[ECOS] AT91SAM7S256 problem with test/example twothreads
Lambrecht Jürgen
J.Lambrecht@TELEVIC.com
Tue Jun 19 20:18:00 GMT 2012
On 06/19/2012 03:16 PM, Jesper K. Pedersen wrote:
> On Sun, 17 Jun 2012 16:43:02 +0200
> "Jesper K. Pedersen"<linux@famped.dk> wrote:
>
>> I am at my wits end getting the twothreads example working on my
>> Olimex P256 board (AT91SAM7S256 based).
>>
>> Calling the cyg_mutex_init does not return. Also I notice that the
>> call to the printf line before the call to cyg_mutex_init prints
>> extremely slow on my terminal.
>>
>> I have set the default console up to tty0 going to ser0. This part
>> works fine with my other software running on the board (normal
>> expected transmission speed).
>>
>> Are there any "gotcha'" involving threading on the AT91 series
>> microcontrollers?
>>
> Problem was solved.
>
> For some reason if you put any output function (printf's) in the
> cyg_user_start the threading will hang.
>
> Removing all output will allow for threading and the example works as
> expected.
>
> I wonder if this is intended or if its a bug in the A91SAM7 eCos.
>
> Best regards
> JesperKP
>
I have lots of diag_printf's in my cyg_user_start() running on an AT91
ARM7 and a ARM9.
Maybe because you use printf?
Be carefull: Code running in initialization context runs with
interrupts disabled and the scheduler locked. Only after cyg_user_start,
the scheduler starts and resumes all threads.
Maybe (if I remember well; search the list for the diff between both
printfs) printf uses interrupts (to know when the hardware has sent a
byte), and diag_printf doesn't.
You must also realize that printf's can take a lot of CPU.
And no, it is certainly not intended or a bug in the ecos CVS code
(although I don't know the twothreads test): it is your bug ;-) .
Success,
Jürgen
--
Jürgen Lambrecht
R&D Associate
Tel: +32 (0)51 303045 Fax: +32 (0)51 310670
http://www.televic-rail.com
Televic Rail NV - Leo Bekaertlaan 1 - 8870 Izegem - Belgium
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