Flash Interface

Driver API for Flash Device Interface (Driver_Flash.h) More...

Content
	Flash Events
	The Flash driver generates call back events that are notified via the function ARM_Flash_SignalEvent.

Data Structures
struct	ARM_FLASH_SECTOR
	Flash Sector information. More...
struct	ARM_FLASH_INFO
	Flash information. More...
struct	ARM_DRIVER_FLASH
	Access structure of the Flash Driver. More...
struct	ARM_FLASH_CAPABILITIES
	Flash Driver Capabilities. More...
struct	ARM_FLASH_STATUS
	Flash Status. More...

Typedefs
typedef void(*	ARM_Flash_SignalEvent_t) (uint32_t event)
	Pointer to ARM_Flash_SignalEvent : Signal Flash Event.

Functions
ARM_DRIVER_VERSION	ARM_Flash_GetVersion (void)
	Get driver version.
ARM_FLASH_CAPABILITIES	ARM_Flash_GetCapabilities (void)
	Get driver capabilities.
int32_t	ARM_Flash_Initialize (ARM_Flash_SignalEvent_t cb_event)
	Initialize the Flash Interface.
int32_t	ARM_Flash_Uninitialize (void)
	De-initialize the Flash Interface.
int32_t	ARM_Flash_PowerControl (ARM_POWER_STATE state)
	Control the Flash interface power.
int32_t	ARM_Flash_ReadData (uint32_t addr, void *data, uint32_t cnt)
	Read data from Flash.
int32_t	ARM_Flash_ProgramData (uint32_t addr, const void *data, uint32_t cnt)
	Program data to Flash.
int32_t	ARM_Flash_EraseSector (uint32_t addr)
	Erase Flash Sector.
int32_t	ARM_Flash_EraseChip (void)
	Erase complete Flash. Optional function for faster full chip erase.
ARM_FLASH_STATUS	ARM_Flash_GetStatus (void)
	Get Flash status.
ARM_FLASH_INFO *	ARM_Flash_GetInfo (void)
	Get Flash information.
void	ARM_Flash_SignalEvent (uint32_t event)
	Signal Flash event.

Description

Driver API for Flash Device Interface (Driver_Flash.h)

Flash devices based on NOR memory cells are the preferred technology for embedded applications requiring a discrete non-volatile memory device. The low read latency characteristic of these Flash devices allow a direct code execution (XIP) and data storage in a single memory product.

Flash API

The Flash API provides a generic API suitable for Flashes with NOR memory cells independent from the actual interface to the MCU (memory bus, SPI, ...). SPI flashes are typically not named NOR flashes but have usually same flash cell properties.

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

• Driver_Flash.h : Driver API for Flash Device Interface

Driver Functions

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

• ARM_DRIVER_FLASH : access struct for Flash driver functions

A typical setup sequence for the driver is shown below:

Example Code:

#include "Driver_Flash.h"
#include "cmsis_os2.h"                  // ARM::CMSIS:RTOS2:Keil RTX5
   
/* Flash driver instance */
extern ARM_DRIVER_FLASH Driver_Flash0;
static ARM_DRIVER_FLASH * flashDev = &Driver_Flash0;
 
/* CMSIS-RTOS2 Thread Id */
osThreadId_t Flash_Thread_Id;
 
/* Flash signal event */
void Flash_Callback(uint32_t event)
{
  if (event & ARM_FLASH_EVENT_READY) {
    /* The read/program/erase operation is completed */
    osThreadFlagsSet(Flash_Thread_Id, 1U);
  }
  if (event & ARM_FLASH_EVENT_ERROR) {
    /* The read/program/erase operation is completed with errors */
    /* Call debugger or replace with custom error handling */
    __breakpoint(0);  
  }
} 
 
/* CMSIS-RTOS2 Thread */ 
void Flash_Thread (void *argument)
{
  /* Query drivers capabilities */
  const ARM_FLASH_CAPABILITIES capabilities = flashDev->GetCapabilities();
 
  /* Initialize Flash device */
  if (capabilities.event_ready) {
    flashDev->Initialize (&Flash_Callback);
  } else {
    flashDev->Initialize (NULL);
  }
  
