Timer interrupt never hits TIMER0_IRQHandler

senersoft — Tue, 05 Mar 2019 12:48:47 GMT

I have LPCXpresso 1769 and LPC-Link 2 for debugging. My development environment is IAR.

I wanted to experience a simple LED blinking using Timer. There are many sample codes about it and I picked one I presume it is a working sample. I have also read some here and there how timer works with LPC's, etc...

The code compiles and I downloaded the program to the device.

My question is how to debug and find the reason why TIMER0_IRQHandler doesn't get hit at all.

Here is the complete code in my main.c file:

#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)
}
}

Note that: Sorry for the code part. "Source Code <>" option didn't work for some reason.

Re: Timer interrupt never hits TIMER0_IRQHandler

soledad — Tue, 12 Mar 2019 03:13:07 GMT

Hi,

Please check the following link,

https://community.nxp.com/thread/423278

I hope this helps,

regards

Soledad

topic Timer interrupt never hits TIMER0_IRQHandler in LPC Microcontrollers

Timer interrupt never hits TIMER0_IRQHandler

Re: Timer interrupt never hits TIMER0_IRQHandler