Changes between Version 3 and Version 4 of MMC


Ignore:
Timestamp:
12/01/2017 05:21:41 PM (7 years ago)
Author:
Tim Harvey
Comment:

added capability table and more performance details

Legend:

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  • MMC

    v3 v4  
    44A !MultiMediaCard (MMC) is a memory card standard used for solid-state storage typically used in digital cameras, smart-phones, and portable media players. There are several form-factors of cards that fall under the specification. MMC cards use the SDIO data bus standard.
    55
     6The following Gateworks boards support MMC:
     7||= Family =||= Board =||= max clock =||= eMMC =||= microSD =||
     8|| Newport  || GW630x/GW640x  || 52MHz || 8GB bootable || SDHC/SDXC DS/HS bootable ||
     9|| ||
     10|| Ventana  || GW560x         || 208MHz || 8GB 52MHz bootable || SDHC/SDXC DS/HS/UHS-I bootable ||
     11||          || GW52xx/GW53xx/GW54xx/GW5530 || 208MHz ||  || SDHC/SDXC DS/HS/UHS-I^^^1^^^ bootable ||
     12|| ||
     13|| Laguna   || GW2388  || 50MHz || || SDHC DS/HS not bootable ||
     14 1. Earlier Ventana GW52xx/GW53xx/GW54xx board revisions did not support UHS-I - see [#ventana ventana below]
     15
     16Performance depends on various factors (see [#performance below] for more details)
    617
    718[=#emmc]
    … …  
    1223 * supports several hardware partitions
    1324 * 8-bit data bus
     25 * Dual-Data-Rate (DDR) (Note this is supported on microSD if the card/controller support UHS-I)
    1426 * device is on-board and thus non removable
    1527
    … …  
    137149
    138150[=#performance]
    139 == Data Rates ==
     151== Performance and Data Rates ==
     152Performance of MMC devices depend on the following factors:
     153 * max clock speed
     154 * mode: DS/HS/UHS-I
     155 * bus width: 4-bit for microSD, 8-bit for eMMC
     156 * cpu performance and DMA capabilities
     157
    140158The !SecureDigital (SD) card spec originally defines a speed classes rating to refer to the I/O speed capabilities of the specific card. The class is specified on the card with icons that are denoted in the SD card specification. The class specified the write speed (which was important for Digital cameras) but a shortcoming of this system is it did not specify read speed.
    141159
    … …  
    189207Ventana boards that are capable of UHS-I data rates:
    190208||= board model =||= revision =||
    191 || GW54xx        || E          ||
    192 || GW53xx        || E          ||
    193 || GW520x        || D          ||
    194 || GW522x        || B          ||
     209|| GW560x        || A+         ||
     210|| GW553x        || A+         ||
     211|| GW54xx        || E+         ||
     212|| GW53xx        || E+         ||
     213|| GW520x        || D+         ||
     214|| GW522x        || B+         ||
    195215* Standard board models at the revision above will have UHS-I capability loaded by default, however for specials (GW5xx-SPxxx) please contact sales@gateworks.com to inquire if UHS-I support is available.
    196216
    … …  
    203223[=#laguna]
    204224== Laguna ==
    205 The Cavium cns3xxx SoC used on Laguna has an SD host controller that supports a 50MHz max clock which results in a '''theoretical maximum I/O rate of 25MB/sec'''.
     225The Cavium cns3xxx SoC used on Laguna has an SD host controller that supports:
     226 * 50MHz clock
     227 * SD 2.0
     228 * MMC 4.2
     229
     230A 4-bit SDR microSD at 50MHz results in a max bus throughput of 25MB/sec (actual results are less as they depend on CPU performance)