The Raspberry Pi Pico misses two important things. The first is a reset button, easy to fix with a DIY hack or you can buy something more permanent. The second is wireless communication, namely Wi-Fi and Bluetooth. Pimoroni’s Pico Wireless is a $17 (£12) add-on package that works as a HAT or shield and provides Wi-Fi and a Micro SD card reader through the SPI interface.
Adding Wi-iFi to a Pico isn’t that hard, Adafruit has already proven this via ESP32 powered AirLift FeatherWing that works with the Pico and Adafruit’s own Spring RP2040 plate. Cytron’s Maker Pi Pico also supports the ESP8266. But adding Wi-Fi that’s compact and easy to use is still the holy grail for Pico users, and Pimoroni’s Pico Wireless could spell the end of our quest.
Design and use of the Pimoroni Pico Wireless
The Pico Wireless is a package designed to attach to all GPIO pins of a Raspberry Pi Pico (and Pimoroni’s Pico Lipo). It doesn’t use all GPIO pins, but it does prevent access. Since it is designed as a “package”, it fits perfectly into the footprint of the Raspberry Pi Pico and when plugged in we have a fairly compact project platform.
The built-in ESP32-WROOM-32E is itself a powerful microcontroller, but for the Pico Wireless it has been relegated to co-processor task in much the same way as Adafruit’s AirLift FeatherWing. The ESP32 is Wi-Fi and Bluetooth capable, but only Wi-Fi is available in this configuration, but capable hackers are sure to unlock additional capabilities.
If you need to use some GPIO pins, you need a breakout like the Pico Omnibus but you need to make sure you don’t have conflicting pins on your connected devices. The power for the Pico Wireless is provided by the GPIO of the Raspberry Pi Pico, providing an easy and practical way to power and program the boards.
The built-in microSD card slot (see best microSD cards) is a push-push mechanism ready to blast your micro SD card across the room. A single push button (A) is a convenient means of basic input and can be connected to GPIO 16. The only output is an RGB LED, again a useful addition for basic warning/error handling. The ESP32 and micro SD card reader can be disabled by cutting tracks on the bottom of the board; We don’t know why you would want this, but the process can be reversed by soldering a bridge between the tracks.
Hardware is nothing without software and Pico Wireless supports C++ and Pimoroni has its own MicroPython firmware with a “picowireless” module developed for use with the board. We tested this option against the sample scripts and while they worked well, they were very comprehensive and relied on the user knowing how networking works.
Until an abstracted library is written or we learn networking, the best way to use the Pico Wireless is Adafruit’s CircuitPython software. We used the same script that our Raspberry Pi Pico WiFi Project and only had to change a few lines to tell our Pico where the ESP32 was plugged in and copy a few libraries to the Pico. We were online in no time, receiving weather data from an online API. We modified the code with an additional library that enabled the built-in micro SD card reader. By inserting a blank FAT32 formatted card and writing a few lines of CircuitPython, we quickly created a new file with a log of the JSON data returned by the weather API. Data can also be read from SD with CircuitPython and used in your projects. The RGB LED is connected to the ESP32 via three pins (Red = 25, Green = 26, Blue = 27) and to use it we need to use esp.set_analog_write(). For example, here are the lines to set the LED to red.
esp.set_analog_write(25, 0)
esp.set_analog_write(26, 1)
esp.set_analog_write(27, 1)
We can use values between 0 and 1 to control the color of the RGB LED.
Finally, we tested the push button, connected to GPIO 12. We pulled GPIO 12 high and when the button is pressed, the pin connects to GND, effectively pulling the pin low and triggering an event in our code.
Use cases for the Pimoroni Pico Wireless
Wi-Fi on the Raspberry Pi Pico opens up a whole new world of Internet of Things (IoT) applications. Pico Wireless allows our humble Raspberry Pi Pico to communicate with devices using typical network protocols and others like MQTT. The CircuitPython library supports basic HTTP, creating access points and sockets. In our demo, we check the HTTP response from the API and print the value to the REPL, useful for troubleshooting connection issues.
Pico Wireless is ideal for adding to a data monitoring project, collecting data from sensors, storing the data on the micro SD card and sending the data to a remote machine. If you have the skills, robotics over the internet is possible with something like Anvil or Flask on another machine as a means of communication with the Pico.
Bottom Line
As a package, Pico Wireless is super easy to attach to your Pico, but you lose the ability to connect other components. This problem can be solved by using a breakout board, such as the Pico Omnibus, or by smart soldering. Still, Pico Wireless is a great tool. Once the MicroPython module goes through a few months of feedback and improvements, it will be much easier to use. Until then, it’s best to use CircuitPython.