MCI Interface

Driver API for Memory Card Interface using SD/MMC interface (Driver_MCI.h) More...

Content
	MCI Events
	The MCI driver generates call back events that are notified via the function ARM_MCI_SignalEvent.
	MCI Control Codes
	Configure and control the MCI using the ARM_MCI_Control.
	MCI Send Command Flags
	Specify various options for sending commands to the card and the expected response.
	MCI Transfer Controls
	Specify data transfer mode.
	MCI Card Power Controls
	Specify Memory Card Power supply voltage.

Data Structures
struct	ARM_DRIVER_MCI
	Access structure of the MCI Driver. More...
struct	ARM_MCI_CAPABILITIES
	MCI Driver Capabilities. More...
struct	ARM_MCI_STATUS
	MCI Status. More...

Typedefs
typedef void(*	ARM_MCI_SignalEvent_t) (uint32_t event)
	Pointer to ARM_MCI_SignalEvent : Signal MCI Card Event.

Functions
ARM_DRIVER_VERSION	ARM_MCI_GetVersion (void)
	Get driver version.
ARM_MCI_CAPABILITIES	ARM_MCI_GetCapabilities (void)
	Get driver capabilities.
int32_t	ARM_MCI_Initialize (ARM_MCI_SignalEvent_t cb_event)
	Initialize the Memory Card Interface.
int32_t	ARM_MCI_Uninitialize (void)
	De-initialize Memory Card Interface.
int32_t	ARM_MCI_PowerControl (ARM_POWER_STATE state)
	Control Memory Card Interface Power.
int32_t	ARM_MCI_CardPower (uint32_t voltage)
	Set Memory Card Power supply voltage.
int32_t	ARM_MCI_ReadCD (void)
	Read Card Detect (CD) state.
int32_t	ARM_MCI_ReadWP (void)
	Read Write Protect (WP) state.
int32_t	ARM_MCI_SendCommand (uint32_t cmd, uint32_t arg, uint32_t flags, uint32_t *response)
	Send Command to card and get the response.
int32_t	ARM_MCI_SetupTransfer (uint8_t *data, uint32_t block_count, uint32_t block_size, uint32_t mode)
	Setup read or write transfer operation.
int32_t	ARM_MCI_AbortTransfer (void)
	Abort current read/write data transfer.
int32_t	ARM_MCI_Control (uint32_t control, uint32_t arg)
	Control MCI Interface.
ARM_MCI_STATUS	ARM_MCI_GetStatus (void)
	Get MCI status.
void	ARM_MCI_SignalEvent (uint32_t event)
	Callback function that signals a MCI Card Event.

Description

Driver API for Memory Card Interface using SD/MMC interface (Driver_MCI.h)

The Memory Card Interface (MCI) implements the hardware abstraction layer for Secure Digital (SD) and Multi Media Card (MMC) memory that is typically used as file storage. For embedded systems, SD/MMC devices are available as memory cards in several forms (SD, miniSD, microSD, MMC, MMCmicro) or as non-removable device es that are directly soldered to the PCB (eMMC).

References:

• Wikipedia offers more information about the Secure Digital memory.
• Wikipedia offers more information about the MultiMediaCard.
• The SD Association provides detailed documentation under www.sdcard.org.
• The MultiMediaCard Association (merged with JEDEC) provides detailed documentation under www.jedec.org.

Block Diagram

The MCI driver allows you to exchange data of the SD/MMC memory via SD/MMC interface.

The following modes are supported by SD/MMC memory cards:

• SPI bus mode: Serial Peripheral Interface Bus supported by most microcontrollers.
• 1-bit SD/MMC Bus mode: proprietary data transfer protocol supported by SD/MMC interfaces.
• 4-bit SD/MMC Bus mode: high-speed version of the SD/MMC interface using 4 data I/O pins.
• 8-bit SD/MMC Bus mode: high-speed version of the SD/MMC interface using 8 data I/O pins.

SD memory connected via SPI interface

 

SD memory connected via 1-bit SD Bus Mode

 

SD memory connected via 4-bit SD Bus Mode

MCI API

The following header files define the Application Programming Interface (API) for the MCI interface:

• Driver_MCI.h : Driver API for Memory Card Interface using SD/MMC interface

The driver implementation is a typical part of the Device Family Pack (DFP) that supports the peripherals of the microcontroller family.

Note

For parameters, the value marked with (default) is the setting after the driver initialization.

Driver Functions

The driver functions are published in the access struct as explained in Common Driver Functions

• ARM_DRIVER_MCI : access struct for MCI driver functions

Example Code

The following example code shows the usage of the MCI interface.

 
#include "Driver_MCI.h"
 
 
/* Usage example: ARM_MCI_Initialize ----------------------------------------*/
 
// ARM_MCI_SignalEvent callback function prototype
void MCI_SignalEvent_Callback (uint32_t event);
 
void init_driver (ARM_DRIVER_MCI *drv) {
  int32_t status;
  
  status = drv->Initialize (&MCI_SignalEvent_Callback);
  
  if (status != ARM_DRIVER_OK) {
    // Initialization and event callback registration failed
  }
}
 
