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matic
matic
Associate III
January 30, 2016
Question

AF remap on F1 vs. F3 series

  • January 30, 2016
  • 3 replies
  • 801 views
Posted on January 30, 2016 at 23:04

In previous design, where we used STM32F103 we could have two alternate functions on the same pin. It was SPI CLK (used for SSI protocol) and TIM2_CH2 which was configured that every CLK edge reset CNT register (used for SSI timeout). That was possible because you can specify in AFIO_MAPR registers where should each peripheral be mapped.

It seems that in STM32F303 this is not possible. There you have only one field for each pin in GPIO_AFRH / GPIO_AFRL registers where you can specify which function will be connected to it.

So, is it true that here we cannot have SPI CLK and timer input configured on the same pin? Am I right? Thanks
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    3 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    January 31, 2016
    Posted on January 31, 2016 at 01:12

    Seems to be a correct interpretation 

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    Walid FTITI_O
    Walid FTITI_O
    Visitor II
    February 2, 2016
    Posted on February 02, 2016 at 12:34

    Hi obid.matic,

    We confirm that only in STM32F1xx family , the alternate function can be remapped by software to some other port pins. If several peripherals share the same I/O pin, to avoid conflict between these alternate functions only one peripheral should be enabled at a time through the peripheral clock enable bit .

    In a case similar to the one that you mentioned,

    when we have only

    one

    input signal in that pin, both alternate functions can be used to let both peripherals processing the input signal.

    In the other products families there is no IO remapping and one only alternate function is assigned to a pin.

    -Hannibal-

    matic
    maticAuthor
    Associate III
    February 2, 2016
    Posted on February 02, 2016 at 20:40

    Thanks

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