Rockchip DDR DQ Eye Tool Guide

ID: RK-YH-YF-167

Release Version: V1.0.0

Date: 2021-03-05

Security Level: □Top-Secret □Secret □Internal ■Public

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Preface

Overview

The Rockchip DDR DQ Eye Tool provides the ability to view read/write eye diagrams for each DQ by entering commands under U-Boot.

Product Versions

Chip Name	Software Version
RV1126	U-Boot 2017.09
RK356x	U-Boot 2017.09

Intended Audience

This document (this guide) is primarily intended for the following engineers:

Hardware Engineers

Technical Support Engineers

Software Development Engineers

Revision History

Version	Author	Date	Description
V1.0.0	Yao Xuwei	2021-03-05	Initial version

Table of Contents

[TOC]

Usage

Preparation

Before building the U-Boot project, open menuconfig in the project root directory, go to Command line interface, configure Enable ddr test tool and save the build configuration (the Rockchip DDR DQ Eye Tool is integrated in the DDR Test Tool).
Build the U-Boot project and flash the Loader and uboot (refer to the "Build and Flash" related chapters in the UBOOT documentation).
Flash the Loader and uboot that support the DDR DQ Eye Tool (for RV1126 platform, you can flash the Loader packaged by the U-Boot project; for RK356x platform, please flash the Loader provided by Rockchip that supports this feature).
Connect the serial port of the board under test to the host PC, ensuring normal serial communication between the board and the host. When the board boots, the host should hold Ctrl + C to stop the board at U-Boot (the appearance of "<INTERRUPT>" indicates the board has stopped at U-Boot).

Viewing DDR DQ Read/Write Eye Diagram Under U-Boot

Enter the command under U-Boot:

ddr_dq_eye <DDR frequency in MHz>

The parameter <DDR frequency in MHz> specifies the DDR clock frequency for which to view the DQ eye diagram, in MHz. When left blank, the default is the maximum frequency.

Example: To view the DQ eye diagram at DDR clock frequency of 1056MHz, enter the command under U-Boot:
```
ddr_dq_eye 1056
```
Example: To view the DQ eye diagram at the maximum DDR clock frequency, enter the command under U-Boot:
```
ddr_dq_eye
```

Output Result Analysis

ddr_dq_eye_read

ddr_dq_eye_write

The tool first outputs tool version, DDR type, frequency, and other information.
The tool outputs read eye diagrams and write eye diagrams for each CS separately.
In the eye diagram output, positions marked with "-" are outside the eye, positions marked with "*" are inside the eye, and positions marked with "|" are sampling points.
The right side of the eye diagram shows the margins from the sampling point to the left and right boundaries of the eye (Margin_L, Margin_R), the sampling point position (Sample), eye width (Width), and other information. Eye widths marked in square brackets do not meet the minimum eye width limit (as shown for read eye diagram DQ0 in the figure).
The tool finally outputs the minimum eye width for both read and write eye diagrams, along with the minimum eye width limit value (selecting the closest frequency).

DDR DQ Minimum Eye Width Limits

Based on DEMO testing and relevant project experience, this document sets corresponding limits for the minimum read/write eye width of DDR DQ. If the minimum read/write eye width does not meet this limit, DDR operation may be unstable.

Meeting the DDR DQ minimum eye width limit only indicates that the DDR DQ eye width is relatively reliable under the current design. It does not mean that the DDR-related design definitely has no other issues. Please conduct further reliability testing according to actual usage requirements.

RV1126 DDR DQ Minimum Eye Width Limit Values

DDR Type	DDR Clock Frequency	Min Read Eye Width Limit	Min Write Eye Width Limit
LPDDR4	1056MHz	12	13
LPDDR4	924MHz	15	15
DDR4	1056MHz	13	9
DDR4	924MHz	15	11
LPDDR3	1056MHz	15	13
LPDDR3	924MHz	16	15
DDR3	1056MHz	14	14
DDR3	924MHz	17	17

RK356x DDR DQ Minimum Eye Width Limit Values

DDR Type	DDR Clock Frequency	Min Read Eye Width Limit	Min Write Eye Width Limit
LPDDR4	1560MHz	25	24
LPDDR4	1184MHz	30	29
DDR4	1560MHz	30	22
DDR4	1184MHz	32	26
LPDDR3	1184MHz	34	25
LPDDR3	1056MHz	39	28
DDR3	1184MHz	32	31
DDR3	1056MHz	39	34

Usage​

Preparation​

Viewing DDR DQ Read/Write Eye Diagram Under U-Boot​

Output Result Analysis​

DDR DQ Minimum Eye Width Limits​

RV1126 DDR DQ Minimum Eye Width Limit Values​

RK356x DDR DQ Minimum Eye Width Limit Values​