Pullup resistors when interfacing an SD card to SPI?

Hi All,

I'm interfacing an SD card to a Cypress PSoC5 via SPI.  I originally
tried to get it to work with one of these adapters
http://ucontroller.com/documentation/SDCardDoc.html, but it didn't
work.  I did get it to work fine by hard wiring an SD card in without
the pullup resistors.

Can anyone tell me which pullup resistors are needed and why, as it
only seems to work without them.

TY,
Fred

fred wrote:
> Hi All,
> 
> I'm interfacing an SD card to a Cypress PSoC5 via SPI.  I originally
> tried to get it to work with one of these adapters
> http://ucontroller.com/documentation/SDCardDoc.html, but it didn't
> work.  I did get it to work fine by hard wiring an SD card in without
> the pullup resistors.
> 
> Can anyone tell me which pullup resistors are needed and why, as it
> only seems to work without them.
> 
> TY,
> Fred

Sounds like a timing issue. Lead length ?. Check the signal levels and
waveform timings with a scope. It's the only way to see what's really
happening.

If the spi is on a port line, also check things like output config
(totem pole ?) for the data and clock outputs etc...

Regards,

Chris