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jean_prieur
jean_prieur
Associate III
September 19, 2013
Question

NVIC interrupts on two ports with same pin number

  • September 19, 2013
  • 7 replies
  • 3752 views
Posted on September 19, 2013 at 17:37

Hello everybody,

Is it possible to link same pin number of different GPIO ports on the same EXTI line ?

For example, create an interrupt on line_0 for the GPIO pin A0 and the pin B0. It seems impossible to achieve with the ST librairies - but I don't understand why it's impossible regarding to the internal schematic of the STM32F4... I really want to use more than 16 GPIO with interrupts. Is there a software way to perform this interruption ?

Thanks a lot !
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    7 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    September 19, 2013
    Posted on September 19, 2013 at 18:33

    NO, it uses an N-to-1 mux, only one bank's pin reaches the signal conditioning.

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    Tesla DeLorean
    Tesla DeLorean
    Guru
    September 19, 2013
    Posted on September 19, 2013 at 18:37

    0690X00000604RMQAY.png

    0690X000006051hQAA.png
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      jean_prieur
      jean_prieurAuthor
      Associate III
      September 19, 2013
      Posted on September 19, 2013 at 18:56

      Thanks Clive, I just wanted to sure.

      Tesla DeLorean
      Tesla DeLorean
      Guru
      September 19, 2013
      Posted on September 19, 2013 at 19:11

      Generally you'd use an external priority decoder to decimate the number of pins required on the CPU.

      Alternatively you could use TIMx_CHx pins in input capture mode, or poll slow GPIO sources. I'd recommend a print out of the Data Sheet with pin designations, and a high-lighter pen. Assign the TIM pins first, then the EXTI. Draw a pin vs bank matrix if that helps.
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      John F.
      John F.
      Associate III
      September 20, 2013
      Posted on September 20, 2013 at 09:09

      For example. 74HC147

      10-to-4 Line Priority Encoder

      or 74HC148

      8-Line To 3-Line Priority Encoder

      . Also CD4532 from the old CMOS 4000 series.

      Also note on the STM32F4 family (STM32F405/407xx and STM32F415/417xx) this erratum -

      Configuration of PH10 and PI10 as external interrupts is erroneous

      Description

      PH10 or PI10 is selected as the source for the EXTI10 external interrupt by setting bits

      EXTI10[3:0] of SYSCFG_EXTICR3 register to 0x0111 or 0x1000, respectively. However,

      this erroneous operation enables PH2 and PI2 as external interrupt inputs.

      As a result, it is not possible to use PH10/PI10 as interrupt sources if PH2/PI2 are not

      selected as the interrupt source, as well. This means that bits EXTI10[3:0] of

      SYSCFG_EXTICR3 register and bits EXTI2[3:0] of SYSCFG_EXTICR1 should be

      programmed to the same value:

      • 0x0111 to select PH10/PH2

      • 0x1000 to select PI10/PI2

      Workaround

      None.

      sam
      sam
      Explorer
      March 31, 2014
      Posted on March 31, 2014 at 05:01

      wish it was ORed...

      John F.
      John F.
      Associate III
      March 31, 2014
      Posted on March 31, 2014 at 09:25

      Then just use an external single OR gate such as the SN74LVC1G32DBVR (Texas version of 74LVC1G32 single OR gate). Alternatively, if you need a '0' OR (output low if either input low) the SN74LVC1G08DBVR AND gate will do.

       

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