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comparison main.c @ 40:a38003b97de6

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Use debug cycle counter to handle delays.
author Daniel O'Connor <darius@dons.net.au>
date Mon, 01 Apr 2013 20:06:03 +1030
parents 1fdfbad9eca7
children f1cc171b06b5
comparison
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39:969bb070b181 40:a38003b97de6
348 } 348 }
349 printf("Max err = %.3f\r\n", maxerr); 349 printf("Max err = %.3f\r\n", maxerr);
350 } else if (!strcmp("assert", argv[0])) { 350 } else if (!strcmp("assert", argv[0])) {
351 assert(0 == 1); 351 assert(0 == 1);
352 } else if (!strcmp("cyc", argv[0])) { 352 } else if (!strcmp("cyc", argv[0])) {
353 // From http://forums.arm.com/index.php?/topic/13949-cycle-count-in-cortex-m3/ 353 if (argc != 2) {
354 // via http://stackoverflow.com/questions/11530593/cycle-counter-on-arm-cortex-m4-or-m3/11530829#11530829 354 fputs("Incorrect number of arguments\r\n", stdout);
355 uint32_t c1, c2, c; 355 goto out;
356 volatile uint32_t *DWT_CYCCNT = (uint32_t *)0xe0001004; 356 }
357 volatile uint32_t *DWT_CONTROL = (uint32_t *)0xe0001000; 357
358 volatile uint32_t *SCB_DEMCR = (uint32_t *)0xe000edfc; 358 delay(atoi(argv[1]));
359 359
360 *SCB_DEMCR = *SCB_DEMCR | 0x01000000; 360 fputs("Done\r\n", stdout);
361 *DWT_CONTROL = *DWT_CONTROL | 1 ; // enable the counter
362 c1 = *DWT_CYCCNT;
363 for (volatile int i = 0; i < 1000; i++)
364 ;
365 c2 = *DWT_CYCCNT;
366 if (c2 > c1)
367 c = c2 - c1;
368 else {
369 c = (0xffffffff - c1) + c2;
370 }
371 printf("Took %ld cycles\r\n", c);
372 } else if (!strcmp("zz", argv[0])) { 361 } else if (!strcmp("zz", argv[0])) {
373 NVIC_SystemReset(); 362 NVIC_SystemReset();
374 } else { 363 } else {
375 printf("Unknown command\r\n"); 364 printf("Unknown command\r\n");
376 } 365 }