How to power cycle SD card?

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How to power cycle SD card?

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zalbassam
Contributor I

Hi,

I have a problem on the ls1012ardb sd card and need help.

If I use a UHS-I card on the LS1012ARDB and switch the ESDHC1 to SDR104 mode with 1.8V signalling, everything works fine. However after I restart the board (without removing the card from the slot), by writing RESET_REQ in the RSTCR register, and try to reinit the sd card, the sd card refuses to switch to the 1.8v signalling (ACMD41 returns with S18A=0). If i remove and reinsert the card, 1.8v signalling is accepted and SDR104 works. I tried to reset the eSDHC block, but didnt help.

My question, Is there a way to power cycle the sd card to work around the problem?

SD spec 4.01 in 4.2.3.1 states:

"UHS-I supported host sets S18R=1 in the argument of ACMD41 to request the card to switch 1.8V signaling level. UHS-I card respond with S18A=1 in the response of ACMD41 (if in 3.3V signaling
mode) and then host can issue voltage switch command. Once voltage switch is performed, UHS-I card
indicates S18A=0 to keep current signal voltage. In UHS-II mode, the card always indicates S18A=0."

Thanks,

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Pavel
NXP TechSupport
NXP TechSupport

Could you create service request about this problem? See the following page:

How I could create a Service Request? 

Add link to this Community (How to power cycle SD card?) in this service request.


Have a great day,
Pavel Chubakov

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Pavel
NXP TechSupport
NXP TechSupport

Do you use command sequence from the Section 3.9.4 of the SD spec 4.01?


Have a great day,
Pavel Chubakov

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zalbassam
Contributor I

Yes! and it works with:

- Cold restart (unplug and replug the power cable) while the card is in the slot.

- Removed and inserted the card.

That means the command sequence is correct. no?

It does NOT work when:

- The board is warm restarted (by writing RESET_REQ in the RSTCR register, or pressing the reset button) while the card is in slot.

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kamhabs
Contributor I

Actually I have the same question as Zaid as well.  Once the SD card is switched from 3.3V to 1.8V is there any way to switch it back?  For example ... if I want to operate at faster SD frequency I switch the card to 1.8V but let's say I want to go back to a slower frequency then how do I switch the card back to 3.3V ?

thx

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Pavel
NXP TechSupport
NXP TechSupport

It looks like that SD driver does not detect SD card after power up if SD card was connected before power up.

Look at description of the CINS bit in the LS1012a Reference Manual.


Have a great day,
Pavel Chubakov

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zalbassam
Contributor I

Hi Pavel,

Thanks for your answer. Your answer doesnt answer my question. As I described in the question, after a warm reset (with the card is plugged) the card does get detected, however the card has already switched to 1.8v signalling and only a power cycle to the card would get it back to the 3.3v signalling. This issue is blocking us from supporting UHS-I for the esdhc. So:

1. Is the UHS-I modes for the ESDHC supposed to be supported on the LS1012ARDB?

2. if the answer to 1 is yes, How to power cycle the sd card for the case described above?

Thanks again for your support.

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zalbassam
Contributor I

Iam still stuck on this one :smileysad: Any one please can help here?

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