wiring spi bus

SPI: clock, data direction and chip select

Connect a host to a four-wire SPI peripheral without crossing the data roles.

Applies to: Conventional four-wire, active-low-CS SPI. Three-wire, daisy-chain and device-specific interfaces need their own diagrams.

When to use it

Using supported displays, memory, ADCs or radio/NFC frontends.

Why it works this way

A shared clock times the transfer, and chip select identifies the active peripheral.

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Connection reference

Mode	CPOL	CPHA
0	0	0
1	0	1
2	1	0
3	1	1

Make the connection

1. Match I/O levels, SPI mode, bit order and maximum clock to the peripheral datasheet.
2. Check that shared MISO devices release the line when deselected.
3. Start with short wires and a conservative clock.

Check before powering

• SDI/SDO labels are local to the device. Read each signal direction.
• Supply wiring and optional IRQ/reset signals are additional to the four SPI signals.

Matching module references

This is a general interface guide; match your own hardware documentation.

Sources & review

Source documents inspected; independent electrical and bench review pending. Reviewed 2026-09-27.

• Analog Devices: Introduction to SPI Interface — Interface, signal direction and CPOL/CPHA table; checked 2026-09-27

Original writing and diagram by Kal / Valleytech Solutions, CC BY 4.0. Manufacturer artwork and documentation retain their own rights.

CC BY 4.0 · SHA-256: 5232f621f0b93104e041b3032a1f339bf244e7dc721a7cf8b7b80a885e3daa02

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