void PID_Init_Timer(void) {
uint32_t ui32SystemClock;
SysCtlPeripheralEnable(PID_TIMER_PERIPH);
//设置为周期性定时器
TimerConfigure(PID_TIMER, TIMER_CFG_PERIODIC);
//设置为系统时钟 50MHz
TimerClockSourceSet(PID_TIMER, TIMER_CLOCK_SYSTEM);
ui32SystemClock = SysCtlClockGet();
//50,000-1就是1ms, 50-1就是1us
TimerLoadSet(PID_TIMER, TIMER_A, ui32SystemClock / 1000 * PID_DELAY_TIME - 1);
TimerIntRegister(PID_TIMER, TIMER_A, PIDTimerIntHandler);
TimerIntClear(PID_TIMER, TIMER_TIMA_TIMEOUT);
//开始计时
TimerEnable(PID_TIMER, TIMER_A);
//不允许处理中断（开始时开启）
TimerIntDisable(PID_TIMER, TIMER_TIMA_TIMEOUT);
}
/*
* Initializes timer to trigger an overflow interrupt every 1/SHT1X_CLOCK_HZ seconds.
* The function also configures uDMA to trigger timer's interrupt handler.
*
* If uDMA is enabled and its transaction is in progress it blocks normal interrupt
* flow of the timer.
*/
void sht1x_timer_init(void)
{
SysCtlPeripheralEnable(SHT1X_TIMER_PERIPH);
IntDisable(SHT1X_TIMER_INTERRUPT);
TimerIntDisable(SHT1X_TIMER_BASE, TIMER_TIMA_TIMEOUT);
TimerDisable(SHT1X_TIMER_BASE, SHT1X_TIMER);
TimerConfigure(SHT1X_TIMER_BASE, TIMER_CFG_A_PERIODIC);
TimerPrescaleSet(SHT1X_TIMER_BASE, SHT1X_TIMER, 0);
TimerClockSourceSet(SHT1X_TIMER_BASE, TIMER_CLOCK_SYSTEM);
TimerLoadSet(SHT1X_TIMER_BASE, SHT1X_TIMER, SHT1X_CLK_NR);
TimerDMAEventSet(SHT1X_TIMER_BASE, TIMER_DMA_TIMEOUT_A);
TimerIntClear(SHT1X_TIMER_BASE, TIMER_TIMA_TIMEOUT);
IntEnable(SHT1X_TIMER_INTERRUPT);
}