MPC8535 eSDHC Specific FAQs

Document created by Omar Cruz Employee on Jul 31, 2012Last modified by Omar Cruz Employee on Jul 31, 2012
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MPC8535 Hardware spec states that either SDHC_CD, or SDHC_DAT3 can be used for card detection. Do you have to set the bit PROCTL[D3CD] specifically, if you want to use the DAT[3] method? This, plus adding the pull-down?

PROCTL[D3CD] has to be set to 1 if DAT3 is used as card detection. A pull down is needed as well per spec. It should be an external pull down.

MPC8535 HW spec mentions that if SDHC_DAT[3] is not used, SDHC_CD must be used, but it can be implemented by GPIO. What does that mean? Does it mean external (non CPU) GPIO could trigger the SDHC_CD transition?

If DAT3 is not used as card detection pin, a separate pin has to be used. For 8535, SDHC_CD_B/GPIO[4] pin is used. PMUXCR[SDHC_CD] pin should set to 1. If PROCTL[D3CD] =0 & PMUXCR[SDHC_CD]=0, the PRSSTAT[CDPL] field is unaffected by the external card detect pin, and will permanently indicate that a card is present.