SN75DP130: The SN75DP130DSRGZT output don't responce to the setting.

DP Re-driver.pdfPlease refer to the schematic of the appendix, thanks!

Cheng

In the screenshot you had, are you manually changing TX SWING and Pre-emphasis level of the GPU?

DP130 has its own TX SWING and Pre-emphasis settings, are you changing these settings?

Thanks

David 

David，

       Yes, now I want to change 00103H register value, but not how to modified it.

       Below is the configuration of DP130, according to the eye diagram, which bit can be modified to tune the output voltage swing and pre-emphasis? Is address 00103h bit 1:0 and bit 4:3 or other register?

picture.zip

Cheng

This is correct. Lane TX Swing and pre-emphasis is programmed through the DP130 DPCD registers (Address 00103h - 00106h). The DPCD address space is indirectly addressable through the local I2C registers.

I had a chance to take a look at your schematic and noticed DP130 is connected to both DP source connector and DP sink connector, does this imply that cable length will change between source to DP130 and DP130 to sink? If the cable length will change on either side of DP130, then DP130 is not suitable for this particular application. DP130 is best used when one side is fixed and other side changes. 

If both side cable length changes, then TDP142 will be a better device than DP130.

Thanks

David

dear  David,

       I use your advise to modify the 00103h  address value through the local I2C register, but modfiy offset "1FH" address value always not change, I want to  confirm how to modify the 00103H-00106H address value , thanks for you help.I2C value.zip