[U-Boot] embedded standalone app for AVR32

[FLYNN Sean]

Hello all,

I have been struggling for weeks trying to get a u-boot application with
interrupts running on an AVR32 STK1000 board.

 

I have been able to get the application to run properly when loaded
directly to 0x00000000 flash memory complete with serial interfaces and
interrupts.

I have also been able to get a small application (without serial and
interrupts) to be successfully run and exit (correctly returning control
to u-boot).

 

I just can't get these two pieces to run together.  I have been in
contact with Atmel and they provided me a linker script (included in zip
file) which got my app to run at a different location in memory.

 

I'm a bit of a newbie to embedded programming so I apologize if I ask
any dumb questions.

 

To simplify my issues I created this extremely stripped down version of
my app to isolate my issues.

Blink.c

 

#include <avr32/io.h>

#include <sys/interrupts.h>

 

volatile struct avr32_pio_t *piob=&AVR32_PIOB;

unsigned int PIN_MASK = 0x00000003;

volatile struct avr32_rtc_t *rtc=&AVR32_RTC;   

volatile unsigned int number_of_blinks = 0;

 

__int_handler *rtc_cb();

 

int main (int argc, char *argv[])

{

    

    piob->per  = PIN_MASK; 

    piob->oer  = PIN_MASK; 

    piob->idr  = PIN_MASK; 

    piob->pudr = PIN_MASK; 

    piob->codr = PIN_MASK; /* set LED's to low */

        

    number_of_blinks = 0;

    unsigned int clock_msec_precision = 500;

    struct avr32_rtc_ctrl_t rtc_control_register;

    rtc_control_register.topen = 1;

    rtc_control_register.pclr = 0;

    rtc_control_register.en = 1;

    rtc_control_register.psel = 0;

    rtc->CTRL=rtc_control_register;

    

    rtc->val = 0x00000000;//initial val=0

    rtc->top = 16 * clock_msec_precision;

    rtc->ier |= AVR32_RTC_IER_TOPI_MASK;//interrupt enabled  

    

    set_interrupts_base( (void *) AVR32_INTC_ADDRESS );

    register_interrupt( (__int_handler) (rtc_cb), AVR32_RTC_RTC_IRQ/32,
AVR32_RTC_RTC_IRQ%32, INT0);

    init_interrupts();

    

    while ( number_of_blinks < 40);

 

       return (0);

}

 

__int_handler *rtc_cb()

{

    // clear the interrupt

    rtc->icr |= AVR32_RTC_ICR_TOPI_MASK;

    number_of_blinks++;

    // toggle the led

    if ( piob->pdsr&PIN_MASK)

         piob->codr=PIN_MASK;

    else piob->sodr=PIN_MASK;

    

    return (void *) 0;

}

 

Building this app with "avr32-gcc blink.c -o blink" and loading it to
0x00000000 runs fine.

 

I attached a small project which I received from atmel which provided
assembly for a _start routine, a linker script and a make file.

 

With some modifications to the Makefile I was able to run code, similar
to above that blinked an LED but did NOT USE interrupts.  This code was
able to be loaded and run from various points of flash and SDRAM.

 

When I included the interrupts in this application I was receiving
__heap_start__ and __heap_end__ undefined (along with a few other minor
linking errors that I fixed due to gcc libraries that were not linked
in).  I attempted to define these areas in the linkerscript and was able
to get my app to build but it would not run.  I attempted many different
iterations defining the heap sections unsuccessfully.   FWIW I also
attempted to allocate some memory using malloc to see if the heap was
the problem and that wouldn't run either.

 

Hopefully I made myself clear in this e-mail but my ultimate goal is to
run an embedded app under u-boot, exit and boot to linux.

 

I would prefer if I could run the app in SDRAM but I really don't care
where it runs as long as it works.

 

All help is greatly appreciated.

 

 

 

Sean Flynn Sean.Flynn at HexagonMetrology.com
<mailto:Sean.Flynn at HexagonMetrology.com> 

Senior Software Engineer

Hexagon Metrology, Inc

Brown & Sharpe division

250 Circuit Drive

North Kingstown, RI, 02852

phone:              1-401-886-2686

fax:                   1-401-886-2228

www.HexagonMetrology.us <http://www.HexagonMetrology.us> 

 

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