/* Usage example: ARM_MCI_Uninitialize --------------------------------------*/
 
void uninit_driver (ARM_DRIVER_MCI *drv) {
  int32_t status;
  
  status = drv->Uninitialize ();
  
  if (status == ARM_DRIVER_OK) {
    // Driver successfully uninitialized
  }
}
 
/* Usage example: ARM_MCI_PowerControl --------------------------------------*/
 
void control_driver_power (ARM_DRIVER_MCI *drv, bool enable) {
  int32_t status;
  
  if (enable == true) {
    status = drv->PowerControl (ARM_POWER_FULL);
  }
  else {
    status = drv->PowerControl (ARM_POWER_OFF);
  }
  
  if (status == ARM_DRIVER_OK) {
    // Driver power enabled/disabled
  }
}
 
/* Usage example: ARM_MCI_CardPower -----------------------------------------*/
 
ARM_MCI_CAPABILITIES drv_capabilities;
 
void set_card_vdd_3v3 (ARM_DRIVER_MCI *drv) {
  int32_t status;
  
  if (drv_capabilities.vdd == 1U) {
    // Power switching to 3.3V supported
    status = drv->CardPower (ARM_MCI_POWER_VDD_3V3);
    
    if (status == ARM_DRIVER_OK) {
      // Card power set to 3.3V
    }
  }
}
 
/* Usage example: ARM_MCI_ReadCD --------------------------------------------*/
 
void read_card_detect_state (ARM_DRIVER_MCI *drv) {
  int32_t status;
  
  status = drv->ReadCD();
  
  if (status == 1) {
    // Memory card is detected
  }
  else {
    if (status == 0) {
      // Memory card is not detected
    }
    else {
      // Error reading card detect pin state
    }
  }
}
 
/* Usage example: ARM_MCI_ReadWP --------------------------------------------*/
 
void read_write_protect_state (ARM_DRIVER_MCI *drv) {
  int32_t status;
  
  status = drv->ReadWP();
  
  if (status == 1) {
    // Memory card write protection is enabled
  }
  else {
    if (status == 0) {
      // Memory card write protection is disabled
    }
    else {
      // Error reading write protect pin state
    }
  }
}
 
/* Usage example: ARM_MCI_SendCommand ---------------------------------------*/
 
volatile uint32_t MCI_Events;
 
void MCI_SignalEvent_Callback (uint32_t event) {
  // Save current event
  MCI_Events |= event;
}
 
void send_CMD0 (ARM_DRIVER_MCI *drv) {
  int32_t  status;
  uint32_t cmd;
 
  MCI_Events = 0U; //Clear MCI driver event flags
  cmd = 0U;        // Set GO_IDLE_STATE command code
 
  status = drv->SendCommand (cmd, 0U, ARM_MCI_CARD_INITIALIZE | ARM_MCI_RESPONSE_NONE, NULL);
 
  if (status == ARM_DRIVER_OK) {
    /* Wait for event */
    while ((MCI_Events & ARM_MCI_EVENT_COMMAND_COMPLETE) == 0U);
    // Command was successfully sent to memory card
    // ..
  }
  else {
    // Error
  }
}
 
/* Usage example: ARM_MCI_SetupTransfer -------------------------------------*/
 
volatile uint32_t MCI_Events;
 
void MCI_SignalEvent_Callback (uint32_t event) {
  MCI_Events |= event;  // Save current event
}
 
void read_sector (ARM_DRIVER_MCI *drv, uint8_t *buf, uint32_t sz) {
  int32_t status;
  uint32_t cmd, arg;
  uint32_t resp;
 
  if (sz < 512U) {
    // Invalid buffer size, sector consists of 512 bytes
    //...
  }
 
  status = drv->SetupTransfer (buf, 1U, 512U, ARM_MCI_TRANSFER_READ | ARM_MCI_TRANSFER_BLOCK);
 
  if (status == ARM_DRIVER_OK) {
    MCI_Events = 0U; //Clear MCI driver event flags
 
    cmd = 17U;       // Set READ_SINGLE_BLOCK command
    arg = 0U;        // Set sector number
 
    status  = drv->SendCommand (cmd, arg, ARM_MCI_RESPONSE_SHORT | ARM_MCI_RESPONSE_CRC | ARM_MCI_TRANSFER_DATA, &resp);
 
    if (status == ARM_DRIVER_OK) {
      /* Wait for event */
      while ((MCI_Events & ARM_MCI_EVENT_COMMAND_COMPLETE) == 0U);
      // Command was successfully sent to memory card
      if ((resp & 0x03U) == 0U) {
        // Sector number is valid, wait until data transfer completes
        while ((MCI_Events & ARM_MCI_EVENT_TRANSFER_COMPLETE) == 0U);
        // Data was successfully read from memory card
        // ...
      }
    }
  }
}
 
/* Usage example: ARM_MCI_AbortTransfer -------------------------------------*/
 
void abort_data_transfer (ARM_DRIVER_MCI *drv) {
  ARM_MCI_STATUS drv_status;
 
  drv_status = drv->GetStatus();
  
  if (drv_status.transfer_active == 1U) {
    // Data transfer is active, abort the transfer
    if (drv->AbortTransfer() == ARM_DRIVER_OK) {
      // Transfer aborted
      // ...
    }
  }
}
 
/* Usage example: ARM_MCI_GetStatus -----------------------------------------*/
 
void check_transfer_status (ARM_DRIVER_MCI *drv) {
  ARM_MCI_STATUS drv_status;
 
  drv_status = drv->GetStatus();
 
  if (drv_status.transfer_active == 1U) {
    // Data transfer is active
  }
  
  if (drv_status.transfer_timeout == 1U) {
    // Data not received, timeout expired
  }
  
  if (drv_status.transfer_error == 1U) {
    // Data transfer ended with error
  }
}
 