  /* Power-on Flash device */
  flashDev->PowerControl (ARM_POWER_FULL);
  
  /* Read data taking data_width into account */
  uint8_t buf[256U];
  flashDev->ReadData (0x1000U, buf, sizeof(buf)>>capabilities.data_width);
  
  /* Wait operation to be completed */
  if (capabilities.event_ready) {
    osThreadFlagsWait (1U, osFlagsWaitAny, 100U);
  } else {
    osDelay(100U);
  }
  
  /* Switch off gracefully */
  flashDev->PowerControl (ARM_POWER_OFF);
  flashDev->Uninitialize ();
}

---

Data Structure Documentation

ARM_FLASH_SECTOR

struct ARM_FLASH_SECTOR

Flash Sector information.

Specifies sector start and end address.

Element of:

• ARM_FLASH_INFO structure

Data Fields
uint32_t	start	Sector Start address.
uint32_t	end	Sector End address (start+size-1)

ARM_FLASH_INFO

struct ARM_FLASH_INFO

Flash information.

Stores the characteristics of a Flash device. This includes sector layout, programming size and a default value for erased memory. This information can be obtained from the Flash device datasheet and is used by the middleware in order to properly interact with the Flash device.

Sector layout is described by specifying the sector_info which points to an array of sector information (start and end address) and by specifying the sector_count which defines the number of sectors. The element sector_size is not used in this case and needs to be 0. Flash sectors need not to be aligned continuously. Gaps are allowed in the device memory space in order to reserve sectors for other usage (for example application code).

When the device has uniform sector size than the sector layout can be described by specifying the sector_size which defines the size of a single sector and by specifying the sector_count which defines the number of sectors. The element sector_info is not used in this case and needs to be NULL.

The smallest programmable unit within a sector is specified by the program_unit. It defines the granularity for programming data.

Optimal programming page size is specified by the page_size and defines the amount of data that should be programmed in one step to achieve maximum programming speed.

Contents of erased memory is specified by the erased_value and is typically 0xFF. This value can be used before erasing a sector to check if the sector is blank and erase can be skipped.

Data Fields
ARM_FLASH_SECTOR *	sector_info	Sector layout information (NULL=Uniform sectors)
uint32_t	sector_count	Number of sectors.
uint32_t	sector_size	Uniform sector size in bytes (0=sector_info used)
uint32_t	page_size	Optimal programming page size in bytes.
uint32_t	program_unit	Smallest programmable unit in bytes.
uint8_t	erased_value	Contents of erased memory (usually 0xFF)
uint8_t	reserved[3]	Reserved (must be zero)

ARM_DRIVER_FLASH

struct ARM_DRIVER_FLASH

Access structure of the Flash Driver.

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

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

• Driver_Flash0 is the name of the access struct of the first instance (no. 0).
• Driver_Flash1 is the name of the access struct of the second instance (no. 1).

A middleware configuration setting allows connecting the middleware to a specific driver instance Driver_Flashn. 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_Flash_GetVersion : Get driver version.
ARM_FLASH_CAPABILITIES(*	GetCapabilities )(void)
	Pointer to ARM_Flash_GetCapabilities : Get driver capabilities.
int32_t(*	Initialize )(ARM_Flash_SignalEvent_t cb_event)
	Pointer to ARM_Flash_Initialize : Initialize Flash Interface.
int32_t(*	Uninitialize )(void)
	Pointer to ARM_Flash_Uninitialize : De-initialize Flash Interface.
int32_t(*	PowerControl )(ARM_POWER_STATE state)
	Pointer to ARM_Flash_PowerControl : Control Flash Interface Power.
int32_t(*	ReadData )(uint32_t addr, void *data, uint32_t cnt)
	Pointer to ARM_Flash_ReadData : Read data from Flash.
int32_t(*	ProgramData )(uint32_t addr, const void *data, uint32_t cnt)
	Pointer to ARM_Flash_ProgramData : Program data to Flash.
int32_t(*	EraseSector )(uint32_t addr)
	Pointer to ARM_Flash_EraseSector : Erase Flash Sector.
int32_t(*	EraseChip )(void)
	Pointer to ARM_Flash_EraseChip : Erase complete Flash.
ARM_FLASH_STATUS(*	GetStatus )(void)
	Pointer to ARM_Flash_GetStatus : Get Flash status.
ARM_FLASH_INFO *(*	GetInfo )(void)
	Pointer to ARM_Flash_GetInfo : Get Flash information.

