SDHC Peripheral Driver

Overview

This section describes the programming interface of the SDCH Peripheral driver. The SDHC driver configures the secure digital host controller and provides an easy way to operate the SDHC module.

SDHC Initialization

To initialize the SDHC module, call the SDHC_DRV_Init() function and pass in the configuration data structure.
This is an example code to initialize and configure the driver:

// Define device configuration.
sdhc_user_config_t config = {0};

config.clock = 0;

// Initialize
if (SDHC_DRV_Init(instance, &host, &config) != kStatus_SDHC_NoError)
{
    // error occurs //
}
else
{
    // SDHC has been successfully initialized //
}

SDHC Issuing a request to the card

The SDHC driver provides a simple way to send commands to and retrieve response/data from the card.

This is a example to send the SD_SWITCH command to the card.

sdhc_request_t req = {0};
sdhc_data_t data = {0};

req.cmdIndex = kSdSwitch;                               //  Set command index //
req.argument = mode << 31 | 0x00FFFFFF;                 //  Set argument //
req.argument &= ~((0xF) << (group * 4));
req.argument |= value << (group * 4);
req.flags = FSL_SDHC_REQ_FLAGS_DATA_READ;               //  Set command flags //
req.respType = kSdhcRespTypeR1;                         // Set response type //

data.blockSize = 64;                                    //  Set data block size //
data.blockCount = 1;                                    //  Set data block count //
data.buffer = response;                                 //  Set data buffer //

// link data, command with request //
data.req = &req
req.data = &data;
if (kStatus_SDHC_NoError != SDHC_DRV_IssueRequestBlocking(card->hostInstance,
                                    &req,
                                    FSL_SDCARD_REQUEST_TIMEOUT);)  // issue request //
{
    // error occurs //
}
else
{
    // request has been issued successfully //
}

This section describes the programming interface of the SDCH Peripheral Driver.

SDHC PD FUNCTION
sdhc_status_t	SDHC_DRV_Init (uint32_t instance, sdhc_host_t *host, const sdhc_user_config_t *config)
	Initializes the Host controller with a specific instance index. More...
sdhc_status_t	SDHC_DRV_Shutdown (uint32_t instance)
	Destroys the host controller. More...
sdhc_status_t	SDHC_DRV_DetectCard (uint32_t instance)
	Checks whether the card is present on a specified host controller. More...
sdhc_status_t	SDHC_DRV_ConfigClock (uint32_t instance, uint32_t clock)
	Sets the clock frequency of the host controller. More...
sdhc_status_t	SDHC_DRV_SetBusWidth (uint32_t instance, sdhc_buswidth_t busWidth)
	Sets the bus width of the host controller. More...
sdhc_status_t	SDHC_DRV_IssueRequestBlocking (uint32_t instance, sdhc_request_t *req, uint32_t timeoutInMs)
	Issues the request on a specific host controller and returns on completion. More...
void	SDHC_DRV_DoIrq (uint32_t instance)
	IRQ handler for SDHC. More...

Function Documentation

sdhc_status_t SDHC_DRV_Init	(	uint32_t	instance,
		sdhc_host_t *	host,
		const sdhc_user_config_t *	config
	)

This function initializes the SDHC module according to the given initialization configuration structure including the clock frequency, bus width, and card detect callback.

Parameters

instance	the specific instance index
host	pointer to a place storing the sdhc_host_t structure
config	initialization configuration data

Returns

kStatus_SDHC_NoError if success

sdhc_status_t SDHC_DRV_Shutdown

(

uint32_t

instance

)

Parameters

instance

the instance index of host controller

Returns

kStatus_SDHC_NoError if success

sdhc_status_t SDHC_DRV_DetectCard

(

uint32_t

instance

)

This function checks if there's a card inserted in the SDHC.

Parameters

instance

the instance index of host controller

Returns

kStatus_SDHC_NoError on success

sdhc_status_t SDHC_DRV_ConfigClock	(	uint32_t	instance,
		uint32_t	clock
	)

Parameters

instance	the instance index of host controller
clock	the desired frequency to be set to controller

Returns

kStatus_SDHC_NoError on success

sdhc_status_t SDHC_DRV_SetBusWidth	(	uint32_t	instance,
		sdhc_buswidth_t	busWidth
	)

Parameters

instance	the instance index of host controller
busWidth	the desired bus width to be set to controller

Returns

kStatus_SDHC_NoError on success

sdhc_status_t SDHC_DRV_IssueRequestBlocking	(	uint32_t	instance,
		sdhc_request_t *	req,
		uint32_t	timeoutInMs
	)

This function issues the request to the card on a specific SDHC. The command is sent and is blocked as long as the response/data is sending back from the card.

Parameters

instance	the instance index of host controller
req	the pointer to the request
timeoutInMs	timeout value in microseconds

Returns

kStatus_SDHC_NoError on success

void SDHC_DRV_DoIrq

(

uint32_t

instance

)

This function deals with IRQs on the given host controller.

Parameters

instance

the instance index of host controller