Микроконтроллеры

может PC13 в этом случае некорректно использовать Bit 19 COSEL: Calibration output selection When COE=1, this bit selects which signal is output on RTC_CALIB. 0: Calibration output is 512 Hz 1: Calibration output is 1 Hz These frequencies are valid for RTCCLK at 32.768 kHz and prescalers at their default values (PREDIV_A=127 and PREDIV_S=255). Refer to Section 23.3.15: Calibration clock output Calibration clock output When the COE bit is set to 1 in the RTC_CR register, a reference clock is provided on the RTC_CALIB device output. If the COSEL bit in the RTC_CR register is reset and PREDIV_A = 0x7F, the RTC_CALIB frequency is fRTCCLK/64. This corresponds to a calibration output at 512 Hz for an RTCCLK frequency at 32.768 kHz. The RTC_CALIB duty cycle is irregular: there is a light jitter on falling edges. It is therefore recommended to use rising edges. When COSEL is set and “PREDIV_S+1” is a non-zero multiple of 256 (i.e: PREDIV_S[7:0] = 0xFF), the RTC_CALIB frequency is fRTCCLK/(256 * (PREDIV_A+1)). This corresponds to a calibration output at 1 Hz for prescaler default values (PREDIV_A = Ox7F, PREDIV_S = 0xFF), with an RTCCLK frequency at 32.768 kHz.