Field Documentation

GetVersion

ARM_DRIVER_VERSION(* GetVersion) (void)

Pointer to ARM_Flash_GetVersion : Get driver version.

GetCapabilities

ARM_FLASH_CAPABILITIES(* GetCapabilities) (void)

Pointer to ARM_Flash_GetCapabilities : Get driver capabilities.

Initialize

int32_t(* Initialize) (ARM_Flash_SignalEvent_t cb_event)

Pointer to ARM_Flash_Initialize : Initialize Flash Interface.

Uninitialize

int32_t(* Uninitialize) (void)

Pointer to ARM_Flash_Uninitialize : De-initialize Flash Interface.

PowerControl

int32_t(* PowerControl) (ARM_POWER_STATE state)

Pointer to ARM_Flash_PowerControl : Control Flash Interface Power.

ReadData

int32_t(* ReadData) (uint32_t addr, void *data, uint32_t cnt)

Pointer to ARM_Flash_ReadData : Read data from Flash.

ProgramData

int32_t(* ProgramData) (uint32_t addr, const void *data, uint32_t cnt)

Pointer to ARM_Flash_ProgramData : Program data to Flash.

EraseSector

int32_t(* EraseSector) (uint32_t addr)

Pointer to ARM_Flash_EraseSector : Erase Flash Sector.

EraseChip

int32_t(* EraseChip) (void)

Pointer to ARM_Flash_EraseChip : Erase complete Flash.

GetStatus

ARM_FLASH_STATUS(* GetStatus) (void)

Pointer to ARM_Flash_GetStatus : Get Flash status.

GetInfo

ARM_FLASH_INFO *(* GetInfo) (void)

Pointer to ARM_Flash_GetInfo : Get Flash information.

ARM_FLASH_CAPABILITIES

struct ARM_FLASH_CAPABILITIES

Flash Driver Capabilities.

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

The element event_ready indicates that the driver is able to generate the ARM_FLASH_EVENT_READY event. In case that this event is not available it is possible to poll the driver status by calling the ARM_Flash_GetStatus and check the busy flag.

The element data_width specifies the data access size and also defines the data type (uint8_t, uint16_t or uint32_t) for the data parameter in ARM_Flash_ReadData and ARM_Flash_ProgramData functions.

The element erase_chip specifies that the ARM_Flash_EraseChip function is supported. Typically full chip erase is much faster than erasing the whole device sector per sector.

Returned by:

• ARM_Flash_GetCapabilities

Data Fields
uint32_t	event_ready: 1	Signal Flash Ready event.
uint32_t	data_width: 2	Data width: 0=8-bit, 1=16-bit, 2=32-bit.
uint32_t	erase_chip: 1	Supports EraseChip operation.
uint32_t	reserved: 28	Reserved (must be zero)

ARM_FLASH_STATUS

struct ARM_FLASH_STATUS

Flash Status.

Structure with information about the status of the Flash.

The flag busy indicates that the driver is busy executing read/program/erase operation.

The flag error flag is cleared on start of read/program/erase operation and is set at the end of the current operation in case of error.

Returned by:

• ARM_Flash_GetStatus

Data Fields
uint32_t	busy: 1	Flash busy flag.
uint32_t	error: 1	Read/Program/Erase error flag (cleared on start of next operation)
uint32_t	reserved: 30

Typedef Documentation

ARM_Flash_SignalEvent_t

ARM_Flash_SignalEvent_t

Pointer to ARM_Flash_SignalEvent : Signal Flash Event.

Provides the typedef for the callback function ARM_Flash_SignalEvent.

Parameter for:

• ARM_Flash_Initialize

Function Documentation

ARM_Flash_GetVersion()

ARM_DRIVER_VERSION ARM_Flash_GetVersion

(

void

)

Get driver version.

