Various Projects Find Hidden SDR Capabilities in ESP32 Microcontrollers
Researchers have discovered an undocumented feature in ESP32 microcontrollers that allows them to capture raw IQ baseband radio samples. This capability effectively turns these low-cost chips into software-defined radios (SDRs) for various frequency bands.
Why it matters
This discovery democratizes access to radio frequency analysis and signal processing, enabling hobbyists and researchers to perform advanced tasks like direction finding using inexpensive hardware.
Back in 2025, we posted about ESPARGOS, a phased array of many patch antennas, each connected to an ESP32 WiFi microcontroller. ESPARGOS could be used to determine the direction of arrival for WiFi signals and create a live augmented reality heatmap.
Recently, the ESPARGOS team has made an exciting discovery . They found that several ESP32 chips have an undocumented feature that lets the firmware bypass the fixed WiFi and Bluetooth functionality and instead capture raw IQ baseband samples. As a result, several ESP32 models can now be used as an internal SDR covering 2.2–2.7 GHz, plus 4.8–6.0 GHz on the ESP32-C5, with up to 80 MS/s sample rate and roughly 13–54 MHz of analog bandwidth, depending on the chip.
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