Editing Serial Peripheral Interface (section)

{{Short description|Synchronous serial communication interface}}
{{Cleanup rewrite|[[WP:NOTTEXTBOOK|it reads like a guide or textbook]]|article|date=March 2021}}
{{Infobox connector <!-- NOTE: Not a perfect template match, but good enough for now -->
| name = Serial Peripheral Interface (SPI)
| type = [[Serial communication]] [[Bus (computing)|bus]]
| designer = [[Motorola]]
| data_style = [[Full-duplex]] [[serial communication|serial]]
| daisy_chain = [[#Daisy chain configuration|Depends]] on devices
| manufacturer = various
| data_devices = [[#Multidrop configuration|Multidrop]] limited by slave selects. [[#Daisy chain configuration|Daisy chaining]] unlimited.
| data_bit_width = 1 bit (bidirectional)
| high_freq = yes
| pin_custom1_name = MOSI
| pin_name_custom1 = Master Out Slave In
| pin_name_custom2 = Master In Slave Out
| pin_custom2_name = MISO
| pin_custom3_name = SCLK
| pin_custom4_name = {{Overline|SS}}
| pin_name_custom3 = Serial Clock
| pin_name_custom4 = [[Slave Select]] (one or more)
| pinout_notes = (pins may have [[#Alternative terminology|alternative names]])
| maximum_voltage = Unspecified
| maximum_current = Unspecified
| physical_connector = Unspecified
| design_date = Around early 1980s{{NoteTag|The earliest definitive mention of a "Serial Peripheral Interface" in bitsavers archives of Motorola manuals is from 1983 (see {{slink||Original definition}}). While some sources on the web allege that Motorola introduced SPI when 68000 was introduced in 1979, however many of those appear to be [[citogenesis]] or speculation, and Motorola's 1983 68000 manual has no mention of "Serial Peripheral Interface", so the alleged 1979 date doesn't seem to be reliable information. Please only add a specific design_date if you have a definitive source from Motorola around then.}}
}}

'''Serial Peripheral Interface''' ('''SPI''') is a <!--DO NOT ITALICIZE; CONSIDERED ANGLICIZED-->[[de facto standard]] (with many [[#Variations|variants]]) for [[Comparison of synchronous and asynchronous signalling|synchronous]] [[serial communication]], used primarily in [[embedded systems]] for short-distance [[wired communication]] between [[integrated circuits]].

SPI follows a [[master–slave (technology)|master–slave architecture]],<ref name=":0">{{Cite web |last=Stoicescu |first=Alin |date=2018 |title=Getting Started with SPI |url=https://ww1.microchip.com/downloads/en/Appnotes/TB3215-Getting-Started-with-SPI-90003215A.pdf |url-status=live |website=[[Microchip]]}}</ref> where a master device [[Signaling (telecommunications)|orchestrates communication]] with one or more slave devices by driving the [[clock signal|clock]] and [[chip select]] signals. Some devices support changing master and slave roles on the fly.

[[Motorola]]'s original specification (from the early 1980s) uses four [[logic signal]]s, aka lines or wires, to support [[full duplex]] communication. It is sometimes called a ''four-wire'' [[serial bus]] to contrast with [[Serial Peripheral Interface#Three-wire|three-wire]] variants which are [[half duplex]], and with the ''two-wire'' [[I²C]] and [[1-Wire]] serial buses.

Typical [[#Applications|applications]] include interfacing [[microcontrollers]] with peripheral chips for [[Secure Digital]] cards, [[liquid crystal display]]s, [[analog-to-digital]] and [[digital-to-analog converters]], [[Flash memory#Serial flash|flash]] and [[EEPROM#Serial bus devices|EEPROM]] memory, and various communication chips.

Although SPI is a synchronous serial interface,<ref>{{cite web |url= https://digital.ni.com/public.nsf/allkb/862567530005F09C862566BE004E469D |title= What is Serial Synchronous Interface (SSI)? |access-date= 2015-01-28 }}</ref> it is different from [[Synchronous Serial Interface]] (SSI). SSI employs [[differential signaling]] and provides only a single [[simplex communication]] channel.