Use case: SDIO direct transfer

A direct I/O transfer accesses a single byte in an SDIO function register space and is commonly used for control/status registers (for example, reading an interrupt status register or writing a configuration value). The sequence and APIs remain unchanged between HAL1 and HAL2.

For example, an SDIO Wi‑Fi device may expose multiple functions where user_io_func_nbr selects the Wi‑Fi function; a direct transfer could then read a status register in the Wi‑Fi function or write a control register.

@startuml hide footbox participant "User Application" as part1 participant "HAL SDIO" as part2 activate part1 activate part2 group Direct I/O access part1->part2 : HAL_SDIO_ReadDirect() part2-->part1 : HAL Status part1->part2 : HAL_SDIO_WriteDirect() part2-->part1 : HAL Status end @enduml

Code Snippet

HAL1/HAL2 

uint8_t reg_value = 0U;

/* Read a single byte from a function register */
if (HAL_SDIO_ReadDirect(&hsdio,
                        user_io_func_nbr,
                        RegisterAddress,
                        &reg_value) != HAL_OK)
{
   Error_Handler();
}

/* Update configuration register */
reg_value |= REG_ENABLE_MASK; /* Example: enable a specific feature */

/* Write back the updated value to the function register */
if (HAL_SDIO_WriteDirect(&hsdio,
                         user_io_func_nbr,
                         RegisterAddress,
                         reg_value) != HAL_OK)
{
   Error_Handler();
}