- Dave

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