/* Usage example: ARM_MCI_SignalEvent ---------------------------------------*/
 
void MCI_SignalEvent_Callback (uint32_t event) {
  if ((event & ARM_MCI_EVENT_CARD_INSERTED) != 0U) {
    // Memory card was inserted into socket
  }
  if ((event & ARM_MCI_EVENT_CARD_REMOVED) != 0U) {
    // Memory card was removed from socket
  }
 
  if ((event & ARM_MCI_EVENT_COMMAND_COMPLETE) != 0U) {
    // Command was successfully sent to memory card
  }
  if ((event & ARM_MCI_EVENT_COMMAND_TIMEOUT) != 0U) {
    // Command response was not received in time
  }
  if ((event & ARM_MCI_EVENT_COMMAND_ERROR) != 0U) {
    // Command response was invalid
  }
 
  if ((event & ARM_MCI_EVENT_TRANSFER_COMPLETE) != 0U) {
    // Data successfully transferred from/to memory card
  }
  if ((event & ARM_MCI_EVENT_TRANSFER_TIMEOUT) != 0U) {
    // Data not transferred from/to memory card, timeout expired
  }
  if ((event & ARM_MCI_EVENT_TRANSFER_ERROR) != 0U) {
    // Data transfer ended with errors
  }
  
  if ((event & ARM_MCI_EVENT_SDIO_INTERRUPT) != 0U) {
    // SD I/O card sent interrupt request
  }
  
  if ((event & ARM_MCI_EVENT_CCS) != 0U) {
    // CE-ATA command completion signal received
  }
  if ((event & ARM_MCI_EVENT_CCS_TIMEOUT) != 0U) {
    // CE-ATA command completion signal wait timeout expired
  }
}

---

Data Structure Documentation

ARM_DRIVER_MCI

struct ARM_DRIVER_MCI

Access structure of the MCI Driver.

The functions of the MCI are accessed by function pointers exposed by this structure. Refer to Common Driver Functions for overview information.

Each instance of an MCI provides such an access structure. The instance is identified by a postfix number in the symbol name of the access structure, for example:

• Driver_MCI0 is the name of the access struct of the first instance (no. 0).
• Driver_MCI1 is the name of the access struct of the second instance (no. 1).

A configuration setting in the middleware allows connecting the middleware to a specific driver instance Driver_MCIn. The default is 0, which connects a middleware to the first instance of a driver.

Data Fields
ARM_DRIVER_VERSION(*	GetVersion )(void)
	Pointer to ARM_MCI_GetVersion : Get driver version.
ARM_MCI_CAPABILITIES(*	GetCapabilities )(void)
	Pointer to ARM_MCI_GetCapabilities : Get driver capabilities.
int32_t(*	Initialize )(ARM_MCI_SignalEvent_t cb_event)
	Pointer to ARM_MCI_Initialize : Initialize MCI Interface.
int32_t(*	Uninitialize )(void)
	Pointer to ARM_MCI_Uninitialize : De-initialize MCI Interface.
int32_t(*	PowerControl )(ARM_POWER_STATE state)
	Pointer to ARM_MCI_PowerControl : Control MCI Interface Power.
int32_t(*	CardPower )(uint32_t voltage)
	Pointer to ARM_MCI_CardPower : Set card power supply voltage.
int32_t(*	ReadCD )(void)
	Pointer to ARM_MCI_ReadCD : Read Card Detect (CD) state.
int32_t(*	ReadWP )(void)
	Pointer to ARM_MCI_ReadWP : Read Write Protect (WP) state.
int32_t(*	SendCommand )(uint32_t cmd, uint32_t arg, uint32_t flags, uint32_t *response)
	Pointer to ARM_MCI_SendCommand : Send Command to card and get the response.
int32_t(*	SetupTransfer )(uint8_t *data, uint32_t block_count, uint32_t block_size, uint32_t mode)
	Pointer to ARM_MCI_SetupTransfer : Setup data transfer operation.
int32_t(*	AbortTransfer )(void)
	Pointer to ARM_MCI_AbortTransfer : Abort current data transfer.
int32_t(*	Control )(uint32_t control, uint32_t arg)
	Pointer to ARM_MCI_Control : Control MCI Interface.
ARM_MCI_STATUS(*	GetStatus )(void)
	Pointer to ARM_MCI_GetStatus : Get MCI status.

Field Documentation

GetVersion

ARM_DRIVER_VERSION(* GetVersion) (void)

Pointer to ARM_MCI_GetVersion : Get driver version.

GetCapabilities

ARM_MCI_CAPABILITIES(* GetCapabilities) (void)

Pointer to ARM_MCI_GetCapabilities : Get driver capabilities.

Initialize

int32_t(* Initialize) (ARM_MCI_SignalEvent_t cb_event)

Pointer to ARM_MCI_Initialize : Initialize MCI Interface.

Uninitialize

int32_t(* Uninitialize) (void)

Pointer to ARM_MCI_Uninitialize : De-initialize MCI Interface.

PowerControl

int32_t(* PowerControl) (ARM_POWER_STATE state)

Pointer to ARM_MCI_PowerControl : Control MCI Interface Power.

CardPower

int32_t(* CardPower) (uint32_t voltage)

Pointer to ARM_MCI_CardPower : Set card power supply voltage.

ReadCD

int32_t(* ReadCD) (void)

Pointer to ARM_MCI_ReadCD : Read Card Detect (CD) state.

ReadWP

int32_t(* ReadWP) (void)

Pointer to ARM_MCI_ReadWP : Read Write Protect (WP) state.

SendCommand

int32_t(* SendCommand) (uint32_t cmd, uint32_t arg, uint32_t flags, uint32_t *response)

Pointer to ARM_MCI_SendCommand : Send Command to card and get the response.

