SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
Response tokens always start with 0 and end with 1. The second bit is a transmitter bit: 0 for a card response. The content is different for each type of response (R1, R2, R3, R4, and R5, R6, R7 [for SD]) and the content is protected by 7-bit CRC checksum (see Figure 12-2201 and Figure 12-2202). Depending on the type of commands sent to the card, the MMCSD0_COMMAND / MMCSD1_COMMAND register must be configured differently to avoid false CRC or index errors to be flagged on command response (see Table 12-4330). For more information about response types, see the Multi-Media Card System Specification, SD Memory Card Specifications, and SDIO Card Specification (Part E1).
Response Type MMCSD0_COMMAND[1-0] RESP_TYPE_SEL / MMCSD1_COMMAND[1-0] RESP_TYPE_SEL | Index Check Enable MMCSD0_COMMAND[4] CMD_INDEX_CHK_ENA / MMCSD1_COMMAND[4] CMD_INDEX_CHK_ENA | CRC Check Enable MMCSD0_COMMAND[3] CMD_CRC_CHK_ENA / MMCSD1_COMMAND[3] CMD_CRC_CHK_ENA | 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 |