stm32f103vet6 LSE question

[Karamel]

Hi everyone,

I am trying to active internal RTC unit of stm32f103vet6 via LSE. However, LSE osc is not able to open. I am using mikroc but It doesn't matter which platform we are using.

Why can't I work it? I am publishing my codes.

Code: [Select]

char a;

char ss2;
char ss1;
char dk2;
char dk1;
char sn2;
char sn1;

char text[30] = "00:00:00";
char tempstr[2];
unsigned long time;


void main() {

  GPIO_Digital_Output(&GPIOB_BASE, _GPIO_PINMASK_8);

  UART3_Init(9600); Delay_ms(100);

  // Init power and clock for RTC
  RCC_APB1ENR.BKPEN = 1; // Backup interface clock enable
  RCC_APB1ENR.PWREN = 1; // Power interface clock enable
  PWR_CR.DBP = 1;        // Schreibschutz der BackupDomainRegister abschalten
  RCC_BDCR.RTCSEL0 = 1;  // 01: LSE oscillator clock used as RTC
  RCC_BDCR.RTCSEL1 = 0;  // 01: LSE oscillator clock used as RTC
  RCC_BDCR.RTCEN   = 1;  // RTC clock enable
  RCC_BDCR.LSEON   = 1;  // External 32 kHz oscillator ON
  while(RCC_BDCR.LSERDY == 0);   // microcontroller can not pass this code!
 
  RCC_BDCR.BDRST = 1;
 
  PWR_CR.DBP = 0;        // Schreibschutz der BackupDomainRegister einschalten

  // RTC-Register sycned?
  RTC_CRL.RSF = 0;
  while (RTC_CRL.RSF == 0);

  // Config RTC
  while (RTC_CRL.RTOFF == 0);
  RTC_CRL.CNF = 1;             // Configmode on
  RTC_PRLL = 0x7FFF;          // RTC-clock-prescaler
  RTC_CRL.CNF = 0;             // Configmode off
  while (RTC_CRL.RTOFF == 0);



    while(1)
    {
        // Burada RTC yi basacagiz
        time = RTC_CNTL;

        a = (time % 60);

        sn2 = (a / 10) + 48;
        sn1 = (a % 10) + 48;

        a = ((time/60) % 60);

        dk2 = (a / 10) + 48;
        dk1 = (a % 10) + 48;

        a = ((time/60/60) % 60);

        ss2 = (a / 10) + 48;
        ss1 = (a % 10) + 48;

        UART3_Write(ss2); Delay_ms(10); UART3_Write(ss1); Delay_ms(10); UART3_Write(':'); Delay_ms(10);
        UART3_Write(dk2); Delay_ms(10); UART3_Write(dk1); Delay_ms(10); UART3_Write(':'); Delay_ms(10);
        UART3_Write(sn2); Delay_ms(10); UART3_Write(sn1); Delay_ms(10); UART3_Write(' '); Delay_ms(10); UART3_Write(' '); Delay_ms(10); UART3_Write(' ');
        GPIOB_ODR.F8 = 1; Delay_ms(460); GPIOB_ODR.F8 = 0; Delay_ms(460);
    }

}
as you can see, microcontroller can not pass this code while(RCC_BDCR.LSERDY == 0); because, it never become ready. I am working with simple pcb. I can work with HSE and I have chaged 32.768khz crystall twice. I checked it. all connections are okay but why can not open it?

Best Regards,
Karamel 

[Karamel]

also, my microcontroller is working with HSE - 72 mhz when I am trying it.

[HackedFridgeMagnet]

Your Low speed External oscillator is not oscillating.
Possibly a hardware problem. Soldering problem, capacitance problem.
Or
Have you initialised everything you need to.
Have a look at somebody elses RTC code, you may need to set a register or run some init code that does the same.

I'm guessing that

PWR_CR.DBP = 1;        // Schreibschutz der BackupDomainRegister abschalten

is like

PWR_BackupAccessCmd( ENABLE );  /* Allow access to BKP Domain */

[plex]

I have not used the exact processor but in the STM32F4 there is a special unlock sequence after PWR_CR.DBP = 1; because the micro is probably in back up domain reset state.
This is:
RTC_WPR = 0xCA;   //unlock write protection
RTC_WPR = 0x53;   //unlock write protection

Only after that can you change the clock source.

Check the RTC initialization and configuration section of your processor reference manual very carefully.

I hope this helps.

[Karamel]

I have to ask one question, before I solve this problem.

I know that, if stm32 m3 microcontrollers run in overclock, they can be broken unit of osc.

I have broken one microprocessor like that. (HSE unit has broken) Therefore, I have to ask that, you can see my clock configuration bellow. Is it true? or Is there any overclock for any units?