SetupTransfer

int32_t(* SetupTransfer) (uint8_t *data, uint32_t block_count, uint32_t block_size, uint32_t mode)

Pointer to ARM_MCI_SetupTransfer : Setup data transfer operation.

AbortTransfer

int32_t(* AbortTransfer) (void)

Pointer to ARM_MCI_AbortTransfer : Abort current data transfer.

Control

int32_t(* Control) (uint32_t control, uint32_t arg)

Pointer to ARM_MCI_Control : Control MCI Interface.

GetStatus

ARM_MCI_STATUS(* GetStatus) (void)

Pointer to ARM_MCI_GetStatus : Get MCI status.

ARM_MCI_CAPABILITIES

struct ARM_MCI_CAPABILITIES

MCI Driver Capabilities.

A MCI driver can be implemented with different capabilities.
The data fields of this struct encode the capabilities implemented by this driver.

Returned by:

• ARM_MCI_GetCapabilities

Data Fields
uint32_t	cd_state: 1	Card Detect State available.
uint32_t	cd_event: 1	Signal Card Detect change event.
uint32_t	wp_state: 1	Write Protect State available.
uint32_t	vdd: 1	Supports VDD Card Power Supply Control.
uint32_t	vdd_1v8: 1	Supports 1.8 VDD Card Power Supply.
uint32_t	vccq: 1	Supports VCCQ Card Power Supply Control (eMMC)
uint32_t	vccq_1v8: 1	Supports 1.8 VCCQ Card Power Supply (eMMC)
uint32_t	vccq_1v2: 1	Supports 1.2 VCCQ Card Power Supply (eMMC)
uint32_t	data_width_4: 1	Supports 4-bit data.
uint32_t	data_width_8: 1	Supports 8-bit data.
uint32_t	data_width_4_ddr: 1	Supports 4-bit data, DDR (Dual Data Rate) - MMC only.
uint32_t	data_width_8_ddr: 1	Supports 8-bit data, DDR (Dual Data Rate) - MMC only.
uint32_t	high_speed: 1	Supports SD/MMC High Speed Mode.
uint32_t	uhs_signaling: 1	Supports SD UHS-I (Ultra High Speed) 1.8V signaling.
uint32_t	uhs_tuning: 1	Supports SD UHS-I tuning.
uint32_t	uhs_sdr50: 1	Supports SD UHS-I SDR50 (Single Data Rate) up to 50MB/s.
uint32_t	uhs_sdr104: 1	Supports SD UHS-I SDR104 (Single Data Rate) up to 104MB/s.
uint32_t	uhs_ddr50: 1	Supports SD UHS-I DDR50 (Dual Data Rate) up to 50MB/s.
uint32_t	uhs_driver_type_a: 1	Supports SD UHS-I Driver Type A.
uint32_t	uhs_driver_type_c: 1	Supports SD UHS-I Driver Type C.
uint32_t	uhs_driver_type_d: 1	Supports SD UHS-I Driver Type D.
uint32_t	sdio_interrupt: 1	Supports SD I/O Interrupt.
uint32_t	read_wait: 1	Supports Read Wait (SD I/O)
uint32_t	suspend_resume: 1	Supports Suspend/Resume (SD I/O)
uint32_t	mmc_interrupt: 1	Supports MMC Interrupt.
uint32_t	mmc_boot: 1	Supports MMC Boot.
uint32_t	rst_n: 1	Supports RST_n Pin Control (eMMC)
uint32_t	ccs: 1	Supports Command Completion Signal (CCS) for CE-ATA.
uint32_t	ccs_timeout: 1	Supports Command Completion Signal (CCS) timeout for CE-ATA.
uint32_t	reserved: 3	Reserved (must be zero)

ARM_MCI_STATUS

struct ARM_MCI_STATUS

MCI Status.

Structure with information about the status of the MCI.

Returned by:

• ARM_MCI_GetStatus

Data Fields
uint32_t	command_active: 1	Command active flag.
uint32_t	command_timeout: 1	Command timeout flag (cleared on start of next command)
uint32_t	command_error: 1	Command error flag (cleared on start of next command)
uint32_t	transfer_active: 1	Transfer active flag.
uint32_t	transfer_timeout: 1	Transfer timeout flag (cleared on start of next command)
uint32_t	transfer_error: 1	Transfer error flag (cleared on start of next command)
uint32_t	sdio_interrupt: 1	SD I/O Interrupt flag (cleared on start of monitoring)
uint32_t	ccs: 1	CCS flag (cleared on start of next command)
uint32_t	reserved: 24

Typedef Documentation

ARM_MCI_SignalEvent_t

ARM_MCI_SignalEvent_t

Pointer to ARM_MCI_SignalEvent : Signal MCI Card Event.

Provides the typedef for the callback function ARM_MCI_SignalEvent.

Parameter for:

• ARM_MCI_Initialize

Function Documentation

ARM_MCI_GetVersion()

ARM_DRIVER_VERSION ARM_MCI_GetVersion

(

void

)

Get driver version.

Returns

ARM_DRIVER_VERSION

The function ARM_MCI_GetVersion returns version information of the driver implementation in ARM_DRIVER_VERSION

• API version is the version of the CMSIS-Driver specification used to implement this driver.
• Driver version is source code version of the actual driver implementation.

Example:

extern ARM_DRIVER_MCI Driver_MCI0;
ARM_DRIVER_MCI *drv_info;
 
void setup_mci (void)  {
  ARM_DRIVER_VERSION  version;
 
  drv_info = &Driver_MCI0;
  version = drv_info->GetVersion ();
  if (version.api < 0x10A)   {      // requires at minimum API version 1.10 or higher
    // error handling
    return;
  }
}

ARM_MCI_GetCapabilities()

ARM_MCI_CAPABILITIES ARM_MCI_GetCapabilities

(

void

)

Get driver capabilities.

