ALFAT-OM-337 GHI Electronics, ALFAT-OM-337 Datasheet - Page 48

• Manufacturer Part Number: ALFAT-OM-337
• Description: Memory IC Development Tools ALFAT USB / SD to UART / SPI OEM BOARD
• Manufacturer: GHI Electronics

Specifications of ALFAT-OM-337

• Rohs: yes
• Product: SD OEM Board
• Tool Is For Evaluation Of: SD, SDHC, MMC Cards, USB drives
• Memory Type: Flash
• Operating Supply Voltage: 3.3 V
• Description/function: OEM board offers a seamless way to access files on SD & MMC cards and on USB memory drives
• Interface Type: I2C, SPI, UART, USB
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Part # Aliases: GHI-ALFAT-OM-337

9. Conditions of Use and Performance
Current storage media market is flooded with low grade devices. These devices may work
on a PC but that doesn't mean the device was tested to follow the standards. Also, other
devices may have advanced features not suitable for embedded devices. For example,
some USB memory drives have a built in USB hub. We made our best to support a wide
range of storage medias that follow the standards. But GHI Electronics does not guarantee
that ALFAT will be able to access all storage media, especial if it one of the medias
mentioned earlier.
For products that integrates ALFAT SoC process, it is important to test different media
devices and offer a range of tested devices to end user. GHI Electronics doesn't
recommend any specific brand but always recommends selecting a well known source. If
media is not supported, a failure happens at initialization, not at file read and write usually.
If a media mounts with no errors, in most cases, it is safe to assume it will function with no
later issues.
As discussed in the integration section, power source is a big source of problems as well.
ALFAT is capable of running at lower voltage or somewhat noisy voltage source. On the
other hand, the media may or may not work with bad voltages. Make sure the voltage
source to the media is reliable and there is large enough capacitor as close as possible to
the media connector. We recommend adding 0.1uF and 22uF.
There are many factors that affects the file access speed. Some storage media devices
have internal buffering, others have high speed rating. But even on the exact same media,
speeds might differ between different tests. Here are some factors that affect the speed on
the same media: fragmentation, media life and voltage.
Fragmented storage runs slower because the system needs to spend more time, or even
read more sectors from the FAT table, to find the needed cluster. Formatting the media
should take care of this fragmentation.
Also, storage access speed decreases when the storage get closer to the end of life. The
time needed to erase sectors increases while the device is maturing. Some sectors may
even start failing at some point which causes more delays.
Finally, while some devices can run on a range of voltages, the lower the voltage the
slower the device usually runs. Noisy power source may cause errors while accessing the
media that slows the speed down.
9.1. Selecting the Right Storage Media
9.2. File Access Speed
GHI Electronics
Rev. 1.13
Page 48 of 51
Conditions of Use and Performance
ALFAT SoC Processor
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