定时器中断从不用LPC1769 LPCXpresso命中LPC1769

Question

我有LPC1769 LPCXpresso和Link 2进行调试.我的开发环境是IAR。

我想体验一个简单的LED闪烁使用计时器。网络上有许多示例代码。所以，我挑选了一个为MCB1700板制作的样品。我也读过一些关于计时器如何与LPC一起工作的文章。

代码编译后，我将程序下载到设备(LPC1769)。当定时器按给定的间隔调用处理程序时，我假设LED应该闪烁。

但是，这个程序从来没有访问过TIMER0_IRQHandler。

以下是我的main.c文件中的完整代码：

#include <lpc17xx.h>

void TIMER0_IRQHandler(void);

int main(void) 
{
  // (1) Timer 0 configuration (see page 490 of user manual)
  LPC_SC->PCONP |= 1 << 1; // Power up Timer 0 (see page 63 of user manual)
  LPC_SC->PCLKSEL0 |= 1 << 2; // Clock for timer = CCLK, i.e., CPU Clock (page 56 user manual)
  // MR0 is "Match Register 0". MR0 can be enabled through the MCR to reset
  // the Timer/Counter (TC), stop both the TC and PC, and/or generate an interrupt
  // every time MR0 matches the TC. (see page 492 and 496 of user manual)

  LPC_TIM0->MR0 = 500; //Toggle Time in mS
  //LPC_TIM0->MR0 = 1 << 23; // Give a value suitable for the LED blinking

  // frequency based on the clock frequency
  // MCR is "Match Control Register". The MCR is used to control if an
  // interrupt is generated and if the TC is reset when a Match occurs.
  // (see page 492 and 496 of user manual)
  LPC_TIM0->MCR |= 1 << 0; // Interrupt on Match 0 compare
  LPC_TIM0->MCR |= 1 << 1; // Reset timer on Match 0
  // TCR is "Timer Control Register". The TCR is used to control the Timer
  // Counter functions. The Timer Counter can be disabled or reset
  // through the TCR. (see page 492 and 494 of user manual)
  LPC_TIM0->TCR |= 1 << 1; // Manually Reset Timer 0 (forced);
  LPC_TIM0->TCR &= ~(1 << 1); // Stop resetting the timer
  // (2) Enable timer interrupt;
  // TIMER0_IRQn is 1, see lpc17xx.h and page 73 of user manual
  NVIC_EnableIRQ(TIMER0_IRQn); // see core_cm3.h header file
  // (3) Some more one-time set-up's;
  LPC_TIM0->TCR |= 1 << 0; // Start timer (see page 492 and 494 of user manual)
  LPC_SC->PCONP |= ( 1 << 15 ); // Power up GPIO (see lab1)
  LPC_GPIO1->FIODIR |= 1 << 29; // Put P1.29 into output mode. LED is connected to P1.29
  // (4) infinite loop;
  while (1) // Why do we need this?
  {
    //LPC_GPIO1->FIOPIN ^= 1 << 29; // Toggle the LED (see lab1)
  }
  return 0;
}


// Here, we describe what should be done when the interrupt on Timer 0 is handled;
// We do that by writing this function, whose address is “recorded” in the vector table
// from file startup_LPC17xx.s under the name TIMER0_IRQHandler;
void TIMER0_IRQHandler(void)
{
  // IR is "Interrupt Register". The IR can be written to clear interrupts. The IR
  // can be read to identify which of eight possible interrupt sources are
  // pending. (see page 492 and 493 of user manual)
  if ( (LPC_TIM0->IR & 0x01) == 0x01 ) // if MR0 interrupt (this is a sanity check);
  {
    LPC_TIM0->IR |= 1 << 0; // Clear MR0 interrupt flag (see page 492 and 493 of user manual)
    LPC_GPIO1->FIOPIN ^= 1 << 29; // Toggle the LED (see lab1)
  }
}

任何指针都将不胜感激。

编辑

供将来有类似问题的人参考，这是我的工作代码；

我用我从各地收集到的知识重写了一遍。现在它起作用了，所有处理程序都会被触发。这一次我想用多个计时器进行测试。下面是两个Timer-IRQ和SysTick的实现。

#include "LPC17xx.h"

#define SBIT_TIMER0  1
#define SBIT_TIMER1  2

#define SBIT_MR0I    0
#define SBIT_MR0R    1

#define SBIT_CNTEN   0

#define PCLK_TIMER0  2
#define PCLK_TIMER1  4    

#define LED1         0 // P2_0
#define LED2         1 // P2_1

#define MiliToMicroSec(x)  (x*1000)  /* ms is multiplied by 1000 to get us*/

extern unsigned int SystemCoreClock;
unsigned int getPrescalarForUs(uint8_t timerPclkBit);

static int data_main = 0;
static int data_systick = 0;

void Delay(uint32_t Dly)
{
   for(volatile uint32_t j = Dly; j; j--) { }
}

void SysTick_Handler(void)
{
   data_systick += 10;
}

int main (void) 
{
    SystemInit();

