mbed LPC1768でRTCの割り込みで1秒間隔でLチカするコードサンプル

rtc_int_blink.cpp

#include "mbed.h"

DigitalOut myled(LED1);

void led_blink(void){
    static int led = 0;
    led = !led;
    myled = led;
}

void rtc_irq_handler(void){
    __disable_irq();
    
    // reset Interrupt flag
    LPC_RTC->ILR |= 0x01;
    // RTCの未解決フラグを下ろす
    NVIC_ClearPendingIRQ(RTC_IRQn);
    
    led_blink();
    
    __enable_irq();
}

int main() {
    
    // RTCで1秒毎に割り込みを入れてLEDを点滅させる
    
    // Ensure power is on
    // 9: PCRTC
    LPC_SC->PCONP |= 0x01 << 9;
    
    // CTCRST: internal oscillator divider reset
    LPC_RTC->CCR = 0x01;
    
    // RTCCIF: Counter Increment Interrupt reset
    LPC_RTC->ILR |= 0x01;
    
    //IMSEC: When 1, an increment of the Second value generates an interrupt.
    LPC_RTC->CIIR |= 0x01;
    
    NVIC_SetVector(RTC_IRQn, (uint32_t)rtc_irq_handler);
    NVIC_SetPriority(RTC_IRQn,0);
    NVIC_EnableIRQ(RTC_IRQn);
    
    while(1);
}