local_reset_done and emif_usr_reset_n on emif ip

[CosmoKramer]

Could someone please help me understand difference and relation between these two signals on the emif ip - local_reset_done and emif_usr_reset_n ?

If I toggle local_reset_req to the ip, then local_reset_done will go low indicating that the ip is in reset. at some point it will go high indicating that it is out of reset. 

 what happens to emif_usr_reset_n after i toggle local_reset_req ?

which one of the two signals will go high first? 

I have a design where emif_usr_reset_n is high but local_reset_done is still low.

Assuming that a high on  emif_usr_reset_n means that the ip is out of reset, should not local_reset_done be high before or at least at same time that  emif_usr_reset_n is high?

I looked at the user guide but it does not have much in terms of details. 

[AdzimZM_Intel]

Hi,

local_reset_req (input)

local_reset_done (output)

local_reset_req has effect only when local_reset_done is high.

The local_reset_done signal transitions high once the calibration is completed.

Once the reset is requested (local_reset_req = high, for at least 2 EMIF core clock cycles), the EMIF interface will enter reset sequence (local_reset_done = low).

Then the core reset signal (emif_usr_reset_n) is driven low. The emif_usr_reset_n is active low signal.

After the reset sequence is done, local_reset_done is driven high again.

Regards,

Adzim

[CosmoKramer]

Thank you for replying. But my question was which one of the two - emif_usr_reset_n, local_reset_done - goes high first?

or do they go high at same time?

[AdzimZM_Intel]

Hi,

emif_usr_reset_n is an active low signal.

It's asserting when entering reset sequence then perform calibration.

local_reset_done is a active high signal.

It's asserting when the calibration is done.

According to the initialization flow, the memory will run a calibration first before it's able to accept command from user logic.

Therefore, the emif_usr_reset_n should be trigger first.

Regards,

Adzim

[CosmoKramer]

Just to make sure i understand it correctly, please confirm:

1) after user issues reset_request, which of the two signals go high first:

emif_usr_reset_n 

local_reset_done 

2) When these signals go low to high, it means that IP is out of reset. is that right?

thank you. 

[AdzimZM_Intel]

Hi,

"1) after user issues reset_request, which of the two signals go high first:

emif_usr_reset_n 

local_reset_done "

• The local_reset_done should go from high to low. (active high)
• Then emif_usr_reset_n should go from high to low. (active low)
• The emif_usr_reset_n will go high again based on the calibration sequence.
• Then after the calibration is finished, the local_reset_done will go high again.

"2) When these signals go low to high, it means that IP is out of reset. is that right?"

• Yes.

Regards,

Adzim