Good day. Question about STM32L051C8 and PA11-PA12 ports.

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Posted on December 23, 2016 at 13:32

Good day. I use STM32L051C8. And I have a problem with GPIOs PA11 and PA12 in push-pull mode. When I trying set signal in 1, it up on short time and drop back. Other ports works perfect, but I can't understand what with these.

#stm32l0

[Seb]

Posted on December 23, 2016 at 14:13

The datasheet does show that PA11 and PA12 are typical GPIO:

PA11 = SPI1_MISO, EVENTOUT, USART1_CTS, COMP1_OUT

PA12 = SPI1_MOSI, EVENTOUT, USART1_RTS_DE, COMP2_OUT

Use debugger to look at your code. After tuning on the PA11 and PA12 ports, put a breakpoint to stop all SW (including interrupt). Then check with oscilloscope or multimeter what happen to the pin.

With so little info, there are many possibilities in mis-managing GPIOs.

The most popular mistakes are:

- The same GPIO are used by 2 different functions, sometime one of them is an interrupt based function

- Using GPIO DR directly instead of using the BSSR register (bit set or bit reset)

- Wrong GPIO pointer useage or activation of an alternate function in some other part of the code

Good luck in your debug!

[Tesla DeLorean]

Posted on December 23, 2016 at 14:59

You'll need to review the pins in the context of your design, if you have things attached to them, or if they are shorted to each other, or other pins.