Objectives
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Introduce the concept of a microcontroller and embedded system.
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Introduce the features and constraints of embedded programming.
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Introduce design paradigms, design tools, and debugging strategies.
Chapter 1 Introduction to Microcontrollers and Embedded Systems
A microcontroller is a device containing a processor, memory, input and output (I/O) pins, and other peripheral devices.
Several 8-bit microcontroller families (and their respective vendors) available as of October 2025 are listed below.
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AVR (Microchip)
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PIC (Microchip)
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S08 (NXP)
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EFM8 (Silicon Labs)
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8051 (Silicon Labs)
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STM8 (STMicroelectronics)
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TLCS (Toshiba)
Each of the microcontrollers listed above has a specific instruction set, their own set of peripheral devices and I/O pins, and are generally not interchangeable.
Remark 1.0.1. Vendor Note.
Atmel, the original producer of AVR microcontrollers, was acquired by Microchip in 2016. Many AVR manuals and datasheets still contain the Atmel name and logo. It’s possible the vendor name Atmel is still being used in this textbook.
Other “micro” devices include microcomputers and microprocessors. A microprocessor typically contains a central processing unit (CPU) but not necessarily memory, peripherals, or any I/O interface. If you have ever built a computer, this is the part that you purchase from AMD or Intel and place into the motherboard. Thermal paste is put on top to thermally link it to a heat sink, which allows heat to safely dissipate away from the sensitive electronics inside of the processor. Less expensive, less powerful microprocessors are available for tasks that are not as extensive as those needed in general purpose computing.
The advantages of using a microprocessor (as opposed to a microcontroller) include
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small footprint,
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low cost, and
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easy to customize (the user can decide what and how many peripheral devices to include).
The disadvantages of using a microprocessor include
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lack of on-chip memory,
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no peripheral functions included, and
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cannot use directly with I/O devices.
A microcomputer typically includes all the hardware of a microcontroller but is also built to run an operating system. The Raspberry Pi is a very commonly used hobbyist microcomputer. While it doesn’t have the speed or capacity as a PC or Mac, it allows the user to access the internal peripheral features of the microcontroller which allows for the implementation of different types of projects that may not be possible with a regular computer.
An embedded system is a collection of software and hardware that typically executes only one or a limited number of functions. This is in contrast to a computer, laptop, tablet, or smart phone, which is a general use machine (can be used for games, browsing the Internet, listening to music, word processing, etc.). There are many embedded systems used in the world around us, but a good rule of thumb is that an embedded system is capable of performing computations without the use of an operating system (such as Windows, Linux, macOS, iOS, etc.). Embedded systems can be found in appliances, simple watches (not necessarily smart watches), MP3 players, vending machines, and more. In these examples, a full computer would be detrimental to the operation of the device. Imagine having to boot up Windows to run a dishwasher!
