DS110DF410/111 - Eye Open Monitor

Kawai-San,

1). Please note the customer can read HEO and VEO to show the eye opening. This is like a register read.

2). If using ALP GUI and the EVM then all you need is mini USB connector that you connect to the EVM.

3). There is a detailed description of the EOM in the data sheet. Additionally please take a look at LMH0376 data sheet as well. In this data sheet there is a detailed description. Please let us know the confusing part or what is not clear to the customer.

Regards,,nasser 

Nasser-san,

Thank you for the comments.

Please let me ask you  for the followings.

  1). I understand one could read HEO/VEO at ADR 0x27 and 0x28. How can you determine if you have enough Eye opening or not ?

  2). Yes, I understand this. How about ALP GUI + Customer Board

  3). I could not download the LMH0376 Datasheet from the WEB. It was only 4 page preview datasheet.

Best Regards,

Kawai

Kawai-San,

1). Based on device jitter tolerance, after the FR4 EQ, then you can determine if you have enough eye opening. Normally, the customers during their development they would know the maximum jitter tolerance of their system and then check the HEO and VEO to determine the best value before they get bit error in their system.

2). ALP GUI is written in Python and customers can read this code to get the detailed information. Also, they can send us questions if there is an issue or if they need more clarifications.

3). I understand. Please download LMH0366 data sheet. This has a detailed description of the eye monitor.

Regards,,nasser

Nasser-san,

1) What is the calculation to translate the HEO/VEO register value to voltage and UI information ?
     Also, how do you determine if this calculated result has enough margin or not ?

2) Where can you get this code file ?

3) I will check LMH0366 datasheet.

Best Regards,
Kawai

Hi Kawai-San,

I am looking into this and will have some feedback by tomorrow.

Thanks,,nasser

Hi Kawai-San,

There are three types of jitters and here is a quick description and how they are treated when using DS110DF410:

1). Intersymbol Interference: This can be either correlated to the data steam or the data transmission media. These media could be either FR4 PCB traces or cables used for the data transmission. The DS110DF410 FR4 equalizer cleans up this jitter and afterward the retimer measures the eye opening(i.e HEO and VEO). For example the eye could be completely closed but the reverse transfer function presented by front end equalizer of DS110DF410 can open up the eye and HEO may show high value(eye very open).

2). Random Jitter: Unlike deterministic jitter, the random jitter is caused by noise in the electrical circuit caused by thermal noise. The DS110DF410 equalizer cannot clean this up but the retimer is able to attenuate this jitter and will report this as part of HEO and VEO.

3). Sinusoidal Jitter: This is Deterministic Jitter component that has a sinusoidal or periodic from and is related to the data pattern being used. The source of sinusoidal jitter is interference from signals that are related or harmonics of the data pattern being used. The DS110DF410 retimer measures the sinusoidal jitter and reports this as part of it’s HEO/VEO measurements.

When reporting HEO/VEO the higher the number the more eye opening. For example, when HEO is 60 decimal this indicates complete eye opening(i.e no jitter). On the other hand when you are reading a low value like less than 10 decimal this indicates small eye opening like 0.25-0.3UI eye opening. Normally customers during their system evaluations and based on their requirements they would know the overall system jitter tolerance. The thought is to set HEO/VEO threshold such that they would have some margin with respect to their overall system jitter tolerance.  This is application to application dependent.

Regards,,,nasser

Nasser-san,

I apologize for my delay.

Thank you for the above explanation. So, how about the answers for the below questions ?

1) Is there a calculation formula to translate HEO value to UI value and VEO value to voltage ?

2) Where can you get the Python code file ?

Best Regards,

Kawai

Hi Kawai-San,

I am working on putting together a procedure for EOM measurements. I am expecting to have this ready within the next two days.

Regards,,nasser

Nasser-san,

Thank you for your cooperation.

I'm looking forward to hearing from you.

Best Regards,
Kawai

Hello Nasser,

Did you ever put together an EOM procedure? We are using the DS125RT410 for measurement of the Eye Opening and having troubles getting it correct. Your guide would be most helpful.

Regards,
Tom Holden

Hi Kawai,

Moving forward I would recommend using the newer SigCon Architect GUI for retimer evaluation. The GUI installer as well as the updater files for DF410/DF111 can all be downloaded via TI.com. In terms of communication to the retimer. You would need a USB2ANY or DPS_Dongle, whose two-wire serial pins then connect to SCL/SDA/GND pins on the EVM header.

www.ti.com/.../sigconarchitect

SigCon Architect allows the user to easily generate eye opening plots. The DS1xxDF410 EVK user's guide, downloadable via TI.com, has details on it.

www.ti.com/.../technicaldocuments

Regards,

Rodrigo Natal

DPS Applications Engineer

Hi Tom,

See details below for perfoming an Eye Monitor capture with TI retimer.

 Plotting an Eye Diagram

The Eye Opening Monitor is capable of plotting an equalized, but non-retimed eye to represent the quality

of signal that is going into the CDR block. This feature is useful for diagnosing gross signal integrity errors. The eye plot generated by the EOM cannot be used to extrapolate performance to bit error rates beyond 1e-7.

The EOM generates the eye plot according to a 64 x 64 matrix. Each grid space in the matrix consists of a 16-bit word that represents the number of times the incoming data stream touches that particular phase and voltage level. The EOM under-samples the incoming data stream by recording the total hit count for

each combination of phase and voltage, one grid space at a time.To configure the EOM to plot the eye diagram, sometimes called fast eye capture, use the following registers.

Step	Register[bits]	Value	Description
1	0x67[5]	0	Disable lock EOM lock monitoring
2	0x2C[6] 0x11[7:6]	0 2’b xx	Set the desired EOM vertical range as 2’b xx
3	0x11[5]	0	Power on the EOM
4	0x24[7]	1	Enable fast EOM
5	0x24[0] 0x25 0x26	1	When 24[0] is 1 begin read out of the 64 x 64 array, discard first 4 bytes This bit is self-clearing.
6	0x24[0] 0x25 0x26	1	Continue reading information until the 64 x 64 array is complete.
7	0x67[5] 0x2C[6] 0x11[5] 0x24[7]	1 1 1 0	Return the EOM to its original state. Undo steps 1-4

The data recorded from the Eye Opening Monitor (EOM) begins at (X, Y) position (0, 0) and proceeds to position (0, 63). Next, the Y-value is reset to 0 and the X-value is incremented. This process is repeated until the entire 64 x 64 matrix is read out.

Regards,

Rodrigo Natal

DPS Applications Engineer