Returns

ARM_MCI_CAPABILITIES

The function ARM_MCI_GetCapabilities returns information about capabilities in this driver implementation. The data fields of the structure ARM_MCI_CAPABILITIES encode various capabilities, for example supported bus modes ...

Example:

extern ARM_DRIVER_MCI Driver_MCI0;
ARM_DRIVER_MCI *drv_info;
  
void read_capabilities (void)  {
  ARM_MCI_CAPABILITIES drv_capabilities;
 
  drv_info = &Driver_MCI0;  
  drv_capabilities = drv_info->GetCapabilities ();
  // interrogate capabilities
 
}

ARM_MCI_Initialize()

int32_t ARM_MCI_Initialize

(

ARM_MCI_SignalEvent_t

cb_event

)

Initialize the Memory Card Interface.

Parameters

[in]

cb_event

Pointer to ARM_MCI_SignalEvent

Returns

Status Error Codes

The function ARM_MCI_Initialize initializes the MCI interface. It is called when the middleware component starts operation.

The function performs the following operations:

• Initializes the resources needed for the MCI interface.
• Registers the ARM_MCI_SignalEvent callback function.

The parameter cb_event is a pointer to the ARM_MCI_SignalEvent callback function; use a NULL pointer when no callback signals are required.

Example:

• see MCI Interface - Driver Functions

ARM_MCI_Uninitialize()

int32_t ARM_MCI_Uninitialize

(

void

)

De-initialize Memory Card Interface.

Returns

Status Error Codes

The function ARM_MCI_Uninitialize de-initializes the resources of I2C interface.

It is called when the middleware component stops operation and releases the software resources used by the interface.

ARM_MCI_PowerControl()

int32_t ARM_MCI_PowerControl

(

ARM_POWER_STATE

state

)

Control Memory Card Interface Power.

Parameters

[in]

state

Power state ARM_POWER_STATE

Returns

Status Error Codes

The function ARM_MCI_PowerControl operates the power modes of the MCI interface.

The parameter state can have the following values:

• ARM_POWER_FULL : set-up peripheral for data transfers, enable interrupts (NVIC) and optionally DMA. Can be called multiple times. If the peripheral is already in this mode, then the function performs no operation and returns with ARM_DRIVER_OK.
• ARM_POWER_LOW : may use power saving. Returns ARM_DRIVER_ERROR_UNSUPPORTED when not implemented.
• ARM_POWER_OFF : terminates any pending data transfers, disables peripheral, disables related interrupts and DMA.

Refer to Function Call Sequence for more information.

ARM_MCI_CardPower()

int32_t ARM_MCI_CardPower

(

uint32_t

voltage

)

Set Memory Card Power supply voltage.

Parameters

[in]

voltage

Memory Card Power supply voltage

Returns

Status Error Codes

The function ARM_MCI_CardPower operates the memory card power supply voltage.

The parameter voltage sets the voltage. Not every voltage might be supported by the driver implementation. The structure ARM_MCI_CAPABILITIES encodes the supported voltage. Retrieve the information with the function ARM_MCI_GetCapabilities and verify the data fields.

The following values:

Parameter voltage	Description	supported when ARM_MCI_CAPABILITIES
ARM_MCI_POWER_VDD_OFF	VDD (VCC) turned off	always supported
ARM_MCI_POWER_VDD_3V3	VDD (VCC) = 3.3V	data field vdd = 1
ARM_MCI_POWER_VDD_1V8	VDD (VCC) = 1.8V	data field vdd_1v8 = 1
ARM_MCI_POWER_VCCQ_OFF	eMMC VCCQ turned off	always supported
ARM_MCI_POWER_VCCQ_3V3	eMMC VCCQ = 3.3V	data field vccq = 1
ARM_MCI_POWER_VCCQ_1V8	eMMC VCCQ = 1.8V	data field vccq_1v8 = 1
ARM_MCI_POWER_VCCQ_1V2	eMMC VCCQ = 1.2V	data field vccq_1v2 = 1

ARM_MCI_ReadCD()

int32_t ARM_MCI_ReadCD

(

void

)

Read Card Detect (CD) state.

Returns

1:card detected, 0:card not detected, or error

The function ARM_MCI_ReadCD reads the status of the Card Detect (CD) pin.

ARM_MCI_ReadWP()

int32_t ARM_MCI_ReadWP

(

void

)

Read Write Protect (WP) state.

Returns

1:write protected, 0:not write protected, or error

The function ARM_MCI_ReadWP reads the status of the Write Protect (WP) pin.

ARM_MCI_SendCommand()

int32_t ARM_MCI_SendCommand	(	uint32_t	cmd,
		uint32_t	arg,
		uint32_t	flags,
		uint32_t *	response
	)

Send Command to card and get the response.

Parameters

[in]	cmd	Memory Card command
[in]	arg	Command argument
[in]	flags	Command flags
[out]	response	Pointer to buffer for response

Returns

Status Error Codes

The function ARM_MCI_SendCommand

• sends commands to the memory card
• retrieve the response from the card
• optionally, start the data transfer.

The parameter cmd is the command sent to the card.
The parameter arg contains arguments for the command cmd.
The parameter flags controls the behavior of the operation and takes predefined values listed in the table below.
The parameter response is a pointer to receive data.

