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DataFlash block device

DataFlashBlockDevice is a block device driver for I2C-based EEPROM devices, such as the Adesto AT45DB series of devices.

DataFlash is a memory protocol that combines flash with SRAM buffers for a programming interface. DataFlash supports byte-sized read and writes, with an erase size of around 528 bytes or sometimes 1056 bytes. DataFlash provides erase sizes with an extra 16 bytes for error correction codes (ECC), so a flash translation layer (FTL) may still present 512 byte erase sizes.

You can configure the DataFlashBlockDevice to force the underlying device to use either the binary size (in other words, 512 bytes) or the raw DataFlash size (in other words, 528 bytes).

To configure this class, please see our BlockDevice configuration documentation.

DataFlashBlockDevice class reference

Public Member Functions
 DataFlashBlockDevice (PinName mosi, PinName miso, PinName sclk, PinName csel, int freq=MBED_CONF_DATAFLASH_SPI_FREQ, PinName nowp=NC)
 Creates a DataFlashBlockDevice on a SPI bus specified by pins. More...
virtual int init ()
 Initialize a block device. More...
virtual int deinit ()
 Deinitialize a block device. More...
virtual int read (void *buffer, mbed::bd_addr_t addr, mbed::bd_size_t size)
 Read blocks from a block device. More...
virtual int program (const void *buffer, mbed::bd_addr_t addr, mbed::bd_size_t size)
 Program blocks to a block device. More...
virtual int erase (mbed::bd_addr_t addr, mbed::bd_size_t size)
 Erase blocks on a block device. More...
virtual mbed::bd_size_t get_read_size () const
 Get the size of a readable block. More...
virtual mbed::bd_size_t get_program_size () const
 Get the size of a programable block. More...
virtual mbed::bd_size_t get_erase_size () const
 Get the size of a eraseable block. More...
virtual mbed::bd_size_t get_erase_size (mbed::bd_addr_t addr) const
 Get the size of an erasable block given address. More...
virtual mbed::bd_size_t size () const
 Get the total size of the underlying device. More...
virtual const char * get_type () const
 Get the BlockDevice class type. More...
virtual int sync ()
 Ensure data on storage is in sync with the driver. More...
virtual int trim (bd_addr_t addr, bd_size_t size)
 Mark blocks as no longer in use. More...
virtual int get_erase_value () const
 Get the value of storage when erased. More...
bool is_valid_read (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block read validity. More...
bool is_valid_program (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block program validity. More...
bool is_valid_erase (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block erase validity. More...
Static Public Member Functions
static BlockDeviceget_default_instance ()
 Return the default block device. More...

DataFlashBlockDevice example:

// Here's an example using the AT45DB on the K64F
#include "mbed.h"
#include "DataFlashBlockDevice.h"

// Create DataFlash on SPI bus with PTE5 as chip select
DataFlashBlockDevice dataflash(PTE2, PTE4, PTE1, PTE5);

// Create DataFlash on SPI bus with PTE6 as write-protect
DataFlashBlockDevice dataflash2(PTE2, PTE4, PTE1, PTE5, PTE6);

int main() {
    printf("dataflash test\n");

    // Initialize the SPI flash device and print the memory layout
    dataflash.init();
    printf("dataflash size: %llu\n", dataflash.size());
    printf("dataflash read size: %llu\n", dataflash.get_read_size());
    printf("dataflash program size: %llu\n", dataflash.get_program_size());
    printf("dataflash erase size: %llu\n", dataflash.get_erase_size());

    // Write "Hello World!" to the first block
    char *buffer = (char*)malloc(dataflash.get_erase_size());
    sprintf(buffer, "Hello World!\n");
    dataflash.erase(0, dataflash.get_erase_size());
    dataflash.program(buffer, 0, dataflash.get_erase_size());

    // Read back what was stored
    dataflash.read(buffer, 0, dataflash.get_erase_size());
    printf("%s", buffer);

    // Deinitialize the device
    dataflash.deinit();
}
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