I.MX6Q 从EMMC启动 随机无法启动的问题？

[bruceli]

正常的板子启动 EMMC CLK 为374KHz, 然后切换到20M，50MHz。 无法启动的板子，EMMC CLK 起初为374KHz,后面切换到10M，16M，无法起来。（参看附件的波形）目前通过调试Core 供电电压1.33V和1.38V，没有变化。上电时序是VDD_HIGH_IN=VDD_SNVS_IN，3V3_HIGH_IN > 1.35V , 1.5V> 3.3V . 3V3上电后Delay 500ms POR_RST解复位。从现象上看，启动的内部ROM的状态机没有走到EMMC模式，这些都是BOOT_CFG配置的，如何解决这个问题，请大神帮忙看看，多谢？

[igorpadykov]

Hi Bruce

random eMMC boot failures may be caused by signal integrity issues

(noise signals) please check board layout against recommendations in

sect. 3.5.8 High speed signal routing recommendations i.MX6 System Development User’s Guide

and observing signals shape with oscilloscope.

http://cache.freescale.com/files/32bit/doc/user_guide/IMX6DQ6SDLHDG.pdf

I.MX6Q eMMC drive strength can be tweaked using BOOT_CFG2[0] (Use PAD_SETTINGS values)

please check Table 8-14, Table 5-7. i.MX6DQ Reference Manual

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf

Best regards
igor
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[bruceli]

Hi igor,

Thanks a lot for your suggestions. Just I retry to set Boot_CFG2[0] = 1 . But the board couldn't bring up anymore. I think it should be modify after boot up .  It is very difficult to solve. I have no good idea to check. 

[bruceli]

I.MX6Q 用SD4 接口连接Micron EMMC。哪位大神帮我看看，这是什么问题？