Looking for a cheap and easy-to-assemble oscilloscope? Here is a guide on how to make one using a Raspberry Pi Pico.
f you’re into making electronics projects, it is only a matter of time before you realize how useful an oscilloscope can be. However, oscilloscopes can be prohibitively expensive for someone just getting started with PWM and digital logic analysis. The good news is that you can build your own low-cost 200kHz oscilloscope with a Raspberry Pi Pico microcontroller board and free Scoppy software.
What Can You Do With a Pi Pico Oscilloscope?
The deivce you’ll make is a low-frequency oscilloscope that can measure voltages of up to 3.3V. Although this isn’t much, as long as your project doesn’t go beyond the limit of the Pi Pico’s capabilities. You can still use this oscilloscope for projects involving pulse-width modulation (PWM), sensor characterization, digital logic analysis, and audio electronics.
Although primarily an oscilloscope, this DIY device also comes with other functionalities such as a logic analyzer! This means you can also use this as a learning tool to better understand the various communication protocols and experiment with PWM and low-power electronics.
Step 1: Install Scoppy Android App
First, you will want to download and install the Scoppy app for your Android phone or tablet device. This is used to display the oscilloscope GUI.
Step 2: Install Scoppy Pico Firmware
Download the correct firmware for the type of Raspberry Pi Pico you’re planning to use: the regular Pico or the Pico W with wireless connectivity.
Once you’ve downloaded the relevant firmware, press and hold the BOOTSEL button on the Pi Pico. Then connect it to your computer with the USB cable and release the button. This should cause the Pico to be detected as a mass-storage USB device.
Now copy the .uf2 file you’ve just downloaded and place it on the Pico’s mass storage device. While transferring, the onboard LED on the Pi Pico should be blinking. This indicates that the file is being transferred from the computer to your Pico
Step 3: Add a Current-Limiting Resistor
This step isn’t necessary for the Pico oscilloscope to work, but it will ensure that the board is protected in case you probe into voltages higher than the 3.3V limit. We’ve decided to add this as part of the base build.
For a temporary rig, fasten the Pico’s GND, 3.3V, and GP26 pins to the breadboard using straight male pin headers.
You can use the two male-to-male jumper wires as the probes, where the GND connects to ground, and the GP26 pin connects to the signal output of the electronic circuit you want to test.
Step 4: Connect Raspberry Pi Pico to Android Device
An Android phone or tablet is needed to provide a GUI (graphical user interface) for the Raspberry Pi Pico oscilloscope. To connect it, you’ll need to use an Android device that runs on Android 6.0 or higher and has USB OTG support.
Once you connect your smartphone to the configured Pico board via USB, open the Scoppy app on the phone and select Allow on the prompt that asks for permission to use the USB device with the Scoppy app.
Congratulations! You have successfully set up the Pico-based oscilloscope.