SPI with external devices (sensors, displays) in Embedded C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does SPI stand for and what is its main purpose?

SPI stands for Serial Peripheral Interface. It is a communication protocol used to send data between a microcontroller and external devices like sensors or displays quickly and efficiently.

beginner

Name the four main signals used in SPI communication.

The four main SPI signals are:<br>1. MOSI (Master Out Slave In) - data from master to slave<br>2. MISO (Master In Slave Out) - data from slave to master<br>3. SCLK (Serial Clock) - clock signal from master<br>4. SS (Slave Select) - selects which slave device to communicate with

beginner

How does the master device control communication in SPI?

The master device controls communication by generating the clock signal (SCLK) and selecting the slave device using the Slave Select (SS) line. It sends data on MOSI and reads data on MISO.

intermediate

Why is SPI preferred for connecting sensors and displays in embedded systems?

SPI is preferred because it is fast, simple, and supports full-duplex communication. It uses fewer wires than parallel interfaces and can connect multiple devices using separate SS lines.

beginner

What is the role of the Slave Select (SS) line in SPI communication?

The Slave Select (SS) line tells a specific slave device to listen and respond to the master. When SS is low (active), the slave is selected; when high, the slave ignores the SPI bus.

Which SPI signal carries data from the master to the slave?

A MOSI

B MISO

C SCLK

D SS

MOSI stands for Master Out Slave In, so it carries data from the master to the slave.

What does the master device generate in SPI communication?

A Only clock signal

B Only data signals

C Only Slave Select

D Clock signal and Slave Select

The master generates both the clock signal (SCLK) and the Slave Select (SS) to control communication.

In SPI, what happens when the Slave Select (SS) line is high?

A Slave device ignores communication

B Slave device is selected and active

C Master stops sending clock

D Data is sent on MISO

When SS is high, the slave device ignores the SPI bus and does not communicate.

Which of these is NOT a typical use of SPI?

A Connecting sensors

B Connecting displays

C Connecting to the internet

D Connecting memory chips

SPI is not used for internet connections; it is used for short-distance device communication like sensors and displays.

What type of communication does SPI support?

A Half-duplex only

B Full-duplex

C Simplex only

D No data transfer

SPI supports full-duplex communication, meaning data can be sent and received at the same time.

Explain how SPI communication works between a microcontroller and a sensor.

Think about who controls the clock and how data flows both ways.

Describe the role of each SPI signal line and why they are important.

Focus on what each wire does during communication.