The parameter flags can have the following values:

Parameter flags	Description
ARM_MCI_RESPONSE_NONE	No response expected (default)
ARM_MCI_RESPONSE_SHORT	Short response (48-bit) expected
ARM_MCI_RESPONSE_SHORT_BUSY	Short response with busy signal (48-bit) expected
ARM_MCI_RESPONSE_LONG	Long response (136-bit) expected
ARM_MCI_RESPONSE_INDEX	Check command index in response
ARM_MCI_RESPONSE_CRC	Check CRC in response
ARM_MCI_WAIT_BUSY	Wait until busy before sending the command
ARM_MCI_TRANSFER_DATA	Activate Data transfer
ARM_MCI_CARD_INITIALIZE	Execute Memory Card initialization sequence
ARM_MCI_INTERRUPT_COMMAND	Send Interrupt command (CMD40 - MMC only)
ARM_MCI_INTERRUPT_RESPONSE	Send Interrupt response (CMD40 - MMC only)
ARM_MCI_BOOT_OPERATION	Execute Boot operation (MMC only)
ARM_MCI_BOOT_ALTERNATIVE	Execute Alternative Boot operation (MMC only)
ARM_MCI_BOOT_ACK	Expect Boot Acknowledge (MMC only)
ARM_MCI_CCSD	Send Command Completion Signal Disable (CCSD) for CE-ATA device
ARM_MCI_CCS	Expect Command Completion Signal (CCS) for CE-ATA device

Calling the function ARM_MCI_SendCommand only starts the operation. The function is non-blocking and returns as soon as the driver has started the operation. It is not allowed to call this function again until the operation is in progress.

After the command is sent the response is retrieved if specified with ARM_MCI_RESPONSE_xxx flags. When the command completes successfully (requested response is received without errors) the ARM_MCI_EVENT_COMMAND_COMPLETE event is generated. In case that response is requested but not received the ARM_MCI_EVENT_COMMAND_TIMEOUT event is generated instead. In case of invalid response (or CRC error) the ARM_MCI_EVENT_COMMAND_ERROR event is generated instead. Progress of command operation can be monitored by calling the ARM_MCI_GetStatus and checking the command_active flag.

After the command operation the data transfer operation is started if specified with ARM_MCI_TRANSFER_DATA flag. The data transfer needs to be configured before that by calling the ARM_MCI_SetupTransfer. When the data transfer completes successfully the ARM_MCI_EVENT_TRANSFER_COMPLETE event is generated. In case that data transfer is not completed in-time (specified by ARM_MCI_DATA_TIMEOUT) the ARM_MCI_EVENT_TRANSFER_TIMEOUT event is generated instead. In case of CRC errors the ARM_MCI_EVENT_TRANSFER_ERROR event is generated instead. Progress of data transfer operation can be monitored by calling the ARM_MCI_GetStatus and checking the transfer_active flag.

See also:

• ARM_MCI_SignalEvent

ARM_MCI_SetupTransfer()

int32_t ARM_MCI_SetupTransfer	(	uint8_t *	data,
		uint32_t	block_count,
		uint32_t	block_size,
		uint32_t	mode
	)

Setup read or write transfer operation.

Parameters

[in,out]	data	Pointer to data block(s) to be written or read
[in]	block_count	Number of blocks
[in]	block_size	Size of a block in bytes
[in]	mode	Transfer mode

Returns

Status Error Codes

The function ARM_MCI_SetupTransfer prepares the data transfer operation that is initiated by calling the function ARM_MCI_SendCommand with the parameter flags = ARM_MCI_TRANSFER_DATA.

The parameter data is a pointer to the data to transfer.
The parameter block_count is the number of blocks to transfer.
The parameter block_size is the size of a block.
The parameter mode sets the transfer mode and can have the values liste in the table below:

Transfer Directions	Description
ARM_MCI_TRANSFER_READ	Read data from MCI
ARM_MCI_TRANSFER_WRITE	Write data to MCI
ARM_MCI_TRANSFER_BLOCK (default)	Block Data transfer
ARM_MCI_TRANSFER_STREAM	Stream Data transfer (MMC only)

ARM_MCI_AbortTransfer()

int32_t ARM_MCI_AbortTransfer

(

void

)

Abort current read/write data transfer.

Returns

Status Error Codes

The function ARM_MCI_AbortTransfer aborts the active data transfer operation initiated with ARM_MCI_SendCommand.

ARM_MCI_Control()

int32_t ARM_MCI_Control	(	uint32_t	control,
		uint32_t	arg
	)

Control MCI Interface.

Parameters

[in]	control	Operation
[in]	arg	Argument of operation (optional)

Returns

Status Error Codes

Th function ARM_MCI_Control controls the MCI interface and executes various operations.

The parameter control specifies the operation.
Values for control cannot be ORed, but must be called separately in the code.
The parameter arg provides, depending on the operation, additional information or sets values.

Note

For parameters, the values marked with (default) are the setting after the driver initialization.

The table lists values for the parameter control.

