gp timer as core timer.asm

ADI 公司的DSP ADSP21262 EZ-KIT LITE开发板的全部源代码

/* Register Definitions */
#define TMSTAT (0x1400)  /* GP Timer Status Register */
#define TM0CTL (0x1401)  /* GP Timer 0 Control Register */
#define TM0PRD (0x1403)  /* GP Timer 0 Period Register */
#define TM0W   (0x1404)  /* GP Timer 0 Width Register */

/* Bit Definitions */
#define TIMODEPWM   (0x00000001)
#define PRDCNT      (0x00000008)
#define IRQEN       (0x00000010)
#define TIM0EN      (0x00000100)

/* Main code section */
.global _main;
.section/pm seg_pmco;
_main:
/* Using PWM Out mode as a core timer */

ustat3 = TIMODEPWM|     /* PWM Out Mode */
         PRDCNT|        /* Count to end of period */
         IRQEN;
dm(TM0CTL) = ustat3;

R0 = 0x8000;
dm(TM0PRD) = R0;    /* Timer 0 period = 0x8000 */

R1 = 1;
dm(TM0W) = R1;      /* Timer 0 Pulse width = 1 */

R0 = TIM0EN;            /* enable timer 0 */
dm(TMSTAT) = R0;

/* Get start clock count */
R1 = EMUCLK;

// Wait until TIM0IRQ is set
// Alternatively, we could test GPTMR0I in IRPTL
r0=dm(TMSTAT);
btst r0 by 0;
if not sz jump (pc,2);
jump(pc,-3) (db);

/* Get end clock count */
R2=EMUCLK;

/* Subtract the start count from the end count 
to obtain the number of cycles before the interrupt */
R4=R2-R1;

// R4 will be double the value of TM0PRD

_main.end: jump(pc,0);