In a recent article in Elektor magazine, [Clemens Valens] describes the construction and software for an ESP32 walkie-talkie system that uses ESP-NOW for the wireless connection between units, along with a low-cost condenser microphone with a transistor-based preamplifier and an LM386 op-amp for the speaker circuit. In the ESP32 module the built-in DAC and ADC are used for audio in and output, which provide just about enough resolution for voice communication.
So why use ESP-NOW rather than WiFi or Bluetooth? Mostly because of range, power usage and convenience with no SSIDs and passwords to bother with.
ESP-NOW is Espressif’s own network protocol that uses the same underlying hardware as 2.4 GHz WiFi and Bluetooth, but focuses on more basic direct and mesh-style communication. It can be considered to be somewhat like low-level UDP with MAC address instead of IP address, which makes it useful for fire-and-forget traffic such as from IoT devices.
In the past, we’ve seen ESP-NOW control everything from fake security cameras to CNC machines. In fact, we’ve even seen it used in another walkie-talkie a couple years back.
DIY Walkie-Talkie With ESP32 And ESP-NOW
Source: Manila Flash Report
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