[ECOS] how to get minimum resolution

sandip sandip@masibus.com
Sat Aug 11 04:29:00 GMT 2007

dear friend ,
here i send my code, using alarm i am going to drive seven segment display.
cyg_alarm_initialize(test_alarmH, cyg_current_time()+1, 1);
using this i provide minimum delay and function call in short time.but i
didn't get small delay.

i think test_alarm_func() awke every 30 milisecond.
how  can i reduce time of alarm.

In our other product we are using timer interrupt for update seven-segment
at 50HZ 
and how to use timer interrupt in ECOS.  
#include <cyg/kernel/kapi.h>
#include <stdio.h>
#include <cyg/io/io.h>  
#include <cyg/hal/hal_arch.h>
#include <cyg/io/serialio.h>
# include <cyg/hal/hal_platform_ints.h>
#define NTHREADS 1
#define STACKSIZE 4096

#define alfabets      0x00000057
#define alfabeta      0x000000cf 
#define alfabetn      0x0000004c
#define alfabetd      0x000000dc
#define alfabety      0x000000d6
#define anode1        0x00000100
#define anode2        0x00000200
#define anode3        0x00000400
#define anode4        0x00000800
#define anode5        0x00001000
static cyg_handle_t thread[NTHREADS];
static cyg_thread thread_obj[NTHREADS];
static char stack[NTHREADS][STACKSIZE];
 cyg_uint32 i = 128;
 cyg_uint32 j = 0;
 cyg_uint32 k[5] = {0x00000057,0x000000cf ,0x0000004c ,0x000000dc
,0x000000d6 };
static void alarm_prog( cyg_addrword_t data );
/* we install our own startup routine which sets up
    threads and starts the scheduler */
void cyg_user_start(void)
HAL_WRITE_UINT32(AT91_PIOB + AT91_PIO_PER,0x00ffffff);
HAL_WRITE_UINT32(AT91_PIOB + AT91_PIO_OER,0x00ffffff);
HAL_WRITE_UINT32(AT91_PIOB + AT91_PIO_SODR,0x00ffffff);
  cyg_thread_create(4, alarm_prog, (cyg_addrword_t) 0,
      "alarm_thread", (void *) stack[0],
      STACKSIZE, &thread[0], &thread_obj[0]);
/* we need to declare the alarm handling function (which is
   defined below), so that we can pass it to
   cyg_alarm_initialize() */
cyg_alarm_t test_alarm_func;
/* alarm_prog() is a thread which sets up an alarm which is then
   handled by test_alarm_func() */
static void alarm_prog(cyg_addrword_t data)
  cyg_handle_t test_counterH, system_clockH, test_alarmH;
  cyg_tick_count_t ticks;
  cyg_alarm test_alarm;
  unsigned how_many_alarms = 0, prev_alarms = 0, tmp_how_many;
  system_clockH = cyg_real_time_clock();
  cyg_clock_to_counter(system_clockH, &test_counterH);
  cyg_alarm_create(test_counterH, test_alarm_func,
     (cyg_addrword_t) &how_many_alarms,
     &test_alarmH, &test_alarm);
  cyg_alarm_initialize(test_alarmH, cyg_current_time()+1, 1);
  /* get in a loop in which we read the current time and
     print it out, just to have something scrolling by */
  for (;;) {
    ticks = cyg_current_time();
    //printf("Time is %llu\n", ticks);
    /* note that we must lock access to how_many_alarms, since the
       alarm handler might change it.  this involves using the
       annoying temporary variable tmp_how_many so that I can keep the
       critical region short */
    tmp_how_many = how_many_alarms;
    if (prev_alarms != tmp_how_many) {
      //printf("  ---> alarm calls so far: %u\n", tmp_how_many);
      prev_alarms = tmp_how_many;
/* test_alarm_func() is invoked as an alarm handler, so
   it should be quick and simple.  in this case it increments
   the data that is passed to it. */
void test_alarm_func(cyg_handle_t alarmH, cyg_addrword_t data)
  ++*((unsigned *) data);

 HAL_WRITE_UINT32(AT91_PIOB + AT91_PIO_SODR,0x00ffffff);
 HAL_WRITE_UINT32(AT91_PIOB + AT91_PIO_CODR,k[j]|i*2);

if(j == 5)


Masibus Process Instruments (P) Ltd, Gandhinagar, India

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