AnsweredAssumed Answered

How to power cycle SD card?

Question asked by Zaid Albassam on Mar 29, 2017
Latest reply on Apr 12, 2017 by Pavel Chubakov



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 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."