spidev library usage in Raspberry Pi - Mini Project: Build & Apply

Using the spidev Library to Communicate with SPI Devices on Raspberry Pi

📖 Scenario: You have a Raspberry Pi connected to an SPI device like an ADC or a sensor. You want to send and receive data using the SPI protocol.

🎯 Goal: Build a simple Python program using the spidev library to open the SPI bus, send data, receive data, and close the connection.

📋 What You'll Learn

Create an instance of the spidev.SpiDev() class

Open SPI bus 0, device 0 using open(0, 0)

Set SPI max speed to 1 MHz using max_speed_hz

Send a list of bytes [0x01, 0x02, 0x03] using xfer2()

Print the response received from the SPI device

Close the SPI connection using close()

💡 Why This Matters

🌍 Real World

SPI devices like sensors, ADCs, and displays often connect to Raspberry Pi using SPI. This project shows how to communicate with them.

💼 Career

Embedded systems and IoT developers frequently use SPI communication. Knowing spidev is useful for hardware interfacing jobs.

1

Import spidev and create SPI object

Import the spidev library and create an SPI object called spi using spidev.SpiDev().

Raspberry Pi

# Import spidev and create spi object
# Your code here

Hint

Use import spidev to bring in the library. Then create the SPI object with spi = spidev.SpiDev().

2

Open SPI bus and set speed

Use the spi object to open SPI bus 0, device 0 with open(0, 0). Then set spi.max_speed_hz to 1000000 (1 MHz).

Raspberry Pi

import spidev
spi = spidev.SpiDev()
# Open SPI bus 0, device 0
# Set max speed to 1 MHz
# Your code here

Hint

Use spi.open(0, 0) to open bus 0, device 0. Then set spi.max_speed_hz = 1000000 to set speed.

3

Send and receive data using xfer2

Send the list of bytes [0x01, 0x02, 0x03] using spi.xfer2([0x01, 0x02, 0x03]) and save the response in a variable called response.

Raspberry Pi

import spidev
spi = spidev.SpiDev()
spi.open(0, 0)
spi.max_speed_hz = 1000000
# Send bytes [0x01, 0x02, 0x03] and save response
# Your code here

Hint

Use spi.xfer2() to send and receive data. Save the result in response.

4

Print the response and close SPI

Print the response variable using print(response). Then close the SPI connection with spi.close().

Raspberry Pi

import spidev
spi = spidev.SpiDev()
spi.open(0, 0)
spi.max_speed_hz = 1000000
response = spi.xfer2([0x01, 0x02, 0x03])
# Print the response
# Close the SPI connection
# Your code here

Hint

Use print(response) to show the data received. Then call spi.close() to end communication.

The actual response may vary depending on your SPI device. For testing, assume it returns [0, 0, 0].