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DS80PCI102: Automatic Rate-Detect

K.Yaita
Guru 29710 points
Part Number: DS80PCI102

Hi Team,

My customer sometimes saw DS80PCI102 detects the wrong rate using Automatic Rate-Detect.
DS80PCI102 detects Gen2 although Gen1 is actual.

1)
Is there any way to re-enable rate detection when DS80PCI102 detects the wrong rate?
Should we toggle the power supply in this case?

2)
Could you tell me how DS80PCI102 distinguishes Gen1 or Gen2 or Gen3 in Automatic Rate-Detect?

Best Regards,
Yaita

  • +1
    TI__Guru* 93670 points

    Hi Yaita-San,

    1). Since customer can detect rate, it means they have SMBus access. In this case, they can power down and up the channel through registers(0x02[0] and 0x01[1:0]).

    2). There is rate detector filter on input distinguishing these three rates.

    Regards,, Nasser 

  • 0 in reply to Nasser Mohammadi
    Guru 29710 points

    Hi Nasser-san,

    Thank you always for your support.

    My customer tried sending commands power down and up the channel as you referred.
    Then, he found some wait time is required to improve as the following.
    1) power down -> power up: NG (still wrong detection)
    2) power down -> 10ms wait -> power up: OK (correct detection)

    Regarding 1), there is 300us between the power down command is sent and power up command is sent because of SMBus access time.
    Do you know how much time is required to complete the power down for DS80PCI102?

    In addition, do you have the experience that DS80PCI102 detects the wrong rate using Automatic Rate-Detect? 
    The background of the question is I would like to know the workaround if you have one.

    Best Regards,
    Yaita

  • +1 in reply to K.Yaita
    TI__Guru* 93670 points

    Hi Yaita-San,

    1). This parameter has not been characterized - length of time to power down. Perhaps your customer can measure from SMBus command to current drop and then add 25 to 30% for part to part variation.

    2). I checked other customer reports related to the PCIe devices such as DS80PCI102 or PCI102 device and was not able to find any report of false rate detection.

    Regards,, nasser

  • 0 in reply to Nasser Mohammadi
    Guru 29710 points

    Hi Nasser-san,

    Thank you for your support! I understand.

    Is there recommended sequence to set the power down/up register?
    For example,  it is recommended to set other registers first and power down/up at the end, etc.
    You don't have to consider false rate detection in this case.
    I believe there isn't because the datasheet doesn't show any recommendation about the sequence to set registers.

    Best Regards,
    Yaita

  • +1 in reply to K.Yaita
    TI__Guru* 93670 points

    Hi Yaita-San,

    There is not a sequence to set the power down and up bit. 

    Regards,, Nasser