Intel developed the 8051 series of microcontrollers in 1980 for embedded systems. They should have been extinct by now, but they are still around and are, in fact, quite popular. The 8051 has since then been upgraded. The newer variants of the 8051 currently available in the market are more powerful, consume less power, and, most importantly, are cheaper.

It is quite logical to question their popularity if you are new to embedded systems. If you are a student who has to study the 8051 as a part of your course syllabus, you’ll notice a faint murmur run through the class every time the 8051 is being taught. Almost everyone in my class wanted to work on the fancier and much more powerful ARM series of microcontrollers.

To understand the popularity of the 8051 and the need to study it, you need to know about two crucial concepts in embedded systems; Design re-usability and system design metrics.

What is design re-usability?

There are a lot of semiconductor companies that manufacture logic devices like CPUs, microprocessors, microcontrollers, and so on. The process of development of these technologies is often time-consuming and needs a lot of investment.

Let’s say Company A invests a lot of time and money in developing a state of the art controller from the ground up. There are a lot of underlying processes that come together to make a controller — for example, designing the architecture. Once Company A has developed, tested, and released their finished product, they sell the license of the underlying technologies used to build that particular controller of theirs, to other companies. So if Company B buys this license from Company A, they don’t have to do all the work from scratch. They can just use Company A’s underlying technology to build their own customized controller.

The underlying technologies that are licensed are called Intellectual Property (IP) Cores. Using popular IP cores maintains consistency, and people like us get a lot of options to work on without experiencing drastic changes in usability. If every company had its own architecture, it would be quite difficult to learn those every time you wanted to try a new microcontroller. An excellent example of this are the Exynos chips from Samsung and the AX chips from Apple. They both use ARM IP cores.

The 8051 IP cores are free to use. The actual microcontrollers are incredibly cheap to buy. They are smaller and consume less power than 32 bit ARM cores. There is a large community of people who are familiar with the architecture. These are just some of the reasons why the 8051 is still popular.

System design metrics

When we design an embedded system, there are a few things that need consideration. It is the job of an embedded systems engineer to make sure that all of the following parameters (and more, as we will see later in this course) are considered.

Processing power

Reliability

Power consumption

Cost

Time to prototype & time to market

Maintainability

Processing Power

Based on the complexity of the software, a system requires a certain amount of computing power. It is necessary to find the right amount of processing power, not too little, and definitely not more than required.

8051s have enough variants that provide processing power from 1 MIPS (Original 8051) to 450 MIPS (Million Instructions Per Second)

Reliability

An embedded system needs to be tested and validated thoroughly. This stage usually takes time and adds to the cost.

The 8051 variants available in the market have been tested rigorously, thanks to its popularity and free of cost IP cores.

Power consumption

It is imperative to treat power as a scarce resource while designing an embedded system. You are always expected to develop a system that has just enough power to be fully operational. The life of a system’s battery depends on the power consumed by it.

Many 8051 variants have undergone modifications for low-power applications.

Costs

The cost is usually considered way before the actual designing of an embedded system even begins. The cost of the project is one of the biggest things to be considered before designing a project.

The 8051 has free IP cores, and the actual chips are inexpensive.

Time to prototype and time to market

Time equals higher costs and is usually mostly spent on implementing the core functionality in a working prototype, scaling it, and testing it. Time to market is the time required to make a system ready for marketing.

Since the 8051 has a simple architecture, its testing is easy too.

Maintainability

The ease with which a system can be maintained or modified after its commercial release. Especially by designers who were not involved in the original designing of the system.

What is the current status of the 8051 in the embedded systems world?

There are more than 20 companies out there that manufacture 8051 variants and its compatible IP cores. Generally speaking, almost all of them have modified or upgraded the 8051 in some way.

The original 8051 had 4KB of ROM and 128 bytes of RAM.

Modern variants of the 8051 have been upgraded over the years. And thye have come to include a lot of features like built-in reset timers, on-chip oscillators, self-programmable Flash ROM program memory, built-in external RAM, extra internal program storage.

The addition of communication protocols like I²C, SPI, USB, CAN or LIN bus, ZigBee and Bluetooth have profoundly impacted the growth of the 8051 in modern sensors. For example, a lot of automobiles made in the US after September 2007 were mandated to have Tire Pressure Monitoring Systems, which was implemented using sensor chips, most of which were built on 8051 IP cores.

You can also find on-chip PWM generators, analog comparators, A/D and D/A converters, extra counters, and timers, in-circuit debugging facilities, more interrupt sources, extra power-saving modes, more/less parallel ports, etc. in modern 8051 flavors. Oregano systems have an 8051 variant with an upgraded architecture for faster command execution. Furthermore, Texas Instrument’s CC3000 Bluetooth module and many WiFi routers have their TCP/IP stacks on the 8051 core.

Another exciting field where the 8051 might re-emerge is the field of IoT. Bernard Cole (editor of embedded.com) has an excellent blog post on why he thinks that the 8051 will rise against the 32 bit ARM controllers in the IoT segment.

Final verdict

In summary, the 8051 IP cores are very popular, see constant upgrades, and will be around for the time being.

As a student, you should study the 8051 to get acquainted with basic microcontroller architecture, embedded system designing, prototyping. In the meantime, you should do a few projects and test your code efficiency.

Also, note that you don’t exactly have to work on the original 8051 made by Intel, you can pick any new variant in the market. We will be working with the 89C51.

But then move on to something more advanced like the MSP430 and then eventually ARM.