Parameter control	Operation
ARM_MCI_BUS_SPEED	Set the Bus Speed. The parameter arg specifies the speed in bits/s; The function returns the bus speed configured in bits/s.
ARM_MCI_BUS_SPEED_MODE	Set the Bus Speed Mode. Predefined values for arg are listed in the table Bus Speed Mode.
ARM_MCI_BUS_CMD_MODE	Set the CMD Line Mode. Predefined values for arg are listed in the table Bus CMD Line Mode.
ARM_MCI_BUS_DATA_WIDTH	Set data bus width. Predefined values for arg are encoded in Bus Data Width.
ARM_MCI_DRIVER_STRENGTH	Set driver strength. Predefined values for arg are listed in the table Driver Type
ARM_MCI_CONTROL_RESET	Control optional RST_n Pin (eMMC). The parameter arg can have the values [0:inactive(default); 1:active]
ARM_MCI_CONTROL_CLOCK_IDLE	Control clock generation on CLK Pin when idle. The parameter arg can have the values [0:disabled; 1:enabled]
ARM_MCI_UHS_TUNING_OPERATION	Sampling clock Tuning operation (SD UHS-I). The parameter arg can have the values [0:reset; 1:execute]
ARM_MCI_UHS_TUNING_RESULT	Sampling clock Tuning result (SD UHS-I). Returns [0:done; 1:in progress; -1:error]
ARM_MCI_DATA_TIMEOUT	Set Data timeout; The parameter arg sets the timeout in bus cycles.
ARM_MCI_CSS_TIMEOUT	Set Command Completion Signal (CCS) timeout. The parameter arg sets timeout in bus cycles.
ARM_MCI_MONITOR_SDIO_INTERRUPT	Monitor SD I/O interrupt. The parameter arg can have the values [0:disabled(default); 1:enabled]. Monitoring is automatically disabled when an interrupt is recognized.
ARM_MCI_CONTROL_READ_WAIT	Control Read/Wait states for SD I/O. The parameter arg can have the values [0:disabled(default); 1:enabled].
ARM_MCI_SUSPEND_TRANSFER	Suspend Data transfer (SD I/O). Returns the number of remaining bytes to transfer.
ARM_MCI_RESUME_TRANSFER	Resume Data transfer (SD I/O).

Bus Speed Mode

The function ARM_MCI_GetCapabilities lists the supported bus speed modes. Initially, all SD cards use a 3.3 volt electrical interface. Some SD cards can switch to 1.8 volt operation. For example, the use of ultra-high-speed (UHS) SD cards requires 1.8 volt operation and a 4-bit bus data width. The bit field ARM_MCI_CAPABILITIES.uhs_signaling encodes whether the driver supports 1.8 volt UHS signaling.

The control operation ARM_MCI_BUS_SPEED_MODE sets the bus speed mode using the parameter arg.

Parameter arg	Bus Speed Mode
ARM_MCI_BUS_DEFAULT_SPEED (default)	Set the bus speed for SD/MMC cards: Default Speed mode up to [25;26]MHz
ARM_MCI_BUS_HIGH_SPEED	Set the bus speed for SD/MMC: High Speed mode up to [50;52]MHz
ARM_MCI_BUS_UHS_SDR12	Set the bus speed for SD: SDR12 (Single Data Rate) up to 25MHz, 12.5MB/s: UHS-I (Ultra High Speed) 1.8V signalling
ARM_MCI_BUS_UHS_SDR25	Set the bus speed for SD: SDR25 (Single Data Rate) up to 50MHz, 25 MB/s: UHS-I (Ultra High Speed) 1.8V signalling
ARM_MCI_BUS_UHS_SDR50	Set the bus speed for SD: SDR50 (Single Data Rate) up to 100MHz, 50 MB/s: UHS-I (Ultra High Speed) 1.8V signalling
ARM_MCI_BUS_UHS_SDR104	Set the bus speed for SD: SDR104 (Single Data Rate) up to 208MHz, 104 MB/s: UHS-I (Ultra High Speed) 1.8V signalling
ARM_MCI_BUS_UHS_DDR50	Set the bus speed for SD: DDR50 (Dual Data Rate) up to 50MHz, 50 MB/s: UHS-I (Ultra High Speed) 1.8V signalling

Bus CMD Line Mode

The control operation ARM_MCI_BUS_CMD_MODE sets the bus command line mode using the parameter arg.

Parameter arg	Bus CMD Line Mode
ARM_MCI_BUS_CMD_PUSH_PULL (default)	Set the Push-Pull CMD line
ARM_MCI_BUS_CMD_OPEN_DRAIN	Set the Open Drain CMD line (MMC only)

Bus Data Width

Specifies the bus data width (the number of data I/O pins on the SD/MMC interface).

For high speed memory cards, a 4-bit bus data width should be used (or 8-bit for eMMC). The bit fields ARM_MCI_CAPABILITIES.data_width_4 and ARM_MCI_CAPABILITIES.data_width_8 encode whether the driver supports a specific bus data with.

The control operation ARM_MCI_BUS_DATA_WIDTH sets the bus data width using the parameter arg.

Parameter arg	Bus Data Width
ARM_MCI_BUS_DATA_WIDTH_1 (default)	Set the Bus data width to 1 bit
ARM_MCI_BUS_DATA_WIDTH_4	Set the Bus data width to 4 bits
ARM_MCI_BUS_DATA_WIDTH_8	Set the Bus data width to 8 bits
ARM_MCI_BUS_DATA_WIDTH_4_DDR	Set the Bus data width to 4 bits, DDR (Dual Data Rate) - MMC only
ARM_MCI_BUS_DATA_WIDTH_8_DDR	Set the Bus data width to 8 bits, DDR (Dual Data Rate) - MMC only

Driver Type

Specifies the interface driver type.

The control operation ARM_MCI_DRIVER_STRENGTH sets the interface driver type using the parameter arg.

