How to Use SPI on Raspberry Pi Pico: Simple Guide

To use SPI on Raspberry Pi Pico, import the machine module and create an SPI object with the correct pins. Then use methods like write() and read() to send and receive data over SPI.

Syntax

To use SPI on Raspberry Pi Pico, you first import the machine module. Then create an SPI object with machine.SPI(), specifying the SPI bus ID and pins for sck (clock), mosi (master out), and miso (master in). Use write() to send data and read() to receive data.

• SPI(id, sck, mosi, miso): Creates SPI interface on given pins.
• write(bytes): Sends bytes to SPI device.
• read(nbytes): Reads bytes from SPI device.

python

from machine import Pin, SPI

spi = SPI(0, sck=Pin(18), mosi=Pin(19), miso=Pin(16))
spi.write(b'hello')
data = spi.read(5)

Example

This example shows how to send and receive 5 bytes over SPI on Raspberry Pi Pico. It initializes SPI bus 0 with pins 18, 19, and 16, sends the bytes for 'hello', then reads 5 bytes back.

python

from machine import Pin, SPI
import time

spi = SPI(0, sck=Pin(18), mosi=Pin(19), miso=Pin(16))

# Send bytes
spi.write(b'hello')

# Small delay
time.sleep(0.1)

# Read 5 bytes
received = spi.read(5)

print('Received:', received)

Output

Received: b'\x00\x00\x00\x00\x00'

Common Pitfalls

Common mistakes when using SPI on Raspberry Pi Pico include:

• Not setting the correct pins for sck, mosi, and miso.
• Forgetting to initialize the SPI bus before use.
• Not matching the SPI mode and speed with the connected device.
• Assuming read() returns meaningful data without the device sending it.

Always check your wiring and device datasheet for correct SPI settings.

python

from machine import Pin, SPI

# Wrong: missing miso pin
spi_wrong = SPI(0, sck=Pin(18), mosi=Pin(19))  # This may cause errors

# Right: specify all pins
spi_right = SPI(0, sck=Pin(18), mosi=Pin(19), miso=Pin(16))

Quick Reference

Function	Description
SPI(id, sck, mosi, miso)	Create SPI bus with specified pins
write(bytes)	Send bytes to SPI device
read(nbytes)	Read bytes from SPI device
deinit()	Turn off SPI bus when done

Key Takeaways

Create SPI object with correct pins using machine.SPI on Raspberry Pi Pico.

Use write() to send and read() to receive data over SPI.

Always check wiring and device SPI mode to avoid communication errors.

Specify all required pins: sck, mosi, and miso for proper SPI setup.

Deinitialize SPI with deinit() when finished to free resources.