circuitpython/stm/rtc.c

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#include <stdio.h>
#include <stm32f4xx.h>
#include "misc.h"
#include "mpconfig.h"
#include "qstr.h"
#include "obj.h"
#include "rtc.h"
void rtc_init(void) {
/* Enable the PWR clock */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);
/* Allow access to RTC */
PWR_BackupAccessCmd(ENABLE);
if (RTC_ReadBackupRegister(RTC_BKP_DR0) == 0x32F2) {
// RTC still alive, so don't re-init it
// wait for RTC APB register synchronisation
RTC_WaitForSynchro();
return;
}
uint32_t timeout = 10000000;
/* Enable the PWR clock */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);
/* Allow access to RTC */
PWR_BackupAccessCmd(ENABLE);
/* Enable the LSE OSC */
RCC_LSEConfig(RCC_LSE_ON);
/* Wait till LSE is ready */
while((RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET) && (--timeout > 0)) {
}
/* If LSE timed out, use LSI instead */
if (timeout == 0) {
// Disable the LSE OSC
RCC_LSEConfig(RCC_LSE_OFF);
// Enable the LSI OSC
RCC_LSICmd(ENABLE);
/* Wait till LSI is ready */
while(RCC_GetFlagStatus(RCC_FLAG_LSIRDY) == RESET) {
}
/* Use LSI as the RTC Clock Source */
RCC_RTCCLKConfig(RCC_RTCCLKSource_LSI);
} else {
/* Use LSE as the RTC Clock Source */
RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);
}
/* Note: LSI is around (32KHz), these dividers should work either way */
/* ck_spre(1Hz) = RTCCLK(LSE) /(uwAsynchPrediv + 1)*(uwSynchPrediv + 1)*/
uint32_t uwSynchPrediv = 0xFF;
uint32_t uwAsynchPrediv = 0x7F;
/* Enable the RTC Clock */
RCC_RTCCLKCmd(ENABLE);
/* Wait for RTC APB registers synchronisation */
RTC_WaitForSynchro();
/* Configure the RTC data register and RTC prescaler */
RTC_InitTypeDef RTC_InitStructure;
RTC_InitStructure.RTC_AsynchPrediv = uwAsynchPrediv;
RTC_InitStructure.RTC_SynchPrediv = uwSynchPrediv;
RTC_InitStructure.RTC_HourFormat = RTC_HourFormat_24;
RTC_Init(&RTC_InitStructure);
// Set the date (BCD)
RTC_DateTypeDef RTC_DateStructure;
RTC_DateStructure.RTC_Year = 0x13;
RTC_DateStructure.RTC_Month = RTC_Month_October;
RTC_DateStructure.RTC_Date = 0x26;
RTC_DateStructure.RTC_WeekDay = RTC_Weekday_Saturday;
RTC_SetDate(RTC_Format_BCD, &RTC_DateStructure);
// Set the time (BCD)
RTC_TimeTypeDef RTC_TimeStructure;
RTC_TimeStructure.RTC_H12 = RTC_H12_AM;
RTC_TimeStructure.RTC_Hours = 0x01;
RTC_TimeStructure.RTC_Minutes = 0x53;
RTC_TimeStructure.RTC_Seconds = 0x00;
RTC_SetTime(RTC_Format_BCD, &RTC_TimeStructure);
// Indicator for the RTC configuration
RTC_WriteBackupRegister(RTC_BKP_DR0, 0x32F2);
}
/******************************************************************************/
/* Micro Python bindings */
mp_obj_t pyb_rtc_read(void) {
RTC_TimeTypeDef RTC_TimeStructure;
RTC_GetTime(RTC_Format_BIN, &RTC_TimeStructure);
printf("%02d:%02d:%02d\n", RTC_TimeStructure.RTC_Hours, RTC_TimeStructure.RTC_Minutes, RTC_TimeStructure.RTC_Seconds);
return mp_const_none;
}