External Memory Interfaces Intel® Stratix® 10 FPGA IP User Guide

ID 683741
Date 9/26/2022
Public

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Document Table of Contents

3.6. User-requested Reset in Intel® Stratix® 10 EMIF IP

The following table summarizes information about the user-requested reset mechanism in the Intel® Stratix® 10 EMIF IP.
Table 9.  
  Description
Reset-related signals

local_reset_req (input)

local_reset_done (output)

When can user logic request a reset?

local_reset_req has effect only when local_reset_done is high.

After device power-on, the local_reset_done signal transitions high after the completion of the first calibration, whether the calibration is successful or not. In subsequent calibration in user mode, the local_reset_done signal transitions high once the calibration is completed. The local_reset_done signal takes more time to transition high in first calibration after device power-on as more operations are required put the PHY into working state.

Is user-requested reset a requirement?

A user-requested reset is optional. The I/O SSM automatically ensures that the memory interface begins from a known state as part of the device power-on sequence. A user-requested reset is necessarily only if the user logic must explicitly reset a memory interface after the device power-on sequence.

When does a user-requested reset actually happen?

A reset request is handled by the I/O SSM. If the I/O SSM receives a reset request from multiple interfaces within the same I/O column, it must serialize the reset sequence of the individual interfaces. You should not make assumptions about when the reset sequence will begin after a request is issued.

Timing requirement and triggering mechanism.

Reset request is sent by transitioning the local_reset_req signal from low to high, then keeping the signal at the high state for a minimum of 2 EMIF core clock cycles, then transitioning the signal from high to low. local_reset_req is asynchronous in that there is no setup/hold timing to meet, but it must meet the minimum pulse width requirement of 2 EMIF core clock cycles.

How long can an external memory interface be kept in reset?

It is not possible to keep an external memory interface in reset indefinitely. Asserting local_reset_req high continuously has no effect as a reset request is completed by a full 0->1->0 pulse.

Delaying initial calibration.

Initial calibration cannot be skipped. The local_reset_done signal is driven high only after initial calibration has completed.

Reset scope (within an external memory interface).

Only circuits that are required to restore EMIF to power-up state are reset. Excluded from the reset sequence are the IOSSM, the IOPLL(s), the DLL(s), and the CPA.

Reset scope (within an I/O column).

local_reset_req is a per-interface reset.

Method for Initiating a User-requested Reset

Step 1 - Precondition

Before asserting local_reset_req, user logic must ensure that the local_reset_done signal is high.

As part of the device power-on sequence, the local_reset_done<