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STM32F105 RTC alarm output not working

Question asked by sdt99 on Jun 18, 2015
Latest reply on Jun 19, 2015 by Clive One
I have the STM32F105 RTC alarm working correctly internal to the chip, but I cannot get the alarm to control pin PC13.

I have the BKP register configured to set the alarm output

        BKP_RTCOutputConfig(BKP_RTCOutputSource_Alarm);

and I've read the BKP memory to make sure the bit is set and BKP has not been cleared for any reason.

I have tried with and without setting PC13 to alternate function:

 GPIO_InitStruct.GPIO_Pin = GPIO_Pin_13;
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_Init(GPIOC, &GPIO_InitStruct);

But so far I have never seen the output on PC13 move when the alarm triggers.

Have I missed something obvious: there are no examples in the std peripheral library to work off.  Thanks in advance .

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