The Raspberry Pi Pico introduced a new set of add-on layouts for the 40 DIP layout board. Smaller add-ons are called “Packs”, for example the Pimoroni Pico Unicorn Pack† If there is a need for a larger board, we have “Base” and the first on our workbench is the $30 Pimoroni Pico Explorer an “embedded circuit experimental arena” that uses a series of GPIO pins, a small LCD screen, dual motor provides exits and two breakouts compatible with Breakout Garden boards.
The purpose of the Pico Explorer Base is to be a place for experimentation with electronic components, a purpose shared with the Explorer HAT range of boards for the raspberry pie† We tested Pimoroni’s Pico Explorer Base and built projects to test the board’s various features.
Design and use of the Pimoroni Pico Explorer
Measuring 4.6 x 2.5 x 0.8 inches (117 x 63 x 20 mm), Pico Explorer comes pre-assembled. The size of Pimoroni’s Pico Explorer Base is comfortable, we have enough space to work comfortably, but it doesn’t dominate our desk.
In the top left corner of the board we see a space for our Raspberry Pi Pico, placed with the micro USB port facing out. Connecting the Pico to the board also powers the board and its components. Just below the Pico is a mini breadboard on which we can build circuits and experiments.
In the center of the Pico Explorer Base is a series of GPIO breakout pins, but you will notice that not all GPIO pins are broken out as some are used by the onboard motor controller (GPIO pins 8 to 11), the piezo buzzer, LCD display and buttons. At the bottom right of the board dominates a 1.54 inch screen of 240 x 240 pixels with four buttons on the corners. This screen uses the same library as Pimoroni’s Display Pack, another board we’ll discuss. In the top right corner of the board are two Breakout Garden compatible slots for use with Pimoroni’s range of breakout boards. Finally hidden between these two slots is a single piezo speaker.
We tested Pico Explorer with the latest version of Pimoroni’s MicroPython image, which is still an alpha version, meaning work is underway to improve and streamline the experience.
Our first project was to flash an LED on and off, so we connected an LED to GP0 through the Pico Explorer Base. When we imported the picoexplorer library, we expected that there would be an abstraction that would allow us to blink an LED using Pimoroni’s own library. There was no such abstraction in the library, but why did we expect it? We have extensive knowledge of Pimoroni’s Explorer HAT series of boards for the Raspberry Pi, and they have a Python library that abstracts every aspect. Instead, we had to use the Pin class from the MicroPython machine library. Not a problem, because those new to the Pico Explorer probably wouldn’t have this knowledge.
The next project was a bit more ambitious, a single 6V DC motor controlled via a 10K Ohm potentiometer connected to an ADC pin. As we turn the potentiometer, the resistance changes and the output is used to control the speed of the motor connected to one of the two motor channels. Both motor channels use a DRV8833 motor controller, which is a popular chip for basic robotics.
The picoexplorer library had all the classes and functions needed to read the potentiometer and control the motor. We went a little further and added a section of code that would display the engine speed on the onboard screen, with speeds below 0.7 color coded green for slow, and speeds above 0.7 changing the text color to red and alerting the user.
We went a little further and attached an MSA301 three-axis accelerometer to one of the Breakout Garden slots. At the moment, Pimoroni is still working on the compatibility with MicroPython for pimples, so our efforts have not paid off even after some time.
For those unfamiliar with it, Pimoroni’s Breakout Garden is a line of breakout I2C and SPI boards that plug into matching slots on Raspberry Pi HATs and now the Pico Explorer Base. There is a huge ecosystem of boards that encompass everything from time-of-flight and color sensors to displays, thermal cameras and LED matrices. No doubt Pimoroni will add software support for Breakout Garden boards to the Pico Explorer Base, but at the time of writing this doesn’t work for most add-ons.
Usage scenarios for the Pimoroni Pico Explorer
The Pimoroni Pico Explorer Base is a place to experiment. We have the GPIO pins, the display and the motor controller that allow us to build some pretty advanced projects. For those starting their journey with code and electronics, the level of abstraction will help them take their first steps and, with subsequent updates to the library, we’ll see more abstractions to facilitate their learning. The two motor pins mean basic robots can be made with Pico Explorer, we just need to find a robot chassis to house the board, which has rubber feet but no screw holes for mounting.
At £22 ($30), Pico Explorer is a much bigger investment than just a Raspberry Pi Pico. The size and functions complement each other and the board is extremely useful
The core functionality is there, but unfortunately it’s not currently compatible with Breakout Garden boards, although this will certainly change in the near future as Pimoroni refines the software. We also wish the board would have some sort of mounting holes so you can easily place it on a robot. Overall, though, it’s a useful and fun tool for anyone experimenting with a Pico.