    LPC_SC->PCONP |= (1<<SBIT_TIMER0) | (1<<SBIT_TIMER1); /* Power ON Timer0,1 */

    LPC_TIM0->MCR  = (1<<SBIT_MR0I) | (1<<SBIT_MR0R);     /* Clear TC on MR0 match and Generate Interrupt*/
    LPC_TIM0->PR   = getPrescalarForUs(PCLK_TIMER0);      /* Prescalar for 1us */
    LPC_TIM0->MR0  = MiliToMicroSec(100);                 /* Load timer value to generate 100ms delay*/
    LPC_TIM0->TCR  = (1 <<SBIT_CNTEN);                    /* Start timer by setting the Counter Enable*/
    NVIC_EnableIRQ(TIMER0_IRQn);                          /* Enable Timer0 Interrupt */

    LPC_TIM1->MCR  = (1<<SBIT_MR0I) | (1<<SBIT_MR0R);     /* Clear TC on MR0 match and Generate Interrupt*/
    LPC_TIM1->PR   = getPrescalarForUs(PCLK_TIMER1);      /* Prescalar for 1us */
    LPC_TIM1->MR0  = MiliToMicroSec(500);                 /* Load timer value to generate 500ms delay*/
    LPC_TIM1->TCR  = (1 <<SBIT_CNTEN);                    /* Start timer by setting the Counter Enable*/
    NVIC_EnableIRQ(TIMER1_IRQn);                          /* Enable Timer1 Interrupt */

    LPC_GPIO2->FIODIR = (1<<LED1) | (1<<LED2);            /* Configure the LED pins(P2_0,P2_1) as outputs */

    SysTick_Config(900000);

    while(1)
    {
        data_main++;       
    }
}


void TIMER0_IRQHandler(void)
{
    unsigned int isrMask;

    isrMask = LPC_TIM0->IR; 
    LPC_TIM0->IR = isrMask;         /* Clear the Interrupt Bit */

    LPC_GPIO2->FIOPIN ^= (1<<LED1); /* Toggle the LED1 (P2_0) */
}


void TIMER1_IRQHandler(void)
{
    unsigned int isrMask;

    isrMask = LPC_TIM1->IR;
    LPC_TIM1->IR = isrMask;        /* Clear the Interrupt Bit */

    LPC_GPIO2->FIOPIN ^= (1<<LED2); /* Toggle the LED2 (P2_1) */
}


unsigned int getPrescalarForUs(uint8_t timerPclkBit)
{
    unsigned int pclk,prescalarForUs;
    pclk = (LPC_SC->PCLKSEL0 >> timerPclkBit) & 0x03;  /* get the pclk info for required timer */

    switch ( pclk )                                    /* Decode the bits to determine the pclk*/
    {
    case 0x00:
        pclk = SystemCoreClock/4;
        break;

    case 0x01:
        pclk = SystemCoreClock;
        break; 

    case 0x02:
        pclk = SystemCoreClock/2;
        break; 

    case 0x03:
        pclk = SystemCoreClock/8;
        break;

    default:
        pclk = SystemCoreClock/4;
        break;  
    }

    prescalarForUs =pclk/1000000 - 1;                    /* Prescalar for 1us (1000000Counts/sec) */

    return prescalarForUs;
}

Answer 1

我运行了您的代码，我可以告诉您，TIMER0_IRQHandler确实正在执行，至少对我来说是这样。要证明这一点，请尝试运行IAR调试器并在行中设置一个“断点”：

void TIMER0_IRQHandler(void)

每次输入函数时，程序都会在此函数调用时暂停。

对于lpc1769的低级函数调用，我没有太多的经验，但是我可以看到，代码中的问题就在这里：

LPC_TIM0->MR0 = 500; //Toggle Time in mS
//LPC_TIM0->MR0 = 1 << 23; // Give a value suitable for the LED blinking

匹配寄存器MR0没有预售值，因此它不是每500 mS执行一次，而是每500 uS执行一次。这类似于创建一个PWM信号，这将使LED闪烁得如此之快，以至于肉眼看不到。您可以尝试更多地了解如何使用LPC_TIM0->PR设置预销售值，以将计时器/计数器的值增加到大于1U。在没有使用预售的情况下，我每1秒就可以通过设置：

LPC_TIM0->MR0 = 100000000;

此外，确保你有一个电阻在你的LED电路，所以你不油炸它。确保您设置的输出引脚P1.29连接到板上的正确位置(PAD 12?)：LPC Xpresso Pinout

希望这能有所帮助！