Researchers from the ESPARGOS project have discovered an undocumented feature in ESP32 microcontrollers that allows the firmware to capture raw IQ baseband samples. This hidden capability effectively transforms several ESP32 models into functional internal software-defined radios covering the 2.2 to 2.7 GHz and 4.8 to 6.0 GHz frequency bands. The breakthrough bypasses the chips' standard wireless limitations, opening up new possibilities for low-cost radio frequency applications.