8051 Microcontroller Course

Course content

Why do we have to use the 8051? Isn’t it too old?

Why do we still use the 8051 is a very common question. Let’s see why it remains so popular even 35+ years after its launch.

8051 Architecture – In-depth explanation using old and modern variants

A lot of classes on 8051 will speed through the architecture of the microcontroller by just highlighting the components. But it always leaves students wanting more. In this post, we will truly simplify every component of the 8051’s architecture and its block diagram. In addition to that, we will also compare it with a very modern version of a microcontroller built using the 8051 IP core. This will help you understand the development that has taken place over the years and the demands of the market.

AT89C51 Pins – Ultimate guide to the 8051’s pin configuration

Atmel’s AT89C51 has 40 pins. Understanding the function of each pin will give you a brief idea about the microcontrollers capabilities.

Ports of 8051 – Functions and specifications of the four I/O ports

The pins of the 8051 are divided into four ports. Port 0, 1, 2 and 3. In this post we will look at the comprising pins in each port and their functions.

8051 Memory Organization – ROM and RAM Structure

The 8051 has a tiny amount of on-chip memory to store programs and data. This memory is divided into RAM and ROM and has a certain layout. Let’s study this layout and take a detailed dive into the organization of on-chip memory in the 8051.

Special Function Registers of 8051 (SFR)

Registers are bae. Truly. As you progress in your embedded systems journey, you will realize that registers allow you a lot of room to improve your code. The 8051 has an entire area dedicated to Special Function Registers. This is the equivalent of the first time man found out about cup-holders in cars. Let’s break down the functions of all these registers and understand their importance.

Addressing modes in 8051 microcontroller

All processors and controllers can access data stored in the memory using instructions or commands. However, the method in which they access this data varies on the addressing modes that they are capable of using. So, in short, data access has many types, known as addressing modes. Let’s take a look at the addressing modes available in 8051.

Data Transfer instructions in 8051

Moving data around is an elementary function of any processing unit. Here are all the instructions that we use to move data in the 8051 microcontroller. Pay special attention to the flags section, you might notice a pattern that would need remembering.

Arithmetic instructions in 8051 – with examples

Next up, we’ll take a look at the arithmetic instructions available to us in 8051. Keep an eye out for the subtraction instructions. The 2’s complement aspect can make them seem confusing at first.

Logical instructions in 8051 – with example codes

The third category of the instruction set is the bunch of instructions that are responsible for implementing logic and helping the ALU perform logical operations.

Boolean (bitwise) instructions in 8051 for bit manipulation

Bit-wise operations are an amazing feature that really helps you cut the overhead processing from your programs. Instead of performing operations on an entire byte of data, you can just pick out a bit and say “EXOR this bit in particular”. Now that we have seen all the instructions in 8051, let’s summarize the ones that can perform bit-wise operations in this post.

Branching Instructions in 8051

The final category of the instruction set of the 8051 that we’ll study is the one on branching instructions. These instructions help you jump around in the memory spaces. They are essential for executing subroutines and servicing interrupt requests. Let’s check them out.

Interrupts in 8051 microcontroller – With examples

The world of microcontrollers would be dull and gray without interrupts. The ability to pause an existing task to address a task of higher priority is simply elegant! Let’s take a look at how interrupts are implemented in the 8051 microcontroller with a nifty analogy and a few useful examples.

Timers and Counters in 8051

This is another crucial concept that you’ll be needing in your embedded systems learning journey. Timing an event and counting the number of events are both done via a network of interconnected registers inside the 8051. Let’s break the entire system down and understand each bit piece by piece.

8051 external memory interfacing guide: RAM and ROM

The 8051, in addition to on-chip memory, can also be connected to external memory chips to increase its storage capacity. This is a complete guide to interface external ROM (program or data storage) and external RAM (data storage) with the 8051 with detailed steps and explanation.

Set up Keil c51 for 8051 microcontroller simulations – A step by step guide

All embedded development projects need a powerful IDE. A tool that combines several operations in one powerful suite to give you complete final files and also allows you to burn them to your uC. In addition to that, it also allows you to simulate and debug code. Let’s check out Keil’s C-51 IDE for working with 8051 variants.

Serial communication with UART in 8051 – Simple in-depth explanation

You must have heard the acronym UART thrown around in a lot of embedded systems related classes or groups or job postings. Turns out, it’s actually quite a simple method to communicate serially. However, there are a few features that can be tweaked according to our needs. And to avail these features, we use a bunch of registers. Let’s take a look at how the UART is implemented in 8051 and which registers are deployed to control serial communication via the UART circuitry.

Interfacing of 8051 with 8255 Programmable Peripheral Interface

The 8255 is a powerful IC known as a Programmable Peripheral Interface that you can use to expand the number of I/O ports in your 8051 based embedded system. Here’s a tutorial on how to do it.

Interfacing 8051 with ADC 0808 – Stepwise tutorial

External ADCs are sparsely used in modern embedded systems. However, to understand the working of built-in ADCs and even on the off-chance that you ever have to use one, this project on interfacing the external 0808 ADC IC with the 8051 can be extremely helpful. Dive in!

LED interfacing with 8051 – Direct and with 8255

Blinking an LED is the “Hello World” of microcontroller projects. In this post, we will interface a single LED, and then multiple LEDs using direct interfacing with 8051. We’ve also added a section on interfacing multiple LEDs using 8255 that you can refer to once you are comfortable with the working of the 8255 PPI.

