SST25 NOR Flash

NuttX provides support for SPI based NOR flashes from SST25 family Supported capacity is up to 64 Mbit (8 MB).

SST25

Standard SST25 driver can be enabled by CONFIG_MTD_SST25 option. This driver supports the capacity up to 32 Mbit (4 MB). It is possible to select the SPI mode with CONFIG_SST25_SPIMODE option and communication frequency with CONFIG_SST25_SPIFREQUENCY option.

The flash allows to simulate 512-byte large erase blocks if option CONFIG_SST25_SECTOR512 is enabled. You may also configure the flash as read only if CONFIG_SST25_READONLY is set.

The size of the flash is set automatically during the device initialization.

The flash memory has to be initialized before used. This is typically done from board support package layer during the board’s bringup phase. This operation is performed by following function.

#include <nuttx/mtd/mtd.h>

FAR struct mtd_dev_s *sst25_initialize(FAR struct spi_dev_s *dev)

SST25XX

This driver supports SST25 flashes with 64 Mbit and larger capacity. With the 64 MBit and larger parts, SST changed the write mechanism to support page write instead of byte/word write like the smaller parts. As a result, the SST25 driver is not compatible with the larger density parts, and the SST25XX driver must be used instead.

This driver is enabled by CONFIG_MTD_SST25XX option. It is possible to select the SPI mode with CONFIG_SST25XX_SPIMODE option and communication frequency with CONFIG_SST25XX_SPIFREQUENCY option.

Various manufacturers may have produced the parts. 0xBF is the manufacturer ID for the parts manufactured by SST. This is the default option set by CONFIG_SST25XX_MANUFACTURER. The same applies for memory type, the default set by CONFIG_SST25XX_MEMORY_TYPE is 0x25.

The size of the flash is set automatically during the device initialization.

The flash memory has to be initialized before used. This is typically done from board support package layer during the board’s bringup phase. This operation is performed by following function.

#include <nuttx/mtd/mtd.h>

FAR struct mtd_dev_s *sst25xx_initialize(FAR struct spi_dev_s *dev)