14 Replies Latest reply on Jun 22, 2015 12:51 PM by gabriel.thomas

Bay Trail E3800 series and SDCARD UHS-I modes

B-O May 13, 2015 6:30 AM

Hi,

I'm currently working with the SD card interface on Bay Trail E3800 series. It looks like UHS-I modes are limited to SDR12, SDR25 and DDR50 modes. SDR50 and SDR104 doesn't seem to be supported according to the capability bits. As SDR104 are very similar to HS200 mode, I'm a bit surprised it's not supported. As SDR50 may require tuning and SDR104 requires tuning, that may be the reason why they are not supported.

Are there any differences depending on micro code revisions? Some never generations may support SDR50 and SDR104?

Coding are no problem as the host capability bits can be checked for support, but it would be nice to know if the fastest modes will be supported in the future.

Best regards,

B-O Bergman

Winzent Technologies

Re: Bay Trail E3800 series and SDCARD UHS-I modes

gabriel.thomas May 13, 2015 9:41 AM (in response to B-O)

Hello Berth,

Welcome back to the Intel Embedded Community.

We are going to review the SDR50 and SDR104 compatibility with the microcode.

Stay tuned!

Regards,

Gabriel Thomas
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- Re: Bay Trail E3800 series and SDCARD UHS-I modes
  
  B-O May 13, 2015 1:00 PM (in response to gabriel.thomas)
  
  Thank you!
  
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  - Re: Bay Trail E3800 series and SDCARD UHS-I modes
    
    gabriel.thomas May 13, 2015 1:59 PM (in response to B-O)
    
    Hello Berth,
    
    We suggest you to verify with your BIOS and Driver developers to check that your design has implemented the workaround of the erratum VLI55.
    You can find more information in the document #329901, Intel Atom Processor E3800 Product Family, Specification Update - public, page 31.
    
    I hope this information is useful,
    
    Best regards,
    Gabriel Thomas.
    
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    - Re: Bay Trail E3800 series and SDCARD UHS-I modes
      
      B-O May 14, 2015 12:24 AM (in response to gabriel.thomas)
      
      Hello Gabriel,
      
      VLI55 is an xHCI issue. You mean VLI53? In any case VLI53 is referring to DDR50. I know the controller support SDR12, SDR25 and DDR50. I would like to know if it supports SDR50 and SDR104 modes now or will support them in the future.
      
      I'm the BIOS developer and I'm currently implementing the SDCARD initialization. The code for SDR50 and SDR104 will not be needed if these modes never will be available. As our BIOS philosophy is to only implement code that are actually used, I want to know if these modes will be supported by the E3800 series chip, so the code that support them will be useful.
      
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      - Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        gabriel.thomas May 20, 2015 2:26 PM (in response to B-O)
        
        Hello Berth,
        
        We are sorry for the delay, we will get back to you soon with additional information.
        
        Regards,
        
        Gabriel Thomas
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        B-O May 22, 2015 12:25 AM (in response to gabriel.thomas)
        
        Hello Gabriel,
        
        I'm wondering if you have some schematics how Micro SD should be connected to Bay Trail to be able to use UHS-I modes (1.8V). I guess that the SD3_PWREN# and SD3_1P8EN needs to be connected to some power switch circuit, that output 3.3V if SD3_1P8EN is low and 1.8V if SD3_1P8EN if high. The output of the power circuit should be connected to the VDD of the Micro SD connector?
        
        I noticed that the SD3_PWREN# and SD3_1P8EN signals on Minnow board Max are test points and VDD on the Micro SD are connected to 3.3V. Thus the SDHCI power control register are useless and the SDHC/SDXC can only run in 3.3V modes (standard and high speed mode)? To my understanding the SDHCI power control register can be used to switch power on by an external regulator or directly control SOC power to be routed to the SC card VDD. Can you verify it works?
        