LED and switch interfacing with 8051 – Including switch debouncing

A majority of the 8051 projects that we will be covering in this course deal with outputs. This one deals with inputs. To be precise, with the switch interfacing, we intend to demonstrate how a control unit (like the switch) can be used as an input device to control some other peripheral connected to the 8051. It’s an interesting exercise. Check it out!

LCD interfacing with 8051 – 8-bit, 4-bit mode, and with 8255 PPI

Another classic project to understand the working of the 8051. The LCD is a nifty device that you can use to display pretty much any kind of information. In this project, we will interface the 16×2 display using all the different possible methods. 4-bit mode for when you want economical pin usage, 8-bit mode for when you want the best performance, and with the 8255 PPI for when you want a bunch of extra peripheral in your project.

Seven segment interfacing with 8051 – Single and Quad module

Seven-segment displays are cooler than LCDs if you want to display some readings or numbers. Have a go at interfacing them with your 8051 to give your project a visual uplift. In this project, we will interface a single as well as a quad seven-segment module with the 8051 uC.

Servo Motor Interfacing with 8051 – Simple tutorial

A complete tutorial with easy to follow steps on connecting a servo motor to an 8051. We’ll learn about servo motors, their interfacing with an 8051, and then the coding to control it all. We’ll code this using both assembly as well as embedded C.

Stepper Motor Interfacing with 8051 – Simple tutorial

A complete tutorial with easy to follow steps on connecting a stepper motor to an 8051. We’ll learn about stepper motors, their interfacing with an 8051, and then the coding to control it all. We’ll code this using both assembly as well as embedded C.

DC motor interfacing with 8051 using L293D and L298N

Apart from servos and stepper motors, the third most common type of motor is the DC motor. Let’s learn everything about it and especially focus on motor driver ICs like the L293D and L298N. We will learn how to control the direction of rotation of DC motors. Additionally, we will use the 8051 to generate PWM signals to control the speed of the DC motors too.

Interfacing 8051 with relays to drive high power peripherals

Relays open up an entire world of real-life practical applications with the microcontroller. You can use these nifty little devices in your projects to control high load devices like fans and lights. Set this up in your home, control your devices like a magician, and get those pesky neighbours off your back who always asked you if you were a real “engineer”. This will show ’em!

Interfacing 4×4 Keypad matrix with 8051 microcontroller

An easy to understand stepwise guide on interfacing a 4×4 keypad matrix with an 8051 and using it as a calculator. With interfacing diagram and C code.

Bluetooth (HC-05) interfacing with 8051 with practical application

Okay, now you know how to confuse your neighbours with relays. Great! But take the leap and get this HC-05 Bluetooth module interfaced with your 8051 and see their jaws drop as you control everything from a touch of your smartphone. A Bluetooth module establishes an easy-to-use wireless feature to your project. The applications are myriad. Check out the tutorial and get tinkering!

8051 – Power Down and Idle mode – Comparative Study

You might have or will read it a million times and you might as well as read it here one more time, embedded systems need to be power efficient. A lot of your work as an engineer is to make sure you are able to achieve your tasks with your system using the least amount of power necessary. A lot of modern processors and SoCs come with immaculate low power options. The 8051 has some modes that can help you save power too. And in our opinion, they offer a great insight into a concept that will keep getting more complex as you progress towards more powerful controllers. In this post, we will learn about the two low power operation options offered by the 8051, their features, and how to activate/exit them. More importantly, we will also compare the OG 8051 with modern variants that have improved low power capabilities.

8051 Microcontroller MCQ | Quiz | Interview Questions

This preliminary 8051 quiz covers all the major concepts that you’re expected to be familiar with and have learned in this free 8051 course. Clear this and you’ll be eligible to take the final certification test.

More details

New posts are still being added to this course. 

What will you learn in this course?

  • Basic concepts of microcontrollers and their essential functionalities.
  • Differentiate between a microprocessor and a microcontroller
  • Learn and set up workspace using Keil to program microcontrollers
  • Study on microcontroller on-chip peripherals.
  • Ability to read instruction set documentation and understand its implementation and execution.
  • Interfacing of common peripherals like keyboard, motors, and display screens.

Are there any software or hardware requirements for this course?

Yes. We will be using Keil C51 for simulating our assembly language programs. It is a very powerful tool that allows us to check for flag status, changes in memory locations, register contents, and enables debugging of our code.

Generally, we would advise you to get a physical 8051 learning kit (like this one or this one). However, looking at the bigger picture in terms of our embedded systems track, we would advise that you save your money. Instead, learn the basics of microcontrollers in this course and invest in a good development kit when you begin the course on the ARM Cortex M processor.

Please note that Atmel’s AT89C51 is the 8051 variant we will be using in this course. Appropriate notes are presented wherever applicable to help you understand how modern variants differ from the older ones.

What is the target of this course?

This course is part of our tracks in Embedded Systems, IoT, and Robotics. We have designed these tracks and their constituent courses (like this one) to equip learners with the basic requirements of entry-level jobs or internships in the respective fields. Head over to the pages of any of these tracks to get more information.

Are there any pre-requisites for this course?

How many quizzes are there in this course?


I would like to suggest some topics to be covered, how can I do that?

You can visit the contact page linked in the footer of this webpage. Just select “Suggest Topics” from the subject dropdown menu of the form, mention the course and why you think your suggestion makes sense to be part of the curriculum.