SPRUIM2H May 2020 – October 2023 AM2431 , AM2432 , AM2434 , AM6411 , AM6412 , AM6421 , AM6422 , AM6441 , AM6442
The sequence for changing bit mode on SD Bus is shown in Figure 12-1751.
(1) Set MMCSD0_NORMAL_INTR_STS_ENA[8] CARD_INTERRUPT bit to 0 for masking incorrect interrupts that may occur while changing the bus width.
(2) In case of SD memory only card, go to step (4). In case of other card, go to step (3).
(3) Set "IENM" of the CCCR in a SDIO or SD combo card to 0 by CMD52.
(4) Change the bus width mode for a SD card. SD Memory Card bus width is changed by ACMD6 and SDIO card bus width is changed by setting Bus Width of Bus Interface Control register in CCCR.
(5) In case of changing to 4-bit mode, set MMCSD0_HOST_CONTROL1[1] DATA_WIDTH bit to 1. In another case (1-bit mode), set this bit to 0.
(6) In case of SD memory only card, go to the "End". In case of other card, go to step (7).
(7) Set "IENM" of the CCCR in a SDIO or SD combo card to 1 by CMD52.
(8) Set MMCSD0_NORMAL_INTR_STS_ENA[8] CARD_INTERRUPT bit to 1.
Note that if the card is locked, bus width cannot be changed. Unlock the card is required before changing bus width.