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Flavors of SPI: Emerging Protocol in Automotive


SPI interface is emerging as a popular choice in automotive applications ranging from sensors, display console, navigation systems, booting through SPI Flash and many more. SPI low pin count and configurable clock rate facilitate the requirements of the emerging automotive applications.

Synchronous Serial Peripheral bus (SPI) allows synchronous serial communication between a controller and peripheral devices. It enables full duplex or half duplex communication with continuous streaming of data communicated between master (controller) and slave (peripheral devices). It can be configured in multiple architectures ranging from single master-single slave to multi master-multi slave systems. The master will always be the controller of bus activity on the interface between the connecting components. The serial protocol supports a low pin count interface that consists of Chip Select, Clock, and Data out from controller to peripheral device and Data into controller pins from peripheral device. The low pin count interface based on selected configuration supports various vendor specific modes mentioned below.


Flavors of SPI

Motorola Serial Peripheral Interface (SPI)

Serial Peripheral Interface (SPI), developed by Motorola, allows duplex communication on a four-wire interface with distinctive features such as programmable serial clock polarity and phase.


  • Programmable clock polarity and phase
  • Programmable bit and byte endianness
  • Transfer modes such as TX only, RX only and TX-RX

Texas Instruments Synchronous Serial Protocol (SSP)

Synchronous Serial Protocol (SSP), developed by Texas Instruments, allows continuous streaming of data transfer by asserting frame indicators. It is a four-wire interface, with slave select also used as next frame indicator for continuous data stream.


  • Data frame indicator
  • Transfer modes such as TX only, RX only and TX-RX

National Semiconductor Microwire (UWIRE)

Microwire (UWIRE) or popularly known as 3 wire interface, developed by National Semiconductor, allows half-duplex communication between devices. Data communication either consists of control word followed by continuous data stream (sequential mode) or stream of control word followed by data word (Non-sequential mode).


  • Sequential and non-sequential transfer
  • Transfer modes such as TX only and RX only
  • Handshaking support

Synopsys VC VIP for SPI

Synopsys VC VIP for SPI provides coverage driven exhaustive directed and random sequences, and run time configurable options to select among multiple modes to cater to a wide range of industry requirements. The VIP, based on next-generation native System Verilog and UVM architecture, provides built in verification plans and coverage for accelerated verification closure. VIP also supports integrated Verdi® Protocol Analyzer for advanced debug capabilities.

VC VIP for SPI supports SPI serial bus as well as SPI Flash including Dual, Quad, and Octal lane based NAND/NOR Flash models for vendors like Micron, Cypress, Spansion, Macronix, Winbond, and ISSI etc. Stay tuned to this page for upcoming blogs on SPI Flash.

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