Raspberry Pi Pico – The Tiny Microcontroller

When is a computer not a computer: when it’s a microcontroller. To be fair, a computer, by its true definition, is an electronic device for storing and processing data, which is what the Pico does. But for most users, a computer is defined as a device that sits on a desk, something you can work and play on. This is where the Pico differs.

The Pico is something entirely different from the Raspberry Pi Foundation’s usual releases. Whereas the Raspberry Pi, now on version 4, is a small computer, and even the Compute Module and the Pi 400 are still just computers, the Pico is actually a microcontroller.

A microcontroller is a processing unit that’s designed to work with programmable peripherals, and has input and output modules alongside a small amount of memory and storage capabilities. The processors are often scaled down, compared to the processor on a Raspberry Pi, or even inside your desktop computer, but powerful enough to complete basic tasks.

Examples of a microcontroller in action can be found inside a washing machine, or traffic lights. A washing machine has no need for a quad-core processor, 8GB of memory, and the ability to output to a 4K monitor. Instead, it has a set of microcontrollers, that are connected to various parts of the washing machine – such as the pump, or motor. When a signal is sent to an input on the washing machine’s microcontroller, it knows – through some clever programming stored in its limited memory – that it needs to send a signal output to the valves to allow in a certain amount of water, then activate the motor for the drum and so on.

A basic microcontroller circuit board inside a washing machine.

The same can be applied in the traffic light example. A powerful computer isn’t necessary, so a microcontroller will activate the red, amber and green lights in sequence, or switch to red to stop traffic when someone presses the Walk button.

While it would probably be interesting to have a powerful computer inside your washing machine, it’s overkill. A microcontroller takes up less space, uses less energy, and isn’t prone to the kind of crashes and in need of the frequent updates that a traditional computer requires. They simply sit there, act on input that comes their way, processes that data, and outputs whatever is required depending on the input actions.

Power use is the main reason why microcontrollers are in action everywhere we look. There’s often limited supply to devices, or situations. A microcontroller can work effectively with the limited amount of energy drawn from a small solar cell – even in the most overcast of northern climes. For example, on-board the International Space Station, there are thousands of microcontrollers in action: monitoring air quality, monitoring radiation levels, distributing power, and keeping track on the crew. If each of these units were a more powerful computing device, the power draw on the ISS would be immense; so microcontrollers are the way forward – at least until we work out how to build a warp core and near unlimited energy, that is.

Programmable Pico

The main difference between the microcontrollers inside your everyday appliances and the Pico, is that where the microcontrollers within your washing machine are pre-programmed with their instructions, the Pico isn’t and can be programmed by you.

This means that you can use the Pico’s USB port to connect to a computer, write some code to control something, upload the code to the Pico’s RP2040 microcontroller, and watch as it does what you’ve asked it do.

The 26 multi-function GPIO pins, located down the long sides of the Pico, can be used to solder electronics projects to. And with some clever coding, you’re able to control the input and output of devices depending on their state via the Pico microcontroller.

Each of the Pico’s GPIO pins have specific uses, as you can see from the pinout chart. This means that certain electronic components soldered to the pins, can be programmed using the Pico’s primary microcontroller language, MicroPython (or C++).

The Raspberry Pico GPIO mapping.

Remember, it’s not a Pi

It’s worth mentioning that the Raspberry Pico isn’t designed the same as, or to replace a Raspberry Pi. This is a different type of device altogether. Where you’ll use your Pi to browse the internet, play a game, do some coding and so on, the Pico can’t do that. It’s designed for use with physical components and projects, such as lighting LEDs or responding to a button push, controlling motors and the like.

If you want more versatility for your projects, then the Raspberry Pi is still the perfect device to use. If you’ve got something specific in mind, and you want to expand into electronics and microcontrollers, then the Pico will fit the bill. But, you’ll also need a computer, or Raspberry Pi, in order to program the Pico to begin with.

Find more guides like this in…

Russ Ware

Russ has been testing, reviewing and writing guides for tech since the heady days of Windows 95 and the Sega Saturn. A self-confessed (and proud) geek about all things tech, if it has LED's, a screen, beeps or has source code, Russ will want to master it (and very likely take it apart to see how it works...)

Related Articles

Back to top button