AF512UDI datasheet(73/91 Pages) ETC1

73 / 91 page

Revision 3.3

ATP Industrial Grade microSD Card Specification

with this condition, sending incompatible cards into the Inactive State. During the initialization

procedure, the host is not allowed to change the operating voltage range.

After the bus is activated the host starts card initialization and identification process (See Figure 6-28).

The initialization process starts with SD_SEND_OP_COND (ACMD41) by setting its operational

conditions and the HCS bit in the OCR. The HCS (Host Capacity Support) bit set to 1 indicates that the

host supports High Capacity SD Memory card. The HCS (Host Capacity Support) bit set to 0 indicates

that the host does not support High Capacity SD Memory card.

Receiving of CMD8 expands the ACMD41 function; HCS in the argument and CCS (Card Capacity

Status) in the response. HCS is ignored by cards, which didn’t respond to CMD8. However the host

should set HCS to 0 if the card returns no response to CMD8. Standard Capacity SD Memory Card

ignores HCS. If HCS is set to 0, High Capacity SD Memory Card never return ready statue (keep busy

bit to 0). The busy bit in the OCR is used by the card to inform the host that initialization of ACMD41

completed. Setting the busy bit to 0 indicates that the card is still initializing. Setting the busy bit to 1

indicates completion of initialization. The host repeatedly issues ACMD41 until the busy bit is set to 1.

The card checks the operational conditions and the HCS bit in the OCR only at the first ACMD41.

While

repeating ACMD41, the host shall not issue another command except CMD0.

If the card responds to CMD8, the response of ACMD41 includes the CCS field information. CCS is

valid when the card returns ready (the busy bit is set to 1). CCS=1 means that the card is a High

Capacity SD Memory Card.

CCS=0 means that the card is a Standard Capacity SD Memory Card.

The host performs the same initialization sequence to all of the new cards in the system. Incompatible

cards are sent into Inactive State. The host then issues the command ALL_SEND_CID (CMD2), to

each

card to get its unique card identification (CID) number. Card that is unidentified (i.e. which is in Ready

State) sends its CID number as the response (on the CMD line). After the CID was sent by the card it

goes into Identification State. Thereafter, the host issues CMD3 (SEND_RELATIVE_ADDR) asks the