SPIFlash

SPIFlash is a type of non-volatile NOR flash memory designed to be accessed over a serial SPI (Serial Peripheral Interface) bus. It is commonly used to store firmware, configuration data, and other persistent information in embedded and consumer electronics. SPIFlash devices are valued for their small pin count, low power consumption, and ease of integration into microcontroller-based systems. Many devices also support higher-throughput Quad SPI modes to increase data transfer rates.

The standard interface uses signals such as Chip Select (CS), Clock (CLK), Master In Slave Out (MISO), and Master Out Slave In (MOSI). In addition to these, some devices expose optional WP (write-protect) and HOLD pins. Communication relies on a command set that includes read, fast read, write enable, page program, sector erase, block erase, chip erase, and status register read. Writes are typically performed on a page basis, and erasures are done on larger blocks or sectors. Before programming, a write-enable command is required, and devices indicate busy status during operations.

SPIFlash memory is organized into an array with subsidiary structures such as pages, sectors, and blocks. A common page size is 256 bytes, with sectors ranging from a few kilobytes to several kilobytes and blocks sized accordingly. Data can be read quickly, and with Quad SPI it is possible to achieve higher sustained throughput. Endurance is finite, typically tens of thousands to hundreds of thousands of erase/program cycles per sector, and data retention is typically many years at room temperature.

Common applications include firmware storage for microcontrollers, boot memories, and compact data storage in embedded systems. Manufactures include several major semiconductor suppliers, offering a range of densities from kilobits to gigabits and various protective and security features.