PYNQ PS定时器中断

定时器的应用场合

1， 时钟中断。前后台程序

2， 实现延迟。

3，计数器counter

1 Global timer counter

2 CPU private timer

2.1 timer_loader

2.2 timer_counter

2.3 timer_control

get prescaler

15:8 bits

]

set scaler

0~225分频

• 读初值，
• &~ 对应位设为0
• | 新value <<8位 15:8设置为新值

enable interrupt

enable autoreload

enable timer

Start Timer

enable bit =1

restart

re load
change the counter value simutaniously

2.4 timer_interrupt_state

3 TTC

4 code

4.1 global timer

s32 usleep(u32 useconds)
{
	XTime tEnd, tCur;
	XTime_GetTime(&tCur);
	tEnd = tCur + (((XTime) useconds) * COUNTS_PER_USECOND);
	do
	{
		XTime_GetTime(&tCur);
	} while (tCur < tEnd);

	return 0;
}

实现思路就是先获取现在的时刻tCur，之后计算延迟了useconds之后的时刻tEnd，之后不断询问定时器当前时刻，随着时间流逝就会到达或者超过tEnd， 此时认为延迟完成，就可以退出了。这里XTime_GetTime读的是全局时钟，后面详细说。

4.2 private timer

static XScuGic GIC; //GIC
static  XScuTimer Timer;//timer

(1) GIC 初始化，并从硬件开启

此部分通常不变

1）GIC cfg加载

使用
XScuGic_CfgInitialize(GIC, IntcConfig,
IntcConfig->CpuBaseAddress);

需要中间变量XScuGic_Config *IntcConfig; ，IntcConfig=XScuGic_LookupConfig(INTC_DEVICE_ID);

2）开启IRQ硬件的hander

Xil_ExceptionRegisterHandler(5,
		(Xil_ExceptionHandler)XScuGic_InterruptHandler,
		(void *)IntcInstancePtr);

Xil_ExceptionEnable();

int Init_Intr_System(XScuGic * IntcInstancePtr)  //一般不需要修改
{
	int Status;

	XScuGic_Config *IntcConfig;
	/*
	 * Initialize the interrupt controller driver so that it is ready to
	 * use.
	 */
	IntcConfig = XScuGic_LookupConfig(INTC_DEVICE_ID);
	if (NULL == IntcConfig) {
		return XST_FAILURE;
	}

	Status = XScuGic_CfgInitialize(IntcInstancePtr, IntcConfig,
					IntcConfig->CpuBaseAddress);
	if (Status != XST_SUCCESS) {
		return XST_FAILURE;
	}

	/* Enable interrupts from the hardware */
	Xil_ExceptionInit();
	Xil_ExceptionRegisterHandler(XIL_EXCEPTION_ID_INT,
			(Xil_ExceptionHandler)XScuGic_InterruptHandler,
			(void *)IntcInstancePtr);
	Xil_ExceptionEnable();


	return XST_SUCCESS;
}

(2) timer 连接GIC，并且使能GIC

1）GIC 连接，并提供了timer 中断后的处理程序hander TimerIntrHandler

XScuGic_Connect(GicInstancePtr, TimerIntrId,
(Xil_ExceptionHandler)TimerIntrHandler,//set up the timer interrupt
(void *)TimerInstancePtr);

static void TimerIntrHandler(void *CallBackRef)
{
    XScuTimer *TimerInstancePtr = (XScuTimer *) CallBackRef;
    XScuTimer_ClearInterruptStatus(TimerInstancePtr);
    sec++;
    printf("seconds is %d \n",sec);
}

2）使能GIC，并设置优先级

    XScuGic_Enable(GicInstancePtr, TimerIntrId);//enable the interrupt for the Timer at GIC
    XScuGic_SetPriorityTriggerType(GicInstancePtr,  TimerIntrId, 0XA0 , 3 ) ;

void Timer_Setup_Intr_System(XScuGic *GicInstancePtr,XScuTimer *TimerInstancePtr, u16 TimerIntrId)//29号
{
        XScuGic_Connect(GicInstancePtr, TimerIntrId,
                        (Xil_ExceptionHandler)TimerIntrHandler,//set up the timer interrupt
                        (void *)TimerInstancePtr);

        XScuGic_Enable(GicInstancePtr, TimerIntrId);//enable the interrupt for the Timer at GIC
        XScuGic_SetPriorityTriggerType(GicInstancePtr,  TimerIntrId, 0XA0 , 3 ) ;

 }

(3) timer 设置并使能中断

1）TimerPtr初始化

中间cfg变量 XScuTimer_Config *TMRConfigPtr; //timer config

2）四个操作

设置分频，加载计数值，自动重载，使能中断

 XScuTimer_SetPrescaler(TimerPtr,  PrescalerValue) ;
 XScuTimer_LoadTimer(TimerPtr, Load_Value);
 XScuTimer_EnableAutoReload(TimerPtr);
 XScuTimer_EnableInterrupt(TimerPtr);//enable interrupt on the timer

int Timer_init(XScuTimer *TimerPtr, u8 PrescalerValue , u32 Load_Value,u32 DeviceId)
{
     XScuTimer_Config *TMRConfigPtr;     //timer config
     TMRConfigPtr = XScuTimer_LookupConfig(DeviceId);
     XScuTimer_CfgInitialize(TimerPtr, TMRConfigPtr,TMRConfigPtr->BaseAddr);
     XScuTimer_SetPrescaler(TimerPtr,  PrescalerValue) ;
     XScuTimer_LoadTimer(TimerPtr, Load_Value);
     XScuTimer_EnableAutoReload(TimerPtr);
     XScuTimer_EnableInterrupt(TimerPtr);//enable interrupt on the timer
     return 1;
}

(4) timer 开始计时

 XScuTimer_Start(TimerPtr);