DS110DF410 How to convert 0x32,0x33,0x6A register Value to V[mV] or time[UI].

Hi

Our customer is in trouble.
I want to solve this problem quickly.

Please help us on this item.

Best Regards,

Sugiyama

Sugiyama-San,

If I understand you correctly, the customer wants the correlation of the HEO/VEO number to the actual eye opening at the input of the EOM in ps/mV? 

Both HEO and VEO go through 64 steps. So the horizontal eye opening in UI is HEO/64 and in ps it is (HEO/64)*(1/data rate)
The vertical eye opening is also divided into 64 steps. Each step has a different value depending on the eom_vrange setting and this has been scalled to the Vrange settings 0(3.125mV).  so to get the actual mV opening, you would multiply VEO by 3.125mV (the range0 resolution)

Regards,,nasser

Hi nasser-san

Thank you for the Answer.

But,Sorry , My writing seems to have been bad.

I want to confirm how to set rejister value.
Please let me how to diside these rejister value.

0x32　heo_int_thresh[3:0]
　　　　veo_int_thresh[3:0]

0x33　heo_thresh[3:0]
　　　　veo_thresh[3:0]

0x6A　veo_lck_thrsh[3:0]
　　　　heo_lck_thrsh[3:0]

Ex:heo_int_thresh[3:0] 0x1 ⇒ ? mV
　 　veo_int_thresh[3:0] 0x1 ⇒ ? UI or ? ps

Is there math formula ?

Best Regards,

Sugiyama

Sugiyama-San,

For registers 0x32 and 0x6a, you take the 4 bits value and shift left twice. Then this gets compared to the content of register 0x27 or 0x28. For example, if you set register 0x32[7:4] = 0x08. Then we left shift twice and this becomes 0x20. This 0x20 is compared against HEO reading from register 0x27 to decide whether to cause interrupt or not. Please note 0x20 is equivalent to 32 decimal or 32/63 or about 0.5UI. This means at 0.5UI the interrupt is caused(please note this is just an example). The same is true for VEO reading as well but the scaling is 3.25mV per step for the vertical eye opening.

For register 0x33, the customer is not expected to change this default settings. So please do not change this register content.

Regards,,nasser

I've understood how to translate HEO/VEO to real time/voltage value as below, from the following thread.

   HEO[UI] = (HEO in decimal) / 64
   VEO[V] = {(EOM Range Setting) / 64} * (VEO in decimal)

http://e2e.ti.com/support/interface/high_speed_interface/f/138/p/274653/977588.aspx#977588

I am understanding the above equation can be used to HEO and VEO translation to [UI] or [V]. What is different is that 4bit HEO/VEO data must shift 2 bits to the left and treat as 6bit data.

Now, I have one question. For VEO, is "EOM Range Setting" is in the equation. At default setting, EOM Voltage Range is set to +/-100mV. Does this mean that CDR state machine can only check the eye opening in this +/-100mV range ?

i.e. Even if you don't monitor Eye pattern through faset EOM function, do you need to change the EOM voltage range?

Best Regards,
Kawai

Kawai-San,

You are correct. When the default setting is +/-100mV or 200mV peak to peak the device per step setting is 200mV/64 = 3.125mV. Normally, there is FR4 PCB material and there is much more eye closure so +/-100mV Vrange setting is fine for customer design environment. Now if the eye is completely open, for example very clean signal, then using Vrange settings of +/-100mV shows the eye as completely open. In this case, we should use +/-400mV so you can monitor the complete eye diagram.

Regards,,nasser 

Nasser-san,

Thank you.

I understood as that Vrange setting may effect EQ/DFE adaptation optimization.

Generally, device have no problem with +/- 100mV setting. 

Best Regards,
Kawai