Curious, when discussing SD here, are we including SDHC?  And would an=20
SDHC card always be able to operate in a device setup for a regular SD=20
card?  I would think so, but found references that suggest otherwise=20
based on differences between the SD 1.0/1.1 spec and SD 2.0 spec.

Cheers,
-Neil.


On 6/17/2012 9:12 PM, IVP wrote:
>> I, IIRC, have seen about 400 kbytes/sec and others have verified
>> this number. Still, it's much above your 1 kbit/sec figure
> I use SD cards for dsPIC .wav storage and find even retrieval with
> SPI has a disappointingly low ceiling
>
> Reading one file of  44100Hz, 16-bit stereo (176.4 kbytes/sec) is
> OK but when trying to read much faster reliably you run into latency
> problems in the card controller, as Martin says. SPI is not the native
> comms for an SD card and presumably the card controller just can't
> keep up translating SPI to its 4-bit parallel O/S. In bursts you can
> read up to 350-400 kbytes/sec but it's not sustainable, unlike the
> transfers seen between say PC and card via a proper reader/writer
> which uses 4-bit parallel

--=20
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