Returns

ARM_DRIVER_VERSION

The function ARM_Flash_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_FLASH Driver_Flash0;
ARM_DRIVER_FLASH *drv_info;
 
void read_version (void)  {
  ARM_DRIVER_VERSION  version;
 
  drv_info = &Driver_Flash0;  
  version = drv_info->GetVersion ();
  if (version.api < 0x10A)   {      // requires at minimum API version 1.10 or higher
    // error handling
    return;
  }
}

ARM_Flash_GetCapabilities()

ARM_FLASH_CAPABILITIES ARM_Flash_GetCapabilities

(

void

)

Get driver capabilities.

Returns

ARM_FLASH_CAPABILITIES

The function ARM_Flash_GetCapabilities returns information about capabilities in this driver implementation. The data fields of the struct ARM_FLASH_CAPABILITIES encode various capabilities, for example if a hardware is able to create signal events using the ARM_Flash_SignalEvent callback function.

Example:

extern ARM_DRIVER_FLASH Driver_Flash0;
ARM_DRIVER_FLASH *drv_info;
  
void read_capabilities (void)  {
  ARM_FLASH_CAPABILITIES drv_capabilities;
 
  drv_info = &Driver_Flash0;  
  drv_capabilities = drv_info->GetCapabilities ();
  // interrogate capabilities
 
}

ARM_Flash_Initialize()

int32_t ARM_Flash_Initialize

(

ARM_Flash_SignalEvent_t

cb_event

)

Initialize the Flash Interface.

Parameters

[in]

cb_event

Pointer to ARM_Flash_SignalEvent

Returns

Status Error Codes

The function ARM_Flash_Initialize initializes the Flash interface. It is called when the middleware component starts operation.

The function performs the following operations:

• Initializes the resources needed for the Flash interface.
• Registers the ARM_Flash_SignalEvent callback function.

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

Example:

• see Flash Interface - Driver Functions

ARM_Flash_Uninitialize()

int32_t ARM_Flash_Uninitialize

(

void

)

De-initialize the Flash Interface.

Returns

Status Error Codes

The function ARM_Flash_Uninitialize de-initializes the resources of Flash interface.

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

ARM_Flash_PowerControl()

int32_t ARM_Flash_PowerControl

(

ARM_POWER_STATE

state

)

Control the Flash interface power.

Parameters

[in]

state

Power state

Returns

Status Error Codes

The function ARM_Flash_PowerControl operates the power modes of the Flash 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_Flash_ReadData()

int32_t ARM_Flash_ReadData	(	uint32_t	addr,
		void *	data,
		uint32_t	cnt
	)

Read data from Flash.

Parameters

[in]	addr	Data address.
[out]	data	Pointer to a buffer storing the data read from Flash.
[in]	cnt	Number of data items to read.

Returns

number of data items read or Status Error Codes

This function ARM_Flash_ReadData reads data from the Flash device.

The parameter addr specifies the address from where to read data (needs to be aligned to data type size).
The parameter data specifies the pointer to a buffer storing the data read. The data type is uint8_t, uint16_t or uint32_t and is specified by the data_width in ARM_FLASH_CAPABILITIES.
The parameter cnt specifies the number of data items to read.

The function executes in the following ways:

• When the operation is non-blocking (typical for SPI Flash) then the function only starts the operation and returns with zero number of data items read. When the operation is completed the ARM_FLASH_EVENT_READY event is generated (if supported and reported by ARM_Flash_GetCapabilities). In case of errors the ARM_FLASH_EVENT_ERROR event is generated at the same time.
  Progress of the operation can also be monitored by calling the ARM_Flash_GetStatus function and checking the busy flag.
• When the operation is blocking (typical for memory mapped Flash) then the function returns after the data is read and returns the number of data items read.

ARM_Flash_ProgramData()

int32_t ARM_Flash_ProgramData	(	uint32_t	addr,
		const void *	data,
		uint32_t	cnt
	)

Program data to Flash.

