The “brains” of your robot will be some kind of processor or microcontroller. This is simply a chip (and associated electronics) that we will program to provide instructions to your robot.
There are many choices here, but the most popular at the time of writing are:
- Arduino – Atmel AVR based boards with associated development ecosystem of software and add-on boards.
- Linux single board computers, most popular with Makers is the Raspberry Pi.
- ESP8266/NodeMCU – Wifi capable boards based around the ESP8266.
Really our choice comes down to two: a microcontroller or a single-board computer.
Arduino and Microcontrollers
Under just the Arduino banner there is a LOT of choice. There are several Arduino branded boards, many boards based on the same reference designs, and then there are cheap clones of the originals. We will look at some of the choices when we get deeper into the wireless remote control aspects.
The way I use the ESP8266 boards it’s either with or instead of an Arduino. The boards built around the ESP8266/ESP32 can be programmed using the Arduino environment, using the same code. You can also use it as an add-on board to give an Arduino connectivity. So with those things in mind, we can really talk about it as being in the Arduino family the same way Arduino boards can be based on AVR chips (Atmel, now Microchip) or Arm chips, or even 8 bit versus the brainier 32 bit chips. It’s a family of many choices, which is cool.
For those in the know, yes there are other microcontrollers like Pic and such, but I am not going to cover those here because the use-cases for a Pic are well covered by Arduino and compatibles.
Microcontrollers are cheap (which is good because eventually you WILL kill yours), easy to work with (once you learn the basics), and do what they do reliably. They boot up instantly, and also suck down very little power when they are running (like run off regular 9v battery for a long time) and can be made to go to sleep when not doing anything which uses even less power.
These advantages are because of the main downside; they are not very powerful. The cheaper ones will have RAM measured in bytes rather than gigabytes, little to no storage, and the most popular Arduino chips are still 8-bits which puts us in Atari 2600 and Commodore 64 territory. Generally speaking, though, that does not matter because you are going to use a microcontroller to do something simple like move a motor, blink lights, perhaps play a happy tune.
Since the first version of this course, two newer boards have come on the scene that sit partway between the 8-bit Arduinos and the Raspberry Pi. The ESP32 adds WiFi and Bluetooth to a much faster chip, and the Raspberry Pi Pico, built on Raspberry Pi’s own RP2040 and RP2350 chips, is a cheap and capable microcontroller you can program in C, MicroPython or the Arduino IDE. Both still start instantly like a microcontroller, but with far more speed and memory than the classic Arduino, which makes them a great fit for robots that need wireless control or a bit more brainpower.
Linux Boards
I mention the Linux boards plural above. Yes, the Raspberry Pi currently wears the crown, but there are always new competitors launching. BeagleBone is the most famous, but you might well have heard of others over the years such as the CHIP, the “$9 computer”, and the Onion, both of which had successful Kickstarters.
The main advantage of these puppies is they generally have the ability to do proper computer stuff – powerful, multi-tasking grown up stuff. Everything from multimedia, computer games, to word processing, graphics/illustration, slicing 3d printing objects, motion video, and so on.
Of course for the purposes of robots this is awesome. We can stream video so we can see what the robot sees, we can have large databases, full web capability, heck even voice control, computer vision and machine learning. We can also use pretty much any programming environment or language we like, from industrial strength through to made-for-learning visual languages.
BUT the biggest strength, that multi tasking super power, does have one problem. Things like controlling servos and such requires real time not “wait a second I am doing something right now”. That can cause jitter or even to lose signals.
These boards take a while to boot, and can also be power hogs, so you need beefier batteries or mains power. If power drops while running, they can get upset and stop working until you recreate the operating system files. Talking of power, the GPIO pins where you would wire up sensors etc are not very resilient, they usually expect 3v, and probably won’t have much in the way of analog.
Either or AND?
Both broad groupings have strengths and weaknesses, but these strengths and weaknesses are remarkably complimentary, so you can do some amazing things by combining a micro controller and a Linux single board computer!
In our later examples we will look at using an Arduino compatible board to speak to the motors, sensors, and electronics, and we will use connected Raspberry Pi to handle things like the webcam, web interface, and generally being in charge.
