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Compiler/TMS570LC4357-EP: TMS570LC4357 unused pins

Sho Kobori
Intellectual 640 points

Part Number: TMS570LC4357-EP
Other Parts Discussed in Thread: TMS570LC4357

Tool/software: TI C/C++ Compiler

Hello,

We are using TMS570LC4357.

We would like to know about wiring method of unused IO pins.

We are not using EMIF, FlaxRay and Ethernet Controller.

Can these be left unconnected?

We already checked Technical Reference Manual of the TMS570LC4357.

However, We do not find wiring method about these pin when unused. 

Could you please tell me about reference design If these pins unused.

Regards,

 

Sho 

  • 0
    TI__Guru**** 191886 points

    Hi,

      Yes, you can leave the unused IO unconnected. Normally the I/Os will have internal pullup/pulldown. Leaving them unconnected is fine. 

  • 0 in reply to Charles Tsai
    Intellectual 640 points

    Hello Charles,

    Thank you for reply.

    I understand you say, EMIF, FlaxRay and Ethernet Controller PIN has Internal pull-up/down, right?
    If there is documents described presence or absence of these Internally Pull Select, Could you please tell me about the document numbers and point of description.

    Regards,

    Sho

  • 0 in reply to Sho Kobori
    TI__Guru**** 191886 points

    Hi,

      Not sure why you rejected the answer. One thing that is lacking in the datasheet is that it didn't specifically document what to do with the unused I/Os. As I mentioned and you can find the same in the datasheet is that default pulldown/pullup states of the I/Os. 

      Below is the screenshot of the terminal function table for the Ethernet pins. You can find the rest of the pins in the terminal function table in the datasheet.

    Here is the link to the datasheet.

    https://www.ti.com/lit/gpn/tms570lc4357

  • 0 in reply to Charles Tsai
    Intellectual 640 points

    Hello Charles,


    Thank you for your reply.

    I mistake rejected your answer.

    this document is described that Default Pull State means the state of the pull applied to the terminal while nPORRST is low and immediately after nPORRST goes High.

    Default Pull State means presence or absence of Internal pull select , right?

    In addition, Pull type of this table shows Programmable or Fixed of Internal pull select(Pull-up or Pull-down), right?

    Regards,

    Sho

  • 0 in reply to Sho Kobori
    TI__Guru**** 191886 points

    Hi,

     

    this document is described that Default Pull State means the state of the pull applied to the terminal while nPORRST is low and immediately after nPORRST goes High.

      Your understanding is correct.

    Default Pull State means presence or absence of Internal pull select , right?

    If you see a default pull state specified for a pin then it is active during nPORRST and after the reset is release. You might find a few "Output Only" pins that do not have the default pull specified. For these pins, if you are not using them, you can leave them unconnected.

    In addition, Pull type of this table shows Programmable or Fixed of Internal pull select(Pull-up or Pull-down), right?

    Some of the pull state can be programmable after the reset is released. For example, you will find a GIOA[0] with a default pulldown but after reset you can program it to either pullup or pulllow. But there are other pins that the pull state is not programmable after reset.