Article ID: 000076144 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Are there any issues with ZQ calibration in DDR3 SDRAM interfaces with multiple Chip Selects?

Environment

BUILT IN - ARTICLE INTRO SECOND COMPONENT
Description

Yes, the ALTMEMPHY megafunction does not correctly support periodic ZQCS (zq calibration short) commands for multiple ranks where any of the ranks are arranged such that they share the ZQ resistor. To fix this issue one is required to do the following steps:

1. Open the <variation_name>[_phy]_alt_mem_phy_seq.vhd file

2. Search for the "ZQCS" function and find it's use within state s_zq_cal_short (this is within entity <variation name>_alt_mem_phy_admin)

3. Change the "2**MEM_IF_NUM_RANKS - 1" ("2**MEM_IF_CS_WIDTH - 1" for levelled PHY) operand to the function to the operand "2**current_cs"

4. Save the file and if you require to simulate this change in a "verilog only" simulation setup then re-simgen the PHY as described in the External Memory PHY Interface Megafunction (ALTMEMPHY) userguide (PDF).

The above solution applies to both the levelling and non-levelling enabled PHYs. This issue will be fixed in a future version of Quartus® II software.

Related Products

This article applies to 5 products

Stratix® III FPGAs
Stratix® IV GT FPGA
Stratix® IV GX FPGA
Arria® II GX FPGA
Stratix® IV E FPGA

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