uint32_t USTIMER0_init(void)
{
    // configure timer 0 for free run.
    // 32-bit unchained mode, timer3:4 /12 prescaler.

    // enable muxed pins as gpio outputs and disable all related interrupts.
    // would need to also setup the pinmux register to select the gpio
    // function of these pins in order to use as gpio.
//   TMR0->GPINT_GPEN = GPENO12 | GPENI12;
//  TMR0->GPDATA_GPDIR = GPDIRO12 | GPDIRI12;

   // stop and reset timer.
   TMR0->TGCR = 0x00000000;
   TMR0->TCR = 0x00000000;

   // disable interrupts and set emulation to free run.
   TMR0->INTCTLSTAT = 0;
   SETBIT(TMR0->EMUMGT, SOFT | FREE);

   // config timer0 in 32-bit unchained mode.
   // remove timer0 - 3:4 from reset.
   SETBIT(TMR0->TGCR, PRESCALER(TIMER_DIV - 1) | TIMMODE_32BIT_UNCHAINED /*| TIM34RS*/ );

   // init timer0 - 1:2 period....use full range of counter.
   TMR0->TIM34 = 0x00000000;
   TMR0->PRD34 = 0x00000000;
// TMR0->PRD34 = 0xFFFFFFFF;

   TMR0->TIM12 = 0x00000000;
   TMR0->PRD12 = 0x00000000;
   // start timer0 - 3:4.
// SETBIT(TMR0->TCR, ENAMODE34_CONT);

   return (ERR_NO_ERROR);
}


void USTIMER0_delay(uint32_t in_delay)
{
    uint32_t regData;
#if 0

    // stop the timer, clear int stat, and clear timer value.
    CLRBIT(TMR0->TGCR, TIM34RS);
    TMR0->TCR = 0x00000000;
    SETBIT(TMR0->INTCTLSTAT, PRDINTSTAT34);
    TMR0->TIM34 = 0x00000000;

    // setup compare time.

    TMR0->PRD34 = TICKS_PER_US * in_delay;

    // start timer1 - 3:4 to run once up to the period.
    SETBIT(TMR0->TCR, ENAMODE34_ONETIME);
    SETBIT(TMR0->TGCR, TIM34RS);

    // wait for the signal that we have hit our period.
    while (!CHKBIT(TMR0->INTCTLSTAT, PRDINTSTAT34));
#else
    // stop the timer, clear int stat, and clear timer value.
    CLRBIT(TMR0->TGCR, TIM12RS);
    TMR0->TCR = 0x00000000;
    SETBIT(TMR0->INTCTLSTAT, PRDINTSTAT12);
    TMR0->TIM12 = 0x00000000;

    // setup compare time.
    TMR0->PRD12 = TICKS_PER_US * in_delay;

    CLRBIT(TMR0->TCR,CLKSRC12);
    CLRBIT(TMR0->TCR,TIEN12);

    // start timer1 - 3:4 to run once up to the period.
    SETBIT(TMR0->TCR, ENAMODE12_ONETIME);
    SETBIT(TMR0->TGCR, TIM12RS);

    // wait for the signal that we have hit our period.
    while (!CHKBIT(TMR0->INTCTLSTAT, PRDINTSTAT12));
#endif
}

主函数

main()
{
    USTIMER0_init();
    printf("the timer0 test start " );
    USTIMER0_delay(100);
    printf("the timer0 test end ");
}