Posted on May 17, 2011 at 12:59Hi
I'm testing RTC in this way:
1) in debug mode i read RTC using RTCTimer=RTC_GetCounter();
2) next i restart and check in again; RTCTimer value is match with time
3) tourn off debug and powrer supply- now RTC is powered from 3.3V battery
4) do 1) again and RTCTimer is 20000-30000 times greater then should; i use 32.768 kHz LSE
Before reading RTCTimer=RTC_GetCounter() i execute:
static void RTC_Configuration(void)
{
/* PWR and BKP clocks selection ----------*/
RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);
/* Allow access to BKP Domain */
PWR_BackupAccessCmd(ENABLE);
/* Reset Backup Domain */
//BKP_DeInit();
/* Enable the LSE OSC */
RCC_LSEConfig(RCC_LSE_ON);
/* Wait till LSE is ready */
while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET)
{
}
/* Select the RTC Clock Source */
RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);
/* Enable the RTC Clock */
RCC_RTCCLKCmd(ENABLE);
RTC_EnterConfigMode();
BKP_RTCOutputConfig(BKP_RTCOutputSource_Second);
/* Wait for RTC registers synchronization */
RTC_WaitForSynchro();
/* Wait until last write operation on RTC registers has finished */
RTC_WaitForLastTask();
/* Set RTC prescaler: set RTC period to 1sec */
RTC_SetPrescaler(32767); /* RTC period = RTCCLK/RTC_PR = (32.768 KHz)/(32767+1) */
/* Wait until last write operation on RTC registers has finished */
RTC_WaitForLastTask();
}
and after reading:
static void RTC_DeConfiguration(void)
{
RTC_ExitConfigMode();
RTC_WaitForSynchro();
/* Allow access to BKP Domain */
PWR_BackupAccessCmd(DISABLE);
/* PWR and BKP clocks selection ----------*/
RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, DISABLE);
}
i'm not using any low-power modes; simply i'm turning off power supply
it seems that prescaler isnt working - what is wrong?
[ This message was edited by: lordac on 16-01-2009 23:25 ]
