136 bits length
0
0
1
CRC
Content
48 bits length
0
0
1
CRC
Content
48 bits length
0
1
1
CRC
Content
Functional Description
18.3.1.2.2 Data Format
Coding Scheme for Command Token
Command packets always start with 0 and end with 1. The second bit is a transmitter bit1 for a host
command. The content is the command index (coded by 6 bits) and an argument (for example, an
address), coded by 32 bits. The content is protected by 7-bit CRC checksum (see
).
Figure 18-10. Command Token Format
Coding Scheme for Response Token
Response packets always start with 0 and end with a 1. The second bit is a transmitter bit0 for a card
response. The content is different for each type of response (R1, R2, R3, R4, R5, and R6) and the content
is protected by 7-bit CRC checksum. Depending on the type of commands sent to the card, the SD_CMD
register must be configured differently to avoid false CRC or index errors to be flagged on command
response (see
). For more details about response types, see the Multimedia Card System
Specification, the SD Memory Card Specification, or the SDIO Card Specification.
Table 18-8. Response Type Summary
(1)
Response Type
Index Check Enable
CRC Check Enable
SD_CMD[17:16]
SD_CMD[20]
SD_CMD[19]
RSP_TYPE
CICE
CCCE
Name of Response Type
00
0
0
No Response
01
0
1
R2
10
0
0
R3 (R4 for SD cards)
10
1
1
R1, R6, R5 (R7 for SD cards)
11
1
1
R1b, R5b
(1)
The MMC/SD/SDIO host controller assumes that both clocks may be switched off, whatever the value set in the
SD_SYSCONFIG[9:8] CLOCKACTIVITY bit.
and
depict the 48-bit and 136-bit response packets.
Figure 18-11. 48-Bit Response Packet (R1, R3, R4, R5, R6)
Figure 18-12. 136-Bit Response Packet (R2)
3355
SPRUH73H – October 2011 – Revised April 2013
Multimedia Card (MMC)
Copyright © 2011–2013, Texas Instruments Incorporated