DS90UB934-Q1: Margin Analysis result review

Hello, 

Yes, the MAP result here would be considered passing.

In general, TI recommends having a margin of at least three EQ levels with four passing strobe positions, including a contiguous rectangle of passing states that measures two EQ levels by four strobe positions.

The rectangle here would be EQ levels 0 and 1, with the third EQ level being EQ 6. 

The application note here documents more in depth Margin Analysis Program results: FPD-Link Margin Analysis Program (MAP) user's guide

Typically we would expect to see more margin when using the DS90UB934. Would you be able to share what the cable type being used is here? 

Best,

Zoe

Hi Zoe,

Thanks for the reply, the cable we are using is a 4m RG58 coax cable connect to DS90UB934.. 

Because we have 8 camera ports on our system, each port has similar but different margin analysis result.

Even the same port, the result is a little different each time. Sometimes EQ6 can pass, and sometimes EQ5 can pass.

Please reference the test results below, I test the same port and the same cable 3 times and the results are different.

So it's hard to choose EQ5 or EQ6 as the third EQ level.

And we want to use the same EQ table for all 8 camera port.

Is there any way to increase the EQ range (possibly to EQ2), so that we can have solid EQ table?

https://www.dropbox.com/scl/fi/gthu1nwdw74hdc3ssyyj0/1.jpg?rlkey=zwykwkvd9hfzklt2vj38ewee0&st=0x32y2vq&dl=0

https://www.dropbox.com/scl/fi/03yosn6d7gekchutn9xqx/2.jpg?rlkey=7r3yt9934puxx52d9nnp3vdf3&st=9k22rx7q&dl=0

https://www.dropbox.com/scl/fi/6br9mrgamm9g566pnrzfj/3.jpg?rlkey=981rg2zabvocluhmaj9711tb0&st=7o2ulzuw&dl=0

Hi Joe,

The AEQ max and floor can be changed in register 0xD5.You can do this by setting register 0xD5=0x0F. 

The EQ setting can also be manually set by disabling AEQ in register 0xD4[0].

Best,

Zoe

HI Zoe,

We set the register 0xD5 = 0x0F (and also tried 0xD5=0xF0), but the margin analysis result is still bad.

We wish to increase the green area. (The bigger the better!)

Could you give us some suggestion?

BTW, we another question.

We have tried different length cable, it seems that the longer cable have better EQ range.

The shorter cable should have better signal quality, but why it's EQ range worse than the longer cable?

4m cable

8m cable

14m cable

Hi Zoe,

Could you help us review the schematic & layout & give us some suggestions? Thanks!

Hi Joe, 

Yes, feel free to post these in this thread or send via E2E private messaging. 

Best,

Zoe

Hi Zoe,

I've send you the download link for schematic & brd file via private message.

Please help to check it, thanks!

Joe

Hi Joe, 

Provided some initial schematic feedback in private message. 

Let's keep this thread for discussing MAP results. 

Best,

Zoe