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TMS320C6748: Maximum Rise time and fall time of MOSI,MISO,CS of SPI peripheral

AAAA PPPP
Expert 1410 points
Part Number: TMS320C6748

Hello,

I am using TMS320c6748 LCDK kit. I am planning to make device as SPI master to drive a slave peripheral. The SPI lines work as desired , but I have problem related to the timings of the wave. I cant find any documentation on rise and fall time of the MOSI,MISO,CS pins. The datasheet of tms320c6748 SPRS590G  gives the details of the rise and fall times of I2C peripherals only. The slave peripheral gives strict requiremnet of rise and fall times of the MOSI,MISO,CS lines as maximum 6.5ns. I checked the rise and fall time after implementing on c6748 in CRO, but it does not meet.

  Where can I get information on rise and fall times of the MOSI,MISO,CS pins of SPI peripheral in c6748?

Thanks in advance

With Regards

Shalini

  • 0
    TI__Guru**** 161600 points
    Hi Shalini,

    You say:
    he SPI lines work as desired , but I have problem related to the timings of the wave. I cant find any documentation on rise and fall time of the MOSI,MISO,CS pins


    Do you have problems communicating with the device connected on the LCDKs SPI?

    I am looping the design team to elaborate on the problem regarding the datasheet information.

    Best Regards,
    Yordan
  • 0 in reply to Yordan Kovachev
    Expert 1410 points
    Hello,

    I was able to communicate with SPI of LCDK kit to some other peripherals successfully. The strict requirement of peripheral to be communicated now is maximum rise and fall times of 6.5ns for MOSI,MISO,CS pins where DSP is master,which I think SPI doesnt meet. So I want to know how do I get information of rise and fall times of the c6748 processor outputs.

    Thanks in advance

    With regards
    Shalini
  • 0 in reply to AAAA PPPP
    Expert 1410 points
    Hello,

    please help..My problem still persist..

    With Regards
    Shalini
  • 0 in reply to AAAA PPPP
    TI__Mastermind 29270 points

    Hi Shalini,

    Sorry for the delay.

    I reached out to the team on this and they say that the max rise and fall times for all peripherals (except I2C) are covered by this Transition Time row in the Recommended Operating Conditions. Does it help?

    Regards,
    Mark

  • 0 in reply to Mark Mckeown
    Expert 1410 points
    Hello,

    This is regarding input pins. I would like to know these quantities for output pins like SPI MOSI..

    Thanks in advance

    With Regards
    Shalini
  • 0 in reply to AAAA PPPP
    TI__Mastermind 29270 points
    Shalini,

    You are correct. The transition time for inputs and outputs cannot be assumed as the same.

    The output rise/fall is a function of load and other device operating conditions.

    Can you utilize the IBIS file to extract the rise/fall times of the IO from the models provided. A simulation with the receiver buffer and PCB modeled will provide you the most accurate information. I recommend using Mentor Graphics HyperLynx.

    From the product page (below), click on Tools & Software, then download the IBIS file under Models.
    www.ti.com/.../

    Hope this helps,
    Mark