Changes between Version 1 and Version 2 of MMC
- Timestamp:
- 12/01/2017 04:13:25 PM (7 years ago)
Legend:
- Unmodified
- Added
- Removed
- Modified
-
MMC
v1 v2 1 1 [[PageOutline]] 2 2 3 = MultiMediaCard (MMC) =4 A 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.3 = !MultiMediaCard (MMC) = 4 A !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. 5 5 6 7 [=#microsd] 6 8 == microSD == 7 Gateworks supports microSD (aka uSD) cards on several boards in the Laguna and Ventana product family. A microSD card typically operates at 3.3V (with 3.3V or 1.8V I/O) and uses 4bit I/O.9 Gateworks supports microSD (aka uSD) cards on several boards in the Newport, Ventana, and Laguna product families. A microSD card operates at 3.3V (with 3.3V or 1.8V I/O if the board allows it) and uses 4bit I/O. 8 10 9 11 References: … … 12 14 * https://www.sdcard.org/developers/overview/speed_class/ 13 15 16 17 [=#performance] 14 18 == Data Rates == 15 19 The !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. … … 42 46 * http://en.wikipedia.org/wiki/Secure_Digital#Ultra_High_Speed_bus 43 47 48 49 [=#newport] 50 == Newport == 51 The OCTEON TX CN80XX / CN81XX SoC has a single MMC host controller supporting 3 CMD signals which allows up to three devices to share the bus. Some Newport products support a combination of microSD and on-board eMMC. The MMC host controller supports: 52 * 1, 4, 8-bit data bus (8-bit used for eMMC, 4-bit used for microSD) 53 * transfer rates up to 52MHz 54 * single-data rate (SDR) and dual-data rate (DDR) 55 * DMA read/write on 512byte blocks 56 * stream mode is not supported but multiblock read/write operations are supported 57 * SPI mode not supported 58 * BOOT ROM supports booting from MMC 59 60 Newport boards supporting microSD have a connector that supports both SIM and microSD in one. 61 62 [=#ventana] 44 63 == Ventana == 64 Ventana boards supporting microSD have a connector that supports both SIM and microSD in one. The microSD card offers the following support: Fully compliant with SD command/response sets and Physical Layer as defined in the SD Memory Card Specifications, v3.0 including high-capacity SDHC cards up to 32 GB and SDXC cards up to 2TB. 65 45 66 The Freescale IMX6 SoC used on Ventana has an SD host controller that supports up to a 208MHz clock necessary for UHS-I SDR104 however this requires a microSD I/O voltage rail that is switchable between 1.8V and 3.3V which is available only on select Ventana board models (see below). If UHS-I clocking is not available a UHS-I card will be used in HS mode with a 50MHz clock resulting in a '''theoretical maximum I/O rate of 25MB/sec'''. '''Actual raw device throughput (using dd commands) has shown 19.5MB/sec''' for cards that advertise greater than 20MB I/O when operating in HS mode. 46 67 … … 59 80 60 81 82 [=#laguna] 61 83 == Laguna == 62 84 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'''.