Parameter arg	Driver Type
ARM_MCI_DRIVER_TYPE_A	Set the interface to SD UHS-I Driver Type A
ARM_MCI_DRIVER_TYPE_B (default)	Set the interface to SD UHS-I Driver Type B
ARM_MCI_DRIVER_TYPE_C	Set the interface to SD UHS-I Driver Type C
ARM_MCI_DRIVER_TYPE_D	Set the interface to SD UHS-I Driver Type D

Examples:

// Set Bus Speed to 25MHz
MCIdrv->Control(ARM_MCI_BUS_SPEED, 25000000);
 
// Set High Speed mode
MCIdrv->Control(ARM_MCI_BUS_SPEED_MODE, ARM_MCI_BUS_HIGH_SPEED);
 
// Configure CMD line as Open Drain (MMC only)
MCIdrv->Control(ARM_MCI_BUS_CMD_MODE, ARM_MCI_BUS_CMD_OPEN_DRAIN);
 
// Set Bus Data Width = 4bits
MCIdrv->Control(ARM_MCI_BUS_DATA_WIDTH, ARM_MCI_BUS_DATA_WIDTH_4);
 
// Set SD UHS-I Driver Type B
MCIdrv->Control(ARM_MCI_DRIVER_STRENGTH, ARM_MCI_DRIVER_TYPE_B);
 
// RTS_n Pin is not active by default
// Assert RTS_n Pin (eMMC)
MCIdrv->Control(ARM_MCI_CONTROL_RESET, 1);
// De-assert RTS_n Pin (eMMC)
MCIdrv->Control(ARM_MCI_CONTROL_RESET, 0);
 
// Clock generation on CLK when Idle: hardware specific default behavior
// Enable Clock generation on CLK when Idle
MCIdrv->Control(ARM_MCI_CONTROL_CLOCK_IDLE, 1);
// Disable Clock generation on CLK when Idle
MCIdrv->Control(ARM_MCI_CONTROL_CLOCK_IDLE, 0);
 
// UHS Tuning
MCIdrv->Control(ARM_MCI_UHS_TUNING_OPERATION, 1);  // start tuning
do {
  status = MCIdrv->Control(ARM_MCI_UHS_TUNING_RESULT, 0/*argument not used*/);
  if (status == -1) { break; /* tuning failed */ }
} while (status == 1);
 
// Set Data Timeout to 12500000 bus cycles (0.5s @25MHz Bus Speed)
// Default value is hardware specific (typically 2^32-1)
MCIdrv->Control(ARM_MCI_DATA_TIMEOUT, 12500000);
  
// Set CSS Timeout to 1000000 bus cycles
// Default value is hardware specific
MCIdrv->Control(ARM_MCI_CSS_TIMEOUT, 1000000);
 
// SD I/O Interrupt Monitoring is disabled by default
// Enable SD I/O Interrupt Monitoring
MCIdrv->Control(ARM_MCI_MONITOR_SDIO_INTERRUPT, 1);
// Disable SD I/O Interrupt Monitoring
MCIdrv->Control(ARM_MCI_MONITOR_SDIO_INTERRUPT, 0);
 
// Read/Wait for SD I/O is disabled by default
// Enable Read/Wait for SD I/O
MCIdrv->Control(ARM_MCI_CONTROL_READ_WAIT, 1);
// Disable Read/Wait for SD I/O
MCIdrv->Control(ARM_MCI_CONTROL_READ_WAIT, 0);
 
// Suspend Data transfer (SD I/O)
MCIdrv->Control(ARM_MCI_SUSPEND_TRANSFER, 0/*argument not used*/);
 
// Resume Data transfer (SD I/O)
MCIdrv->Control(ARM_MCI_RESUME_TRANSFER, 0/*argument not used*/);

ARM_MCI_GetStatus()

ARM_MCI_STATUS ARM_MCI_GetStatus

(

void

)

Get MCI status.

Returns

MCI status ARM_MCI_STATUS

The function ARM_MCI_GetStatus returns the current MCI interface status.

ARM_MCI_SignalEvent()

void ARM_MCI_SignalEvent

(

uint32_t

event

)

Callback function that signals a MCI Card Event.

Parameters

[in]

event

MCI Events

The function ARM_MCI_SignalEvent is a callback function registered by the function ARM_MCI_Initialize.

The parameter event indicates one or more events that occurred during driver operation. Each event is encoded in a separate bit and therefore it is possible to signal multiple events within the same call.

Not every event is necessarily generated by the driver. This depends on the implemented capabilities stored in the data fields of the structure ARM_NAND_CAPABILITIES, which can be retrieved with the function ARM_NAND_GetCapabilities.

The following events can be generated:

Parameter event	Bit	Description	supported when ARM_NAND_CAPABILITIES
ARM_MCI_EVENT_CARD_INSERTED	0	Occurs after Memory Card inserted	always supported
ARM_MCI_EVENT_CARD_REMOVED	1	Occurs after Memory Card removal	always supported
ARM_MCI_EVENT_COMMAND_COMPLETE	2	Occurs after command completed successfully	always supported
ARM_MCI_EVENT_COMMAND_TIMEOUT	3	Occurs after command timeout	always supported
ARM_MCI_EVENT_COMMAND_ERROR	4	Occurs after command response error (CRC error or invalid response)	always supported
ARM_MCI_EVENT_TRANSFER_COMPLETE	5	Occurs after data transfer completed successfully	always supported
ARM_MCI_EVENT_TRANSFER_TIMEOUT	6	Occurs after data transfer timeout	always supported
ARM_MCI_EVENT_TRANSFER_ERROR	7	Occurs after data transfer error (CRC failed)	always supported
ARM_MCI_EVENT_SDIO_INTERRUPT	8	Indicates SD I/O Interrupt	data field sdio_interrupt = 1
ARM_MCI_EVENT_CCS	9	Indicates a Command Completion Signal (CCS)	data field ccs = 1
ARM_MCI_EVENT_CCS_TIMEOUT	10	Indicates a Command Completion Signal (CCS) Timeout	data field css_timeout = 1

See also:

• ARM_MCI_SendCommand