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Issue in MIBSPI5SIMO1 pin in TMS570LS3135 microcontroller

Other Parts Discussed in Thread: TMS570LS3135

Hello all,

We are using the TMS570LS3135 microcontroller in our application. Please let us know the pin configuration of MIBSPI5SIMO1( input/output/ high impedance) under the following condition:

1.  During system reset

2. After system reset

Also this pin has internally a programmable pull up. so is it possible to program it to be a pull down?

and what is the status of the pull up during & after reset.

  • Hello Kunmit,

    MibSPI5_SIMO[1] is in a high-impedance state during and after system reset with an internal pull-up. The pull direction during system reset and immediately after system reset is fixed and cannot be changed. Software can change this pull direction to a pull-down by writing to the MibSPI5 Pin Control Register 8 (SPIPC8 at address 0xFFF7_FC34).

    Regards, Sunil

  • Hello,

    Thank you for the reply.

    I also want to know the state of the pin during power down. what is the state of MIBSPI5_SIMO1 pin when nPORRST is being driven low and after completely low. I feel the state of the I/O pin will be high impedance after the nPORRST is completely driven low. Let me know its state during the transistion of nPORRST from high to low.

    Please refer to the above diagram for referance.


  • Kunmit,

    The nPORRST timing diagram shows the input voltage levels (for both VCC and VCCIO) when the nPORRST signal must be driven active low, both during power-up and during power-down.

    When nPORRST is asserted (low), all I/O terminals except for nRST are tri-stated with a default pull active. This pull is defined in the terminal functions table in the column titled "Default Pull State".

    For the MibSPI5_SIMO[1] terminal, this default pull state is a pull-up.

    Regards, Sunil

  • Kunmit,

    Do you have any more questions related to this topic? If not, can you please close this thread by clicking the green "Verify Answer" button?

    Thanks, Sunil

  • Hello,

    Thank you for the reply.

    I have one more question related to the pin. the MIBSPI5SIMO pin has an internal pull up which is programmable.

    Kindly let me know if we can make it to internal pulldown through software. and can it be done permanently so that while boot up it takes the configuration of programmable pulldown?

    Please refer to the below figure for details.

  • Kunmit,

    The MibSPI5x I/Os will all default to being pulled up after system reset or power-on reset. The application needs to configure the MibSPI5 Pin Control Register 8 (SPIPC8 at address 0xFFF7_FC34) to change the pull direction. This will revert back to being a pull-up on any reset condition.

    If you need a pull-down on this terminal during reset and immediately after reset, you will need to add one externally.

    Regards, Sunil