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TMS320F28386D: EMIF 8-bits access to external peripheral TL16C750E

Clément Letonnelier
Expert 2426 points
Part Number: TMS320F28386D
Other Parts Discussed in Thread: TL16C750E

Hello,

In our design, we interface the processor with an external TL16C750E UART peripheral.

This peripheral has an 8-bits parallel bus interface.

In my initial design, I interfaced it as stated in the datasheet/TRM, with BA[0-1] used as lower adress bits.

However, considering C28x processor is only capable of performing 16-bits accesses, correct ? In that case this might be problematic if I intend to only access a single 8-bits register.

And I guess I should rather wire it as if it was a 16 bits device, with the 8 msb driven by the pull-up/pull-down I have on my board upon read accesses. (I have those pull-up/pull-down anyways as another 16-bits memory is connnected on the bus).

Do you confirm my understanding ?

Regards,

Clément

  • +1
    TI__Guru** 109125 points

    Hi,

    Clément Letonnelier said:
    However, considering C28x processor is only capable of performing 16-bits accesses, correct ? In that case this might be problematic if I intend to only access a single 8-bits register.

    If you configure EMIF in 8bit mode then it'll split any 16bit access in to two 8bit access so it should be ok. You just need to ignore the extra 8bit of read data. 

    Clément Letonnelier said:
    And I guess I should rather wire it as if it was a 16 bits device, with the 8 msb driven by the pull-up/pull-down I have on my board upon read accesses. (I have those pull-up/pull-down anyways as another 16-bits memory is connnected on the bus).

    This also should be ok but you need to see how addressing will work because if you have connected BA[1:0] to address then it'll skip all odd address because 16bit address does not use BA[0]. It only uses BA[1].

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    Expert 2426 points

    Hi,

    Yes I could do that too, it's just requires to pay attention in the write case.

    In the second solution, I would obviously not use BA[0], our board is not yet routed so I still can change.

    Thanks for the clarification.

    Best regards,
    Clément