Summary of Basics of the SPI Communication Protocol
This article introduces communication protocols in electronics, focusing on SPI as the first of three common methods (SPI, I2C, UART). It explains that SPI uses a master-slave relationship, allows continuous data streams without packet interruption, and is ideal for low-speed microcontroller-to-sensor communication. While slower than USB or WiFi, SPI requires fewer resources and hardware components.
Parts used in the SPI Communication Project:
- Microcontroller
- Sensors
- Displays
- Memory chips
- SD card modules
- RFID card reader modules
- 2.4 GHz wireless transmitter/receivers
When you connect a microcontroller to a sensor, display, or other module, do you ever think about how the two devices talk to each other? What exactly are they saying? How are they able to understand each other?
Communication between electronics is like communication between humans. Both sides need to speak the same language. In electronics, these languages are called communication protocols. Luckily for us, there are only a few communication protocols we need to know when building most DIY electronics projects. In this series of articles, we will discuss the basics of the three most common protocols: Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I2C), and Universal Asynchronous Receiver/Transmitter (UART) driven communication.
First, we’ll begin with some basic concepts about electronic communication, then explain in detail how SPI works. In the next article, we’ll discuss UART driven communication, and in the third article, we’ll dive into I2C.
SPI, I2C, and UART are quite a bit slower than protocols like USB, ethernet, Bluetooth, and WiFi, but they are a lot more simple and use less hardware and system resources. SPI, I2C, and UART are ideal for communication between microcontrollers and between microcontrollers and sensors where large amounts of high speed data don’t need to be transferred.
SPI is a common communication protocol used by many different modules. For example, SD card modules, RFID card reader modules, and 2.4 GHz wireless transmitter/receivers all use SPI to communicate with the microcontroller.
One unique benefit of SPI is the fact that data can be transferred without interruption. Any number of bits can be sent or received in a continuous stream. With I2C and UART, data is sent in packets, limited to a specific number of bits. Start and stop conditions define the beginning and end of each packet, so the data is interrupted during transmission.
Devices communicating via SPI are in a master-slave relationship. The master is the controlling device (usually a microcontroller), while the slave (usually a sensor, display, or memory chip) takes instruction from the master. The simplest configuration of SPI is a single master, single slave system, but one master can control more than one slave (more on this below).
For More Details: Basics of the SPI Communication Protocol
- What are the three most common communication protocols discussed?
The three protocols are Serial Peripheral Interface, Inter-Integrated Circuit, and Universal Asynchronous Receiver/Transmitter. - How does SPI compare to USB or WiFi in terms of speed?
SPI is quite a bit slower than protocols like USB, ethernet, Bluetooth, and WiFi. - Why might a builder choose SPI over other high-speed protocols?
SPI is more simple, uses less hardware, and consumes fewer system resources. - Can SPI transfer data in a continuous stream?
Yes, data can be transferred without interruption in a continuous stream. - How do I2C and UART differ from SPI regarding data transmission?
I2C and UART send data in packets limited to specific bits with start and stop conditions. - What is the relationship between devices communicating via SPI?
Devices communicate in a master-slave relationship where the master controls the slave. - Which device usually acts as the master in an SPI setup?
The microcontroller is usually the controlling device acting as the master. - Is it possible for one master to control multiple slaves?
Yes, one master can control more than one slave.
