Microcontrollers have become so affordable that in many cases, it is easier to design circuits using flexible microcontroller programming than relying solely on discrete components.
For example, while you can design LED effects or emergency lights using flip-flops, timer ICs, or other discrete components like resistors, transistors, and capacitors, replacing all of these with a single microcontroller is often much more flexible, easier, and more affordable.
Powerful microcontroller boards with built-in WiFi and Bluetooth, along with substantial 4MB flash memory, are available today for under €2. This makes microcontroller projects much more cost-effective compared to implementing the same functionality with discrete components or specialized ICs. As a result, microcontrollers are ubiquitous in low-cost consumer devices like smart plugs, thermometers, and other gadgets.
Overview
Microcontrollers function like mini computers and can be programmed using simple programming or scripting languages. This creates the software that instructs the microcontroller which is called firmware.
Creating firmware does not necessarily require programming skills. Tools like ESPHome allow you to auto-generate firmware based on high-level configurations that describe the microcontroller’s behavior in abstract terms.
Often, you do not even need to create new firmware at all. Flexible, pre-made firmwares already exist for many use cases. For instance, if you want to control programmable LED strips (WS2812), WLED is a powerful and free firmware that can be uploaded to your microcontroller directly from a browser without requiring any tools or prior knowledge.
GPIOs
At the heart of each microcontroller are its GPIOs (general-purpose input/output): versatile pins that can act as either inputs or outputs:
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Output: Functions like a switch, toggling between on and off. This allows you to control devices, lights, or other components. Since GPIOs are signal pins and typically handle only 10-40mA (depending on the microcontroller), external components like MOSFETs or relays are often needed to drive higher loads.
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Input:
- Digital inputs detect high (positive voltage) or low (ground) states, enabling connection to switches, sensors, or other components.
- Analog inputs (available on some GPIOs) measure voltage levels, useful for components like potentiometers or voltage sensors.
Communication
Input and output GPIOs can also be used for communication. This is how microcontrollers connect to external devices like sensors and displays. Communication protocols like Serial, I2C, and SPI function like high-speed “morse code,” transferring data back and forth.
- For unidirectional communication (e.g., microcontroller to display), one side serves as the sender (using an output GPIO), and the other as the receiver (using an input GPIO).
- Bidirectional communication generally requires at least two GPIOs per device—one for sending (output) and another for receiving (input).
A critical factor when selecting a microcontroller board is the number of available GPIOs. Ensure the board you choose has enough GPIOs for your project. If you need additional GPIOs, you can use port extenders—external modules that add more GPIOs.
Wireless
Another form of communication involves wireless protocols like WiFi and Bluetooth. Modern microcontrollers, such as those in the ESP32 family, come equipped with integrated transmitters and receivers, making it easy to connect devices wirelessly. For example, you can control your device via a web interface on your smartphone or integrate it into home automation platforms like Home Assistant.
Wireless capabilities also enable the upload of new firmware wirelessly. This feature, called OTA (over-the-air updates), is particularly useful when your microcontroller is built into a device. With OTA, you can update the firmware remotely—fixing bugs or adding new features—without needing physical access to the microcontroller board.
Microcontrollers used in Computers and Smartphones
Here are some microcontrollers used in popular computers, notebooks, and smartphones:
| Microcontroller | Used In |
|---|---|
| Intel i3, i5, i7, i9, Xenon | Computers running Windows (Microsoft) |
| AMD Ryzen 3, 5, 7, 9, EPYC | Computers running Windows (Microsoft) |
| Apple Silicon M1, M1 Pro, M1 Max, M2 | Computers running MacOs (Apple) |
| Apple A14, A15, … Bionic | Apple iPhone Smartphones |
| Qualcom SnapDragon 4xxx, 6xxx, 7xxx, 8xxx | Android Smartphones |
| Mediatec Helio, Dimensity | Android Smartphones |
| Samsung Exynos | Android Smartphones |
| Huawai Kirin | Android Smartphones |
These microcontrollers are fundamentally no different from the microcontrollers I am discussing in this section, however they are more powerful and harder to use: after all, they are designed to run full-fledged general-purpose operating systems.
In DIY projects and to control hardware, simpler microcontrollers are used that are much cheaper (cost is often below EUR 1.00/piece) and very much easier to program.
DIY Microcontrollers
There are thousands of different microcontroller types available, yet in DIY projects, only a few microcontroller families are typically used. Sticking to popular microcontroller families for your own DIY projects is wise because they offer a rich community base of sample code, tips, and support.