        I guess on a fully functional board you may have two options to support 1.8V UHS-I modes. One using the power control register, setting the power to 1.8V after SD card voltage switch. The other using the power on bit in the power control register to drive the SD3_PWREN# signal and the 1.8V enable in the host control register 2 to drive the SD3_1P8EN signal. These signals would then be connected to a power switching circuit driving the VDD input to the SD card.
        
        I hope you can help me sort this out!
        
        Best regards,
        
        B-O
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        gabriel.thomas May 22, 2015 1:15 PM (in response to B-O)
        
        Hello Berth,
        
        The SDR50 and SDR104 modes are supported by the Intel® Atom™ Processor E3800 processors, because they are part of the SD 3.0 specification, which is the supported by these devices. You can confirm this information in the document #538136, section 16, Intel(R) Atom(TM) Processor E3800 Product Family Datasheet .
        
        It is important to clarify that these modes are the bus speeds of the SD High Capacity (SDHC™) and SD Extended Capacity (SDXC™), specifically the Ultra High Speed Phase I (UHS-I) bus design variants. You can confirm this information as a reference at the following web site:
        
        https://www.sdcard.org/developers/overview/bus_speed/
        
        The UHS-I bus design for SDHC and SDXC cards was added in SD spec 3.0. You can confirm this information as a reference as well at:
        
        http://kb.sandisk.com/app/answers/detail/a_id/2520/~/sd%2Fsdhc%2Fsdxc-specifications-and-compatibility
        
        I hope this information is useful.
        
        Regards,
        
        Gabriel Thomas
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        gabriel.thomas May 22, 2015 1:13 PM (in response to gabriel.thomas)
        
        Hello Berth,
        
        Please check the section 13.2, from the document #512379, Intel(R) Atom(TM) Processor E3800 Product Family Platform Design Guide (PDG).
        
        Best regards,
        
        Gabriel Thomas.
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        B-O Jun 19, 2015 1:51 AM (in response to gabriel.thomas)
        
        Hi Gabriel,
        
        I wonder if this applies to the Bay Trail-T series as well, i.e. only SDR12, SDR25 and DDR50 UHS modes are supported? Are there any Bay Trail version supporting all UHS-I modes?
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        B-O May 23, 2015 6:17 AM (in response to gabriel.thomas)
        
        Hi Gabriel,
        
        Thank you for your help! I studied the suggested document (#538136) and SD/SDIO card does not support SDR50 and SDR104. It supports 3.3V standard mode and high speed mode, 1.8V (UHS-I) SDR12, SDR25 and DDR50.
        
        Minnowboard Max supports only 3.3V modes as they use fixed VDD at 3.3V. The UHS-I CMD11 (1.8V switch) command will execute, negate the DAT[3:0] lines, but never complete with the DAT[3:0] lines high. Thus the voltage switch sequence described in the standard will fail for UHS-I memory cards. So if anyone is wasting time trying to get UHS-I modes to work on Minnowboard Max, you can stop now.
        
        Best regards,
        
        B-O
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        gabriel.thomas Jun 19, 2015 11:37 AM (in response to B-O)
        
        Hello Berth,
        
        Thank you very much for the great information. It is very useful.
        
        Regards,
        
        Gabriel Thomas.
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        B-O Jun 20, 2015 2:05 PM (in response to gabriel.thomas)
        
        Thank you Gabriel!
        
        I will continue to share information in hope it will be helpful for anyone.
        
        B-O
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        B-O Jun 20, 2015 2:14 PM (in response to gabriel.thomas)
        
        I'm currently adopting our BIOS to a platform based on Bay Trail-T Z3745. It has eMMC and Micro SD card, so I will soon know the modes supported for the T version of Bay Trail.
        
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        Re: Bay Trail E3800 series and SDCARD UHS-I modes
        
        gabriel.thomas Jun 22, 2015 12:51 PM (in response to B-O)
        
        Hello Berth,
        
        Great!, This information will be very helpful for sure.
        Thanks for your valuable efforts.
        
        Regards,
        
        Gabriel Thomas.
        
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