[ECOS] Re: eCos invalidating JTAG on ARM architecture ?

Alexandre thekyz@gmail.com
Thu Jul 5 14:33:00 GMT 2007

A little update on that, the problem does not occur if i use
cyg_usr_start instead of main as an entry point.

On 7/5/07, Alexandre <thekyz@gmail.com> wrote:
> Hi everyone,
> I finally manage to run eCos on my eval board (yipee!) thanks to all
> of you guys but i have a slight debugging problem (again i know, I'm a
> problem maker -.-).
> After I upload my eCos code to my board via JTAG (code which is fully
> functioning by the way), I can't by any mean reach it again via JTAG.
> OpenOCD just says it can't communicate with my board. Seems like eCos
> just disable my JTAG. The only way I can access my micro controller
> again is by UART, erasing the flash using ISP, and then reflashing it
> by JTAG works anew. So it works, but I can't debug the thing.
> I lurked through the mailing list to see if anything like that
> happened to someone and couldn't find anything so my first guess is I
> did something wrong (I'm a pessimistic person).
> There are two JTAGs available on my micro controller, one is supposed
> to be always enabled when a definite input is pulled to LOW by
> hardware means (which I've done, this is the way I manage to upload
> the eCos code in the first ways). The second JTAG is enabled by
> registry means.
> I tried to upload a dummy code without ecos and the first JTAG (the
> hardware enabled) works perfectly without any init. The second one
> (the software enabled) works also if I input the correct init (which I
> did, I mean I managed to make it work ^^).
> But with eCos, neither works :(
> I tried to put my init code from the dummy software in the eCos init
> but I can't make the second JTAG work and the first one isn't working
> either.
> I was guessing maybe eCos init for ARM (or maybe the olimex lpc2106
> port) may have a thing which disable JTAG. Is it possible or did I do
> something wrong and JTAG should work with eCos ?
> For reference I use an LPC2106 ARM7 micro controller.

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