Popular Microcontroller Families
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Arduino:
“Arduino” is an Italian open-source hardware and software company, not a specific microcontroller family. Arduino board designs use a variety of microprocessors and controllers. When this project began in 2005, it was state-of-the-art and made microcontrollers feasible for hobbyists. Today, however, many users still rely on Arduino boards, despite their technical obsolescence, higher cost, and lack of crucial features like wireless communications. -
ESP:
Originally, the Chinese manufacturer Espressif produced cheap but powerful microcontrollers for industrial use with built-in WiFi communications. The community adopted the ESP-01 module with the ESP8266 microcontroller in 2014, integrating it into the Arduino ecosystem. The release of the dual-core ESP32 in 2015 established it as the de-facto standard for affordable and powerful microcontrollers, outperforming Arduino boards in features and price. Subsequent Espressif releases have maintained compatibility while adding functionality. ESP microcontrollers can use Arduino code and libraries, along with thousands of additional libraries and projects designed exclusively for ESP, such as ESPHome and WLED. -
ATtiny:
These microcontrollers focus on small size (DIP packages) and extremely low energy consumption, making them ideal for battery-operated sensors. While functionally limited (e.g., slower speed, fewer GPIOs), their capabilities often suffice for simple automation tasks. However, when evaluated purely on computational power, ATtiny microcontrollers are relatively expensive, costing as much as an entry-level ESP32 C3 (€1-2). Their exceptionally low power consumption still makes them a solid choice for specialized, low-computation projects.
Raspberry Pi
Raspberry Pi computers also play an important role in DIY projects, though they are not microcontrollers. Instead, Raspberry Pi boards are mini-computers comparable to PCs. The latest Raspberry Pi 5 is fast enough to run a Linux operating system with a graphical user interface.
Compared to traditional PCs, Raspberry Pis are more affordable, compact, and energy-efficient, making them a popular choice for running servers, such as Home Assistant.
Mini-PC and Proxmox
For projects requiring more server power than a Raspberry Pi can provide, users often turn to Intel-based Mini-PCs paired with the free virtualization software Proxmox. This setup enables the running of multiple server instances in parallel, but it comes with added complexity and significantly higher energy consumption, especially when running 24/7.
If you really need to run multiple server instances or handle high-computation tasks, a Mini-PC with virtualization software like Proxmox can be a cost-effective solution. However, for simpler use cases like running Home Assistant, a Mini-PC would mostly idle, wasting energy. Given today’s high energy costs and environmental concerns, a Raspberry Pi 5 is often the most economical choice for many scenarios.
Conclusions
- Microcontroller Selection: Choosing a microcontroller family with a strong community (e.g., ESP or Arduino) ensures access to extensive resources, making troubleshooting and development much easier.
- Cost-Effectiveness: While Arduino remains popular, modern microcontrollers like the ESP32 often provide better performance and features at a fraction of the cost.
- Energy Efficiency: For low-power or battery-powered projects, consider microcontrollers like ATtiny. For servers or always-on devices, weigh the energy usage of solutions like Raspberry Pi versus Mini-PCs carefully.
- Scalability: If you anticipate needing advanced features like virtualization, start with a Raspberry Pi but plan for potential migration to a Mini-PC or Proxmox solution.
Development Boards
Development boards are ready-to-use PCBs that integrate a microcontroller with essential components such as a voltage regulator and a Serial-to-USB bridge. They simplify the process of working with microcontrollers by providing an accessible platform for programming and development.
Originals and Clones
While the microcontroller itself is manufactured by specific companies (e.g., Espressif or Atmel), development boards are produced by various vendors. These include well-known brands like Arduino, Adafruit, or Espressif, as well as less-known manufacturers who create clones.
Key Differences Between Originals and Clones
- Originals: Designed and built by reputable companies, offering high-quality components and support.
- Clones: Functionally equivalent to originals but manufactured by third parties, often at a much lower price.
Clones are usually much cheaper than originals, especially for Arduino boards.
Clones in this context are not about piracy or deception. These boards replicate functionality but not appearance. You can easily differentiate between an original board and a clone. Since the hardware designs are open source, creating clones is neither copyright infringement nor unethical.
Quality of Clones
The quality of clones varies significantly depending on the manufacturer. While some are well-built and even offer added features (e.g., integrated displays), others use cost-saving measures that may affect reliability. Here are some common issues:
| Issue | Symptom | Remarks |
|---|---|---|
| Cheap voltage regulator | Board reboots or stops working with multiple connected components | A known issue with early ESP8266 boards; most newer boards have improved. |
| Soldering issues | Short circuits due to solder drops | Rare (1 in 100), related to low-quality control in mass production. Usually evident at first use. |
| PCB quality | Hard-to-read labels | Does not affect functionality but may indicate lower-cost production. |
Tip: Consider the cost of ten units when comparing prices between originals and clones. For large-scale DIY projects, clones may offer significant savings.
Ethical Considerations
Is Buying Clones Morally Reprehensible?
Some wonder if purchasing clones undermines intellectual property or takes advantage of others’ efforts. However:
- The microcontroller chip itself is always original and purchased legitimately.
- Circuit designs for development boards are typically open source.
- Tools and firmware are community-supported, making the ecosystem robust.
Why are clones cheaper?
The cost savings often come from:
- Lean production processes.
- Fewer middlemen and distributors.
- Direct purchasing from platforms like AliExpress at wholesale prices.
In many cases, the same boards are sold on Amazon or local stores for significantly higher prices, even though they are identical to those found on global e-commerce platforms.
Conclusion
When deciding between originals and clones:
- Originals: Offer reliability and support, ideal for beginners or critical projects.
- Clones: Provide cost-effective alternatives, especially for bulk purchases or non-critical projects.
Both have their place in the DIY ecosystem, and choosing between them depends on your priorities: cost, quality, or brand trust.
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(content created Feb 15, 2024 - last updated Dec 11, 2024)