Serial Peripheral Interface: Difference between revisions

Revision as of 15:07, 7 August 2024

Revision as of 15:18, 16 August 2024

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SPI has four [[Logic signal|logic signals]] (which may have [[#Alternative terminology|alternative names]]):

:{| class="wikitable"

! Short<br />Name !! Long<br />Name !! Description<br />(historical terms in parens)

|-

| {{center|{{Overline|CS}}}} || {{center|Chip Select}} || [[Logic level#Active state|Active-low]] [[Chip select|chip select signal]] from main (master) to<br />enable communication with a specific sub (slave) device.

|-

| {{center|SCLK}} || {{center|Serial Clock}} || [[Clock signal]] from main (master).

|-

| {{center|MOSI}} || {{center|Main Out, Sub In<br />(master out, slave in)}} || [[Serial communication|Serial data]] from main (master), [[most-significant bit]] first.

|-

| {{center|MISO}} || {{center|Main In, Sub Out<br />(master in, slave out)}} || [[Serial communication|Serial data]] from sub (slave), most-significant bit first.

|}

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|-

! SPI mode

! Clock polarity<br />(CPOL)

! Clock phase<br />(CPHA)

!Data is shifted out on

! Data is sampled on

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** SDI, DI, DIN, SI, SDA - on sub-only devices; Various abbreviations for "Serial" "Data" "In". Connects to MOSI (or alternative names) on main

** SDO, DO, DOUT, SO - on main-only devices; Various abbreviations for "Serial" "Data" "Out". connects to MOSI (or alternative names) on sub

** COPI, PICO for "peripheral and controller",<ref name="OSHWA">[https://www.oshwa.org/a-resolution-to-redefine-spi-signal-names/ SPI; OSHWA.]</ref><ref name=":5">https://www.ti.com/lit/an/scea091a/scea091a.pdf {{Bare URL PDF|date=August 2024}}</ref> or COTI for "controller" and "target"<ref name=":1">{{Cite web |title=Serial Peripheral Interface (SPI) Devices |url=https://www.nxp.com/products/interfaces/ic-spi-i3c-interface-devices/www.nxp.com/pages/:SPI |url-status=live |archive-url=https://web.archive.org/web/20230601020101/https://www.nxp.com/products/interfaces/ic-spi-i3c-interface-devices/spi-interface-devices:SPI |archive-date=2023-06-01 |access-date=2023-07-22 |website=[[NXP]]}}</ref>

* MISO : "Master" In ← "Slave" Out. Now can be read as "Main" In "Sub" Out, or can use these alternatives:

** SOMI, MRST, SPIQ - correspond to MISO on both main and sub devices, connects to each other