main.cpp

00001 #include "mbed.h"
00002 
00003 DigitalOut status_led(LED_BLUE);
00004 DigitalOut error_led(LED_RED);
00005 
00006 extern "C" void RTC_IRQHandler(void) {
00007     error_led = 0;
00008 }
00009 
00010 extern "C" void RTC_Seconds_IRQHandler(void) {
00011     error_led = 0;
00012 }
00013 
00014 extern "C" void HardFault_Handler(void) {
00015     error_led = 0;
00016 }
00017 
00018 extern "C" void NMI_Handler_Handler(void) {
00019     error_led = 0;
00020 }
00021 
00022 void rtc_init(void) {
00023     // enable the clock to SRTC module register space
00024     SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;
00025     SIM->SOPT1 = (SIM->SOPT1 & ~SIM_SOPT1_OSC32KSEL_MASK) | SIM_SOPT1_OSC32KSEL(0);
00026 
00027     // disable interrupts
00028     NVIC_DisableIRQ(RTC_Seconds_IRQn);
00029     NVIC_DisableIRQ(RTC_IRQn);
00030 
00031     // Reset
00032     RTC->CR = RTC_CR_SWR_MASK;
00033     RTC->CR &= ~RTC_CR_SWR_MASK;
00034 
00035     // Allow write
00036     RTC->CR = RTC_CR_UM_MASK | RTC_CR_SUP_MASK;
00037 
00038     NVIC_EnableIRQ(RTC_Seconds_IRQn);
00039     NVIC_EnableIRQ(RTC_Seconds_IRQn);
00040 
00041     printf("LR: 0x%x\n", RTC->LR);
00042     printf("CR: 0x%x\n", RTC->CR);
00043     wait(1);
00044     if (RTC->SR & RTC_SR_TIF_MASK){
00045         RTC->TSR = 0;
00046     }
00047     RTC->TCR = 0;
00048 
00049     // After setting this bit, wait the oscillator startup time before enabling
00050     // the time counter to allow the clock time to stabilize
00051     RTC->CR |= RTC_CR_OSCE_MASK;
00052     for (volatile int i=0; i<0x600000; i++);
00053 
00054     //enable seconds interrupts
00055     RTC->IER |= RTC_IER_TSIE_MASK;
00056 
00057     // enable time counter
00058     RTC->SR |= RTC_SR_TCE_MASK;
00059 
00060 
00061 }
00062 
00063 int main() {
00064     error_led = 1;
00065     rtc_init();
00066 
00067     while (true) {
00068         wait(1);
00069         status_led = !status_led;
00070         printf("%u\n", RTC->TSR);
00071     }
00072 }