ESP32 Chips Hide a Secret SDR Mode That Turns Them Into 80 MS/s Spectrum Analyzers
Various Projects Find Hidden SDR Capabilities in ESP32 Microcontrollers
The ESPARGOS team discovered an undocumented feature in several ESP32 chips that bypasses WiFi and Bluetooth to capture raw IQ baseband samples, turning the microcontrollers into internal SDRs covering 2.2–2.7 GHz (plus 4.8–6.0 GHz on the ESP32-C5) with up to 80 MS/s and 13–54 MHz of analog bandwidth. Two other projects independently found similar capabilities, though continuous streaming requires an FPGA or the new ESP32-S31.
The team also says phase-coherent transmissions would be possible, but they aren't implementing them right now because they could be misused.