DS90UB948-Q1: 0x35 register

Hi Charley,

Still have below questions. 

1. 0x35[6] : Datasheet shows "Set high to restart AEQ adaptation from initial value. Method is write HIGH then write LOW - not self clearing."

a. If I write high in this bit and then AEQ value will renew every time when deserializer power on. Is it right?

b. If I  write HIGH then write LOW in this bit and then AEQ will remain value when deserializer was power on initially. Is it right?

c. Do you thingk that AEQ restart renew every time if generate extra EMI issue?

2. 0x35[5] and 0x35 [4] : Does it mean that if I use in long cable situations, these two bit should be high, is it right?

a. What is the "long" cable definition?

Thank you for your support.

Regards,

Roy

Hi Roy,

1. When the device power on, AEQ will be running automatically without setting the 0x35 register. The 0x35 register is used after device power on, by writting high then low to 0x35[6] to restart AEQ from the initial state.  AEQ restart is unlikely to generate extra EMI issue.

2. This is helpful for long cable situation because for long cables, higher AEQ values will likely work better so you can use register 0x35 and 0x45 to set the minimum AEQ level. 

In this case, you would set 0x35[5] and 0x35[4] to high and set the min/max AEQ value in 0x45. 

"long" cable actually depends on the cable quality. Rather then use a set length, it is better to use the MAP tool included in our ALP software to check the channel quality and then determine if you should use the register 0x35[4] or not.

Best Regards,

Charley Cai

Hi Charley,

I'm not sure the  "The 0x35 register is used after device power on, by writting high then low to 0x35[6] to restart AEQ from the initial state."

Could you help clarify below 0x35[6] setting?

1. What is the difference in below setting

a. 0x35[6] by writing high after device power on

b. 0x35[6] by writing high then low to 0x35[6] after device power on

Regards,

Roy

Hi Roy,

Register 0x35[6] is not self-clearing. So if you write a high to 0x35[6], then AEQ will be stuck at reset state. 

By writing high and then low to 0x35[6], you will put AEQ to reset and then release it from reset so AEQ can start adapting. 

Best Regards,

Charley Cai

Hi Charley,

So the suggestion for 0x35 setting is writing high and the low to 0x35[6]

The AEQ performance is better that default 0x35[6]=0 , is it right?

Regards,

Roy

Hi Roy,

Register 0x35[6] doesn't affect the performance. This bit is used for restarting the AEQ. 

AEQ will only adapt when 0x35[6]=0.

Best Regards,

Charley Cai

Hi Charley,

Thank you for your comments. 

1. If 0x35 setting is writing high and the low to 0x35[6] : Adaption will be restarted on both ports every when I power up the system?

2. If 0x35 setting is default value(0x35[6]=0) which means "I don't modify writing high and the low to 0x35[6]" How does Adaption do in this setting?

Regards,

Roy

Hi Charlie,

So AEQ will start automatically every time when power up the system. Why datasheet recommend write high and the low to 0x35[6] to let AEQ will restart and will restart on both port.

Is there any difference between blue and red action?

Regards,

Roy 

Hi Charlie,

Thank you for your detailed comments!

Question, "Once the deserializer is powered on, the AEQ is continually searching through EQ settings", What criteria does Deserializer use to find the EQ settings? 

Question, "Set high to restart AEQ adaptation from initial value", What is the meaning of initial value? (Table58)

Regards,

Roy

Hi Roy,

The Des will check for errors in the link. If at a particular EQ setting, error is detected, the AEQ will go to the next setting. 

The AEQ has a 15 stages, the initial value would just be the lowest stage of the AEQ.

Best Regards,

Charley Cai