Talk Is Cheap: A $15 DIY Walkie-Talkie Project
Turn your Raspberry Pi Pico W into a DIY walkie-talkie using built-in Wi-Fi and a few basic components for low-latency voice chats.
Everybody knows that Raspberry Pi Pico development boards are useful for everything from blinking some LEDs to powering a desktop robot or a retro handheld gaming console. But the possibilities extend far beyond these common applications. YouTuber 101 Things recently demonstrated an unusual, but very interesting, use case for these little boards—making walkie-talkies.
By following the steps taken by 101 Things, a walkie-talkie or intercom system can be hacked together in a matter of minutes using only inexpensive and accessible hardware. The project was designed around a Raspberry Pi Pico W, which is equipped with built-in Wi-Fi. That wireless capability allows two devices to communicate directly without requiring a traditional radio module. Instead of transmitting audio over RF frequencies like classic walkie-talkies, these devices convert voice into digital data and send it across a Wi-Fi connection.
To capture sound, the build uses a MAX4466 microphone module, a small and inexpensive board that outputs an analog signal compatible with the Pico’s built-in Analog-to-Digital Converter (ADC). The signal is sampled and processed by the microcontroller before being transmitted over the network.
On the playback side, the project relies on a MAX98357A digital audio amplifier. This compact I2S Class-D amplifier can deliver up to 3 watts of power into a small speaker, making it more than capable of driving the build’s tiny 30 mm speaker. Because the amplifier accepts digital audio via I2S, it pairs neatly with the Pico’s digital output capabilities.
Instead of adding extra buttons and LEDs for the user interface, the project takes advantage of the Pico’s built-in hardware. The onboard BOOTSEL button doubles as a push-to-talk control, while the onboard LED provides status feedback. Different blinking patterns indicate connection stages such as searching for a partner device, establishing a Wi-Fi link, and being ready to transmit.
Communication between the two units uses a “fake peer-to-peer” networking method. When powered on, the devices automatically negotiate their roles. One becomes a Wi-Fi access point while the other connects as a station. Once the pairing succeeds, those roles are saved in flash memory so the devices can reconnect almost instantly the next time they start.
Audio transmission is handled through UDP packets to minimize latency. The system compresses audio samples from 12 bits down to 8 bits using A-law compression before sending them across the network. On the receiving side, the audio is expanded back to 12 bits and passed to the amplifier for playback.
A 1 kΩ resistor placed in the microphone’s power line forms a low-pass filter with the module’s onboard capacitors, helping eliminate noise from the Pico’s Wi-Fi radio. Meanwhile, a software noise gate suppresses background hiss and prevents feedback when neither device is actively transmitting. The hardware is housed in a 3D-printed enclosure and is powered by AA batteries.
If you’d like to build your own Pico-powered walkie-talkie, the build instructions and source code have been made publicly available.
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