Max seep of the SD slot?

Andy Green andy at openmoko.com
Thu Jul 24 08:49:26 CEST 2008


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Somebody in the thread at some point said:

| | access let me know what the max speed of the Glamo's MicroSD card
| | controller is?  looking for MB/s, or something like that.
|
| It's just slightly under 25MHz SD Clock, we round it up and call it 25MHz.

| What is that in MB/s?

Well, a good rule of thumb for generic 1-bit transfer is divide by 10
for the max speed in Bytes/sec you could expect, here we have 4-bit so
the peak raw trasfer speed is ~10MBytes/sec *BUT* after Glamo pulls the
data from the card, we have to sit there dragging it into the CPU
memory, on top of card latencies and command setup the speed is way
slower, still a decent ~2MBytes/sec each way IIRC.

- -Andy
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