SCSI to IDE
cclist at sydex.com
Sat Dec 4 16:56:21 CST 2010
On 4 Dec 2010 at 18:50, Alexandre Souza - Listas wrote:
> Speed Class Rating
> The Speed Class Rating is the official unit of speed measurement for
> SD Cards, defined by the SD Association. The Class number represents a
> multiple of 8 Mb/s (1 MB/s), and meets the least sustained write
> speeds for a card in a fragmented state.
Using SPI, 400KB/sec is about the top rate for read, 200KB/sec for
write. If you can get 1MB/sec write speed, more power to you. Most
uC implementations get substantially less.
Most first-timers trying to wring performance using SPI out of an
SDHC are surprised by the low transfer rate.
Cache-ing would help a lot.
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