There are many microcontrollers and boards available for DIY projects, all with their individual strengths and shortcomings. In this section here is some guidance for selecting the best microcontroller type for a given task.
Arduino
Arduinos surfaced in 2005 and started to open up microcontrollers to hobbyists and DIY makers. Arduinos are open-source board designs using a variety of microcontrollers. They are simple to program, and ArduinoIDE is a free and pragmatic coding editor. Also, given the long time that Arduinos are around, you find plenty of tutorials and code examples. In the past, Arduinos have therefore been the #1 choice for beginners. This has changed a bit, though.
Considerations
If you’d think about using an Arduino, here are some thoughts:
- Expensive: Original Arduinos are hugely overpriced. Since their board design is open-source, there are plenty of cheap clones available from Chinese companies at AliExpress. Often, they cost less than 10% of what you’d invest for an original board.
- Slow: Many Arduino boards use outdated and slow ATmel microcontrollers. They work for simple tasks but are very slow when compared to other microcontrollers and boards.
- No WiFi: Most Arduinos come with no wireless technology built-in. They can serve as stand-alone solutions but need expensive add-ons if you’d like to control them remotely or via your smartphone.
- Compatibility: While there are many free tutorials and resources for Arduinos, their once famous compatibility has faded away once Arduino started to add new models with different designs. Today, when you purchase one of the latest Arduino boards, you may run into frustrating compatibility issues, and code designed for the early Arduinos may not work on the newer ones.
- Memory: Most Arduinos come with very little memory. They work fine at first, but once your projects (and ideas) grow larger, you run into memory issues, your sketches won’t compile, and/or the board becomes unstable.
- Power: most Ardunios are 5V devices, cannot use 3.3V peripherals, and are not especially power-efficient. Battery-operated projects may not last too long. Most modern microcontrollers (like the ESP32 family) are 3.3V operated so you can power them directly off a LiFePo4 battery. They can be powered from 5V as well (boards come with integrated voltage regulators) and then support both 3.3V and 5V peripherals: their GPIOs are 5V tolerant.
In a nutshell, if you today think about onboarding the microcontroller hobby, look right away into the ESP32 family of microcontrollers, and use platformio (or even better yet, ESPHome) rather than the stale ArduinoIDE.
Most example code runs equally well on ESP32 microcontrollers and often just requires some adjustments to the GPIO pin numbers.
Recommendations
If you are determined to use an Arduino, get two or three cheap Arduino Nano Clones (avoid the heavily overpriced originals): Arduino Nano Clones are reasonably priced, provide a lot of GPIOs to play with, have a small form factor, and are breadboard-friendly. They are also compatible to most of the Arduino examples out there for a worry-free experience.
Arduino Uno is completely outdated, whereas newer boards such as Arduino Every, Arduino Nano ESP32, Arduino Uno R4, and others lack compatibility and ease-of-use: they often no longer “just work” and require extra configuration and code adjustments.
ESP32
Espressifs line of ESP32 microcontrollers today is the best choice for general purpose microcontroller projects:
They are cheap (they are not exclusively produced for hobbyists but are a smart home industry standard, often found inside commercial smart devices - mass production drops cost). They support WiFi out-of-the-box (most models also Bluetooth), today typically come with 16MB flash memory, and can be used with ArduinoIDE and platformio.
ESP32 are insanely fast, many models using dual core concepts. They also come with RTOS (real time operating system) built-in, so advanced programmers can easily create true multi-tasking firmware. They also feature efficient deep sleep modes and a low-power real time clock, making this microcontroller suited for battery- or solar-operated devices.
ESP32 have been around since 2016: the number of examples and tutorials is comparable to Arduino.
One great advantage of ESP32 microcontrollers is that they can be used with ESPHome (a much easier-to-use programming concept than writing C++ code), and integrate with Home Assistant.
Recommendations
For a most worry-free experience, stick to the original ESP32 microcontrollers (also called ESP32S, WROOM, or WROVER): they have been around for the longest time and provide the best compatibility and most examples.
Here are some other ESP32 models worth looking at:
- Super Small - ESP32-C3: If you are looking for an especially small footprint, look into ESP32-C3 SuperMini. These are just as worry-free and very cheap (less that €2).
- Super Many GPIOs - ESP32-S2: a true bargain with a massive 27 GPIOs is the single-core ESP32-S2 Mini, also often available for under €2. This board is pin-compatible with the popular Wemos D1 Mini (ESP8266) and can use the same shields, i.e. for supplying rechargeable battery power. The S2 Mini is not perfectly suited for beginners though: it has a strange USB port implementation that can require workarounds before you can upload new firmware.
The ESP32 family is constantly growing. Latest models such as ESP32-C6 or ESP32-H2 target new wireless technologies such as Matter or Thread, but are not yet fully supported by many development environments and code examples. You typically have to program them using the Espressif framework, and cannot use Arduino code. That’s why you should avoid these unless you really need their unique selling points.
Do not purchase ESP8266 anymore. They are outdated, considered unsafe (no https support), and cost just about as much as ESP32.
ATTiny
If you need a microcontroller to just control hardware and sensors in very space-constrained environments and with extremely low energy consumption, then ATtiny is a good way to go.
Very Small
These microcontrollers often do not come on development boards. To program them, you need a separate programmer board where the microcontroller is temporarily plugged in.
ATTiny microcontrollers are exceptionally expensive when comparing their capabilities to other microcontroller families, and their computational power, number of GPIOs, and memory is very limited.
Very Battery-Efficient
They shine when it comes to power consumption: running at a clock speed of 1MHz, the ATTiny85 consumes less than 2mA (compared to 130mA for an ESP32 with WiFi). If you use the microcontroller in watchdog mode and wake it up only occasionally, i.e. to take some sensor readings, it consumes just 5uA in standby (compared to 200-900uA in ESP32 deep sleep for typical development boards).
Raspberry Pi
Raspberry Pis are also popular DIY microcontrollers, although these really are CPUs, and they are used for running real operating systems, much similar to classic PCs.
Raspberry Pis are not to be confused with Raspberry RP2040 (which is the first microcontroller produced by Raspberry). The RP2040 is comparable to ESP32 and targets small devices.
Raspberry Pi 5 is the latest Raspberry Pi and compared to its predecessors, it is much more powerful. It can be used as an always on server, running Linux or Home Assistant.
Recommendations
Use Raspberry Pi 5 to complement your microcontrollers, and operate an efficient always-on server.
Some argue that a Mini PC would be much more powerful than a Raspberry Pi 5 at almost the same cost, but that is not true: the unique selling point for a Raspberry Pi 5 is its ultra low power consumption.
When you run a Mini PC plus virtualization software, computing power is much higher, but so is your electricity bill. The difference can quickly be a few hundred Euros per year.
- Simple Server: if all you need is operating a simple server or Home Assistant, then use Raspberry Pi 5 with SSD hard drive. It’s the most efficient solution with the lowest TOC (total cost of ownership). For this use case, running a Mini PC would be overkill, and the Mini PC would idle most of the time while burning electricity.
- Heavy Duty Server: if your requirements are much higher, and you’d like to run a multitude of services and/or servers, then pick a classic computer or mini-PC, and use virtualization software on it.
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(content created May 22, 2024)