SWRU612 December 2023 CC3300 , CC3301 , CC3301MOD , CC3351
SDIO is the main host interface for wireless communication. The CC33xx device also supports shared SDIO interface for both Wi-Fi and Bluetooth Low Energy protocols.
As per the SDIO specification, the host expects these data lines to be pulled up (SDIO_D0, SDIO_D1, SDIO_D2, SDIO_03, SDIO_CMD). It is recommended to take care that any component (for example, level shifters) on the SDIO data lines do not change the state to logic-low.