Parameters

[in]	addr	Data address.
[in]	data	Pointer to a buffer containing the data to be programmed to Flash.
[in]	cnt	Number of data items to program.

Returns

number of data items programmed or Status Error Codes

This function ARM_Flash_ProgramData programs data to the Flash device.

The parameter addr specifies the address to where to program data (needs to be aligned to program_unit specified in ARM_FLASH_INFO).
The parameter data specifies the pointer to a buffer containing data to be programmed. The data type is uint8_t, uint16_t or uint32_t and is specified by the data_width in ARM_FLASH_CAPABILITIES.
The parameter cnt specifies the number of data items to program (data size needs to be a multiple of program_unit).

The function executes in the following ways:

• When the operation is non-blocking (typically) then the function only starts the operation and returns with zero number of data items programmed. When the operation is completed the ARM_FLASH_EVENT_READY event is generated (if supported and reported by ARM_Flash_GetCapabilities). In case of errors the ARM_FLASH_EVENT_ERROR event is generated at the same time. Progress of the operation can also be monitored by calling the ARM_Flash_GetStatus function and checking the busy flag.
• When the operation is blocking then the function returns after the data is programmed and returns the number of data items programmed.

ARM_Flash_EraseSector()

int32_t ARM_Flash_EraseSector

(

uint32_t

addr

)

Erase Flash Sector.

Parameters

[in]

addr

Sector address

Returns

Status Error Codes

This function ARM_Flash_EraseSector erases a flash sector specified by the parameter adr (points to start of the sector).

The function is non-blocking and returns as soon as the driver has started the operation. When the operation is completed the ARM_FLASH_EVENT_READY event is generated (if supported and reported by ARM_Flash_GetCapabilities). In case of errors the ARM_FLASH_EVENT_ERROR event is generated at the same time. Progress of the operation can also be monitored by calling the ARM_Flash_GetStatus function and checking the busy flag.

ARM_Flash_EraseChip()

int32_t ARM_Flash_EraseChip

(

void

)

Erase complete Flash. Optional function for faster full chip erase.

Returns

Status Error Codes

The optional function ARM_Flash_EraseChip erases the complete device. If the device does not support global erase or only a portion of the Flash memory space is used for storing files, then the functions returns the error value ARM_DRIVER_ERROR_UNSUPPORTED. The data field eras_chip = 1 of the structure ARM_FLASH_CAPABILITIES encodes that ARM_Flash_EraseChip is supported. The field can be verified with the function ARM_Flash_GetCapabilities.

The function is non-blocking and returns as soon as the driver has started the operation. When the operation is completed, the ARM_FLASH_EVENT_READY event is generated (if supported and reported by ARM_Flash_GetCapabilities). In case of errors, the ARM_FLASH_EVENT_ERROR event is generated at the same time. Progress of the operation can also be monitored by calling the ARM_Flash_GetStatus function and checking the busy flag.

See also:

• ARM_Flash_SignalEvent

ARM_Flash_GetStatus()

ARM_FLASH_STATUS ARM_Flash_GetStatus

(

void

)

Get Flash status.

Returns

Flash status ARM_FLASH_STATUS

The function ARM_Flash_GetStatus returns the current Flash interface status stored in the structure ARM_FLASH_STATUS.

ARM_Flash_GetInfo()

ARM_FLASH_INFO * ARM_Flash_GetInfo

(

void

)

Get Flash information.

Returns

Pointer to Flash information ARM_FLASH_INFO

The function ARM_Flash_GetInfo returns information about the Flash device.

ARM_Flash_SignalEvent()

void ARM_Flash_SignalEvent

(

uint32_t

event

)

Signal Flash event.

Parameters

[in]

event

Event notification mask

The function ARM_Flash_SignalEvent is a callback function registered by the function ARM_Flash_Initialize. The function is called automatically after read/program/erase operation completes.

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

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

The following events can be generated:

Parameter event	Bit	Description
ARM_FLASH_EVENT_READY	0	Occurs after read/program/erase operation completes.
ARM_FLASH_EVENT_ERROR	1	Occurs together with ARM_FLASH_EVENT_READY when operation completes with errors.

See also:

• ARM_Flash_EraseChip