DS90UB947-Q1: Best way to inject faults for DES '926 and SER '947 BIST mode

bandit gangwere

Part Number: DS90UB947-Q1

I have eval boards for both the DES '926 and SER '947. I have an I2C master that is connected to the '947 SER. I can see both '947 and '926 I2C registers and set them as I wish. I can read 6 bytes at 0xF0 on the DES and get the ID string.

I want to set the system into BIST mode. The '926 register 0x24 "BIST Control" should be set to 0x03 (bit3 = 0---: use register, not pin; bits 2:1 = -01-: clock=33MHz osc; bit 0 = ---1: enable BIST). Register 0x25 is the BIST error count. So far, so good.

Issue is: there is no "formal" method of injecting faults. The '913/'914 has a specific way of injecting fault via the '914 register 0x42.

There are a couple of "gross level" things I could do: turn power off for the SER; or unplug the cable.

What I am looking for is better ways of injecting errors. For example, on the SER '947, I could (reg 0x12) change the DE polarity, change the video select, (reg 0x1F change the frequency count), (reg 0x20 change to port 1).

Question is: what is the best way to inject an error?

over 6 years ago

0 Palaniappan Manickam over 6 years ago

TI__Genius 10475 points

Bandit,
I do not think these devices have a way to inject single bit errors. There are ways to introduce gross errors without exact control by other means as you referred to. I am sending this thread to one of our experts on the 94x/92x devices so he can confirm if there are better ways to do this.

0 bandit gangwere over 6 years ago in reply to Palaniappan Manickam

Intellectual 855 points

Thank you. I am gratified I did not miss something simple...
I don't care if the method does not inject a specific number of errors - just that I can detect "true" errors.

BTW - the 0xF0 "ID" registers are fantastic - please suggest/add the concept to all of the SERDES chips for the next cut of the chips. (And to other chips as appropriate.)

Thanks ... bandit

0 Vijaya Ceekala over 6 years ago in reply to bandit gangwere

TI__Intellectual 2930 points

Bandit

Thank you. Yes we have 0xFO RevID register in all of our FPD Link products

Regards
Vijay

0 Darryl Jeong over 6 years ago

TI__Expert 4210 points

Sorry for the delay.

Unfortunately there is no way to inject a single error.

A less "gross" way of injecting error is to manually change the AEQ to manual and incrementally increase the EQ value in the 926.

This is register 0x44. Set ox44[0]=1, this sets the AEQ to disable adaptive EQ.

Increase stage 1 of the EQ; 0x44[7:5] up to 111.

To use stage 2 of the EQ; 0x44[3:1] stage 1 should be 111, then you can increment stage 2 up to 111.

Hope this helps.

0 bandit gangwere over 6 years ago in reply to Vijaya Ceekala

Intellectual 855 points

Please update your documentation. For example, the '913 documentation SNLS443D –MAY 2013–REVISED OCTOBER 2016 highest documented register is 0x35 (PLL Clock Overwrite). The '914 SNLS499B –APRIL 2016–REVISED OCTOBER 2016 highest is 0x4E.

I will try it and report the results.

0 bandit gangwere over 6 years ago in reply to Darryl Jeong

Intellectual 855 points

I will give this a try. Thanks!

0 bandit gangwere over 6 years ago in reply to Vijaya Ceekala

Intellectual 855 points

I tried it on the DS90UB913/914 - nope - a read of 6 bytes starting at 0xF0 returns trash.

I am sad....

0 bandit gangwere over 6 years ago in reply to Darryl Jeong

Intellectual 855 points

So - I have the 947 SER on the remote device and and the 926 DES on my main device.
I also have a 913 SER on my main device and a 914 DES on my remote device.

The interesting thing with the 913/914, is when I set, via the 914 from the 913 (over the back I2C channel) into BIST mode, I lose all effective communication with the 914, and I need a complete power cycle to regain it (which actually is to be expected, because something is wrong).
I still need to figure out how to set the AEQ in a bad mode - a next step.

If this is a "you cannot do that", then please advise. I will continue to ... investigate.

0 Vijaya Ceekala over 6 years ago in reply to bandit gangwere

TI__Intellectual 2930 points

I am assuming you want to find a way to make the link easily show errors and that is the reason you want to program Eq?

Regards
Vijay

0 bandit gangwere over 6 years ago in reply to Vijaya Ceekala

Intellectual 855 points

Yes - y'all suggested changing EQ. Do you have a better way?

0 bandit gangwere over 6 years ago in reply to bandit gangwere

Intellectual 855 points

Turns out the problem is clock stretching. I thought my I2C master could handle it - I was wrong.
That is my problem && I think I have solutions to it.

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DS90UB947-Q1: Best way to inject faults for DES '926 and SER '947 BIST mode