TimerInterruptExample

Published 09 Feb 2010, by Simon Ford

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main.cpp

00001 // Example to set up an interrupt based on the LPC TIMER0 match register, sford
00002  
00003 #include "mbed.h"
00004 
00005 DigitalOut myled(LED1);
00006 DigitalOut irqled(LED2);
00007 
00008 void myhandler() {
00009     // do something!
00010     irqled = !irqled;
00011     
00012     // clear the TIMER0 interrupt
00013     LPC_TIM0->IR = 1;
00014 }
00015 
00016 int main() {
00017     // power up TIMER0 (PCONP[1])
00018     LPC_SC->PCONP |= 1 << 1; 
00019 
00020     // reset and set TIMER0 to timer mode
00021     LPC_TIM0->TCR = 0x2;  
00022     LPC_TIM0->CTCR = 0x0; 
00023     
00024     // set no prescaler
00025     LPC_TIM0->PR = 0;
00026 
00027     // calculate period (1 interrupt every second)
00028     uint32_t period = SystemCoreClock / 4; 
00029 
00030     // set match register and enable interrupt    
00031     LPC_TIM0->MR0 = period;
00032     LPC_TIM0->MCR |= 1 << 0;    // interrupt on match
00033     LPC_TIM0->MCR |= 1 << 1;    // reset on match
00034 
00035     // enable the vector in the interrupt controller
00036     NVIC_SetVector(TIMER0_IRQn, (uint32_t)&myhandler);
00037     NVIC_EnableIRQ(TIMER0_IRQn);
00038 
00039     // start the timer
00040     LPC_TIM0->TCR = 1;
00041 
00042     // hang around!   
00043     while(1) {
00044         myled = 1;
00045         wait(0.2);
00046         myled = 0;
00047         wait(0.2);
00048     }
00049 }