spidev library usage in Raspberry Pi - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the spidev library in Raspberry Pi?

The spidev library allows Python programs to communicate with SPI devices connected to the Raspberry Pi. It provides an interface to send and receive data over the SPI bus.

beginner

How do you open an SPI connection using spidev?

You create an instance of spidev.SpiDev() and call its open(bus, device) method, where bus is the SPI bus number (usually 0) and device is the chip select (CS) line (usually 0 or 1).

intermediate

What does the xfer2() method do in spidev?

The xfer2() method sends a list of bytes to the SPI device and simultaneously receives a list of bytes back. It performs a full-duplex SPI transfer.

intermediate

How can you set the SPI speed using spidev?

You set the max_speed_hz attribute of the SpiDev object to the desired speed in hertz. For example, spi.max_speed_hz = 500000 sets the speed to 500 kHz.

beginner

Why is it important to close the SPI connection in spidev?

Closing the SPI connection with spi.close() frees the SPI device and system resources. It helps avoid conflicts if other programs want to use SPI later.

Which method opens the SPI device in spidev?

A start(bus, device)

B open(bus, device)

C connect(bus, device)

D init(bus, device)

The open(bus, device) method is used to open the SPI device on the specified bus and chip select.

What type of data does xfer2() send and receive?

A List of bytes

B String

C Integer

D Boolean

xfer2() sends and receives a list of bytes for SPI communication.

How do you set the SPI clock speed in spidev?

A spi.max_speed_hz = value

B spi.speed = value

C spi.clock = value

D spi.set_speed(value)

The max_speed_hz attribute sets the SPI clock speed in hertz.

Which of these is NOT a typical SPI bus number on Raspberry Pi?

A 0

B 2

C 3

D 1

Raspberry Pi usually has SPI buses 0 and 1; bus 3 is not standard.

Why should you call spi.close() after SPI communication?

A To increase data transfer size

B To speed up the SPI bus

C To reset the SPI device

D To free system resources and avoid conflicts

Closing the SPI connection frees resources and prevents conflicts with other programs.

Explain how to set up and use the spidev library to send data to an SPI device on Raspberry Pi.

Think about the steps from starting communication to ending it.

Describe the role of the xfer2() method in SPI communication using spidev.

Focus on what happens during data transfer.