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DDR时钟



      我们用贵公司的DM8168自制了一块板子,现在用SD卡启动不起来,上电时序、时钟、启动模式设置都没问题,可是板子boot不起来,测得ddr的差分时钟是800M,但幅度只有49mv(如图),请问这种时钟信号能够让DDR工作起来吗?谢谢指导~

  • 挂载CCS看一下?

    DDR的其他信号呢?你应该用了2组DDR控制器吧,另外一组也是这样吗

    做了几块板子,都是一样现象?

  •   从波形上看你的DDR时钟的幅值不够,请问你使用的多少带宽的示波器以及探头。由于你的DDR主频已经到了800M, 建议使用2G以上带带宽的示波器探头。另外你能够使用CCS连上你的板子么?如果不行,怀疑是硬件问题,如果CCS可以连接,请参考processors.wiki.ti.com/index.php/DM816x_C6A816x_AM389x_DDR3_Init,把DDR这部分的参数配置一下。

    Regards,

    Louis

  • Louis:

          您好!谢谢您给我的建议!我换了一个1.5G 的探头,测了一下差分时钟是800M,幅度是200mv,波形规整,如下,麻烦您看一下这样的差分时钟能达到标准吗?

    我也按照您的建议连了一下CCS,test connection 的结果如下:

    会提示“target power loss”错误。launch the dm8168 以后会出现下面的情况:

    这样的情况,能说明ccs能够连接吗?期待您的回复,谢谢! 

  •   从波形截图上看,看不出CLK信号有什么问题。 另外DDR时钟查分信号上的终端匹配电阻是多大的?是否满足DATASHEET的要求?尝试把这那两个匹配电阻去掉看是否有改善。 另外,你的仿真器连接其他的板子是OK的么?请先确认仿真器是否工作正常。具体步骤可以看一下:http://processors.wiki.ti.com/index.php/DM816x_AM389x_PSP_Flashing_Tools_Guide

    Starting CCS
    • System Requirements – CCS version 5.1.0.05000 installed on Windows XP
    • Make sure the Boot Mode / Configuration Select Switch is set for the respective boot mode
    • Connect the XDS560 emulator to the EVM
    • Start CCSv5 by navigating to 'Start' menu in Windows XP
    • Use target configuration file  tools/DM816x.ccxml. If there is a need to create a new configuration, then follow
    steps below:
    • Select "View -> Target Configurations"
    • In the "Target Configurations" tab select "New Target Configuration File" button (in the top left corner)
    • Name the file (eg. ti816x_usb.ccxml)
    • Connection = Spectrum Digital TI XDS560V2 STM USB Emulator
    • Board or Device = TI816x | TI814x |TI813x * select the connected device from the list
    • Save configuration
    • From next run, the project and target configuration will be readily available and can be skipped
    • Select "Debug Perspective" in CCS if not there already: "Window -> Open Perspective -> Debug"
    • Select "View" -> "Target Configurations"
    • Expand "User Defined" configuration tree, Right click on the newly created target configuration and select
    "Launch Selected Configuration"
    TI81XX PSP Flashing Tools Guide 2
    • This should launch debug session
    • In Debug view, (scroll till the end) Select "Spectrum Digital TI XDS560V2 STM USB Emulator_0/Cortex
    A8" connection.
    • Right click on the Cortex A8 core listed and click on "Connect Target"
    • A "Dissassembly" view with PC halted should pop up in one of the tabs. If not, do a 'System Reset' from Target
    menu and then Halt (for GP device)

    Regards,

    Louis

  • Louis:

           您好!差分线上的匹配电阻已经去掉,对时钟信号的幅度有一定改善(现在是0.25V)。按照您的建议,我用仿真器(我用的是Blackhawk USB560-M Emulator)连了一下6670开发板,结果OK,说明仿真器没问题。连上仿真器,不管我对板子加电与否,test connection 的结果都是"The controller has dected a target power loss" ,如图:

    进入Debug界面,右键点击“ the Cortex A8 core”,然后点击"Connect Target",显示结果如下 请问可能是什么原因导致连不上CCS,该怎么解决,请赐教,谢谢!