Diff: Device/WakeUp_STM_RTC.cpp

Revision:

9:29bdf5fed21a

Child:

15:b2a710aca356

diff -r 8d9a6ac0fba8 -r 29bdf5fed21a Device/WakeUp_STM_RTC.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Device/WakeUp_STM_RTC.cpp	Thu Jul 24 15:04:04 2014 +0000
@@ -0,0 +1,111 @@
+#ifdef TARGET_STM
+
+#include "WakeUp.h"
+#include "rtc_api.h"
+
+#define BYTE2BCD(byte)      ((byte % 10) | ((byte / 10) << 4))
+#define EXTI_RTC_LINE       (1 << 17)
+
+//Most things are pretty similar between the different STM targets.
+//Only the IRQ number the alarm is connected to differs. Any errors
+//with RTC_IRQn/RTC_Alarm_IRQn in them are related to this
+#if defined(TARGET_M4)
+#define RTC_IRQ     RTC_Alarm_IRQn               
+#else
+#define RTC_IRQ     RTC_IRQn
+#endif
+
+FunctionPointer WakeUp::callback;
+
+void WakeUp::set_ms(uint32_t ms)
+{        
+    if (!rtc_isenabled()) {      //Make sure RTC is running
+        rtc_init();
+        wait_us(250);            //The f401 seems to want a delay after init
+    }
+    
+    PWR->CR |= PWR_CR_DBP;      //Enable power domain
+    RTC->WPR = 0xCA;            //Disable RTC write protection
+    RTC->WPR = 0x53;
+    
+    //Alarm must be disabled to change anything
+    RTC->CR &= ~RTC_CR_ALRAE;
+    while(!(RTC->ISR & RTC_ISR_ALRAWF));
+    
+    if (ms == 0) {              //Just disable alarm
+        PWR->CR &= ~PWR_CR_DBP; //Disable power domain
+        RTC->WPR = 0xFF;        //Enable RTC write protection
+        return;
+    }
+    
+    //RTC prescaler + calculate how many sub-seconds should be added
+    uint32_t prescaler = (RTC->PRER & 0x7FFF) + 1;
+    uint32_t subsecsadd = ((ms % 1000) * prescaler) / 1000;
+    
+    if ((ms < 1000) && (subsecsadd < 2))
+        subsecsadd = 2;                             //At least 2 subsecs delay to be sure interrupt is called
+    
+    __disable_irq();                                //At this point we don't want IRQs anymore
+    
+    //Get current time
+    uint32_t subsecs = RTC->SSR;
+    time_t secs = rtc_read();
+    
+    //Calculate alarm values
+    //Subseconds is countdown, so substract the 'added' sub-seconds and prevent underflow
+    if (subsecs < subsecsadd) {
+        subsecs += prescaler;
+        secs++;
+    }
+    subsecs -= subsecsadd;
+    
+    //Set seconds correctly
+    secs += ms / 1000;
+    struct tm *timeinfo = localtime(&secs);
+    
+    //Enable rising edge EXTI interrupt of the RTC
+    EXTI->IMR |= EXTI_RTC_LINE;
+    EXTI->EMR &= ~EXTI_RTC_LINE;
+    EXTI->RTSR |= EXTI_RTC_LINE;
+    EXTI->FTSR &= ~EXTI_RTC_LINE;
+    
+    //Calculate alarm register values
+    uint32_t alarmreg = 0;
+    alarmreg |= BYTE2BCD(timeinfo->tm_sec)  << 0;
+    alarmreg |= BYTE2BCD(timeinfo->tm_min)  << 8;
+    alarmreg |= BYTE2BCD(timeinfo->tm_hour) << 16;
+    alarmreg |= BYTE2BCD(timeinfo->tm_mday) << 24;
+    
+    //Enable RTC interrupt
+    RTC->ALRMAR = alarmreg;
+    RTC->ALRMASSR = subsecs | RTC_ALRMASSR_MASKSS;      //Mask no subseconds
+    RTC->CR |= RTC_CR_ALRAE | RTC_CR_ALRAIE;            //Enable Alarm
+    
+    RTC->WPR = 0xFF;        //Enable RTC write protection
+    PWR->CR &= ~PWR_CR_DBP; //Disable power domain
+    
+    __enable_irq();         //Alarm is set, so irqs can be enabled again
+    
+    //Enable everything else
+    NVIC_SetVector(RTC_IRQ, (uint32_t)WakeUp::irq_handler);
+    NVIC_EnableIRQ(RTC_IRQ);    
+}
+
+
+void WakeUp::irq_handler(void)
+{
+    //Clear RTC + EXTI interrupt flags
+    PWR->CR |= PWR_CR_DBP;      //Enable power domain
+    RTC->ISR &= ~RTC_ISR_ALRAF;
+    EXTI->PR = EXTI_RTC_LINE;
+    PWR->CR &= ~PWR_CR_DBP;     //Disable power domain 
+    callback.call();
+}
+
+void WakeUp::calibrate(void)
+{
+    //RTC, we assume it is accurate enough without calibration
+}
+
+
+#endif