SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
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 13-178).
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 MMC_CMD register must be configured differently to avoid false CRC or index errors to be flagged on command response (see Table 13-241). For more details about response types, see the Multimedia Card System Specification, the SD Memory Card Specification, or the SDIO Card Specification.
Response Type MMC_CMD[17:16] RSP_TYPE(1) | Index Check Enable MMC_CMD[20] CICE | CRC Check Enable MMC_CMD[19] 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 |
Figure 13-179 and Figure 13-180 depict the 48-bit and 136-bit response packets.
Coding Scheme for Data Token
Data tokens always start with 0 and end with 1 (see Figure 13-181, Figure 13-182, Figure 13-183, and Figure 13-184).