AF512UDI datasheet(85/91 Pages) ETC1

85 / 91 page

Revision 3.3

ATP Industrial Grade microSD Card Specification

card assumes the voltage specified in VHS as the current supplied voltage. Only 1-bit of VHS shall be

set to 1 at any given time. Check pattern is used for the host to check validity of communication

between the host and the card. If the card indicates an illegal command, the card is legacy and does not

support CMD8. If the card supports CMD8 and can operate on the supplied voltage, the response

echoes back the supply voltage and the check pattern that were set in the command argument. If VCA

in the response is set to 0, the card cannot operate on the supplied voltage. If check pattern is not

matched, CMD8 communication is not valid. In this case, it is recommended to retry CMD8 sequence.

Figure 7-3: SPI Mode Initialization Flow

READ_OCR (CMD58) is designed to provide SD Memory Card hosts with a mechanism to identify

cards that do not match the VDD range desired by the host. If the host does not accept voltage range, it

shall not proceed further initialization sequence. The levels in the OCR register shall be defined

accordingly. SD_SEND_OP_COND (ACMD41) is used to start initialization and to check if the card

has completed initialization. It is mandatory to issue CMD8 prior to the first ACMD41. Receiving of

CMD8 expands the CMD58 and ACMD41 function; HCS (High Capacity Support) in the argument of

ACMD41 and CCS (Card Capacity Status) in the response of CMD58. HCS is ignored by the card,

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