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DS80PCI810: need more information about register 0x01

Max Wu
Prodigy 30 points
Part Number: DS80PCI810


Hi Sir:

I used the linear repeater on my design for PCIe application.

as far as I know that trigger PWDN could reset RXDET as spec describe 

Power Down mode, input is Hi-Z, output drivers are disabled,

Used to reset Rx-Detect State Machine when held high for 5 µs.

My question is that clear/set register 0x01(PWDN) also could reset RXDET where same as pin control mode?

TKS,

  • 0
    TI__Mastermind 43795 points

    THi Max,

     

    The entire device terminations can be controlled with register 0x02[7:6]

     

    The sequence of register writes to reset the rxdet state machine for all 8 channels simultaneously.

     

    0x02 = 80’h

    0x02 = C0’h

    0x02 = 80’h

    0x02 = 00’h

     

    This will re-enable the rxdet state machine for all eight channels.

      

    To control the termination on less than 8 channels, the RXDET pin would need to be overridden in register 0x08. 

    Write 0x08 = 08’h

     

    Then the RXDET bits in each channel to be controlled need to be programmed with the following sequence.

    Example for CH0

     

    Write 0x0E = 00’h  (input hi-z, so the termination is shut off)

    Write 0x0E = 0C’h  (enable auto rxdet, input is high-z until output termination is detected)

     

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Prodigy 130 points

    Hi Lee

    We want to know can we set register 0x01(PWDN) to replace PWDN pin 52 ?

    Because we don't want reset all 8 channels 

    PWDN pin 52 can reset RXDET machine for all channels from datasheet mentioed , so if we set register 0x01(PWDN) also trigger reset RXDET machine,it is  the same ,right ?

    Rain

  • 0 in reply to Wu Rain
    TI__Mastermind 43795 points

    RXDET can be controlled with register 0x02[7:6]

     

    The sequence of register writes to reset the rxdet state machine for all 8 channels simultaneously.

     

    Register    Write Data

    0x02    =    80’h

    0x02    =    C0’h

    0x02    =    80’h

    0x02    =    00’h

     

    This will re-enable the rxdet state machine for all eight channels.

      

    To control the termination on less than 8 channels, the RXDET pin would need to be overridden in register 0x08. 

    Register     Write Data

    0x08     =     08’h

     

    Then the termination for each channel to be controlled needs to be programmed with the following sequence.

    Example for CH0

    Register       Write Data        Comment 

    0x0E      =      00’h               (input hi-z, so the termination is shut off)

    0x0E      =      0C’h              (input is 50 Ohm)

    Example for CH1

    Register       Write Data        Comment 

    0x15      =      00’h               (input hi-z, so the termination is shut off)

    0x15      =      0C’h              (input is 50 Ohm)

    I will look at the function of register 0x01 to see how it can replace the PWDN pin

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    TI__Mastermind 43795 points

    The ability to reduce power to individual channels is controlled with Register 0x01.  Please note that this reduced power state will not shut off the input termination on the device.

    To reset an individual channel RXDET state machine the following sequence of register writes is needed. 

    Example for CH0

    Register       Write Data        Comment 

    0x08     =        08’h              (override RXDET configuration pin

    0x0E      =      00’h               (input hi-z, so the termination is shut off)

    0x0E      =      08’h              (input is hi-z until RXDET occurs)

    Note:  Overriding the RXDET pin in Register 0x08 will initially impact all 8 channels.  After the initial changes, individual channels can be modified using the above sequence.

    Regards,

    Lee