ESP-SDR Turns a Supported ESP32 into a 2.4/5 GHz Radio Receiver
Tags: ESP32, ESP32-C6, ESP32-S3, SDR, firmware, ESP-SDR, Wi-Fi, CrowPanel
CNX Software reports that ESP-SDR, open-source firmware from the ESPARGOS project, turns supported ESP32 chips into a low-cost software-defined radio receiver. No extra SDR dongle is required. The write-up is ESP-SDR firmware turns ESP32 into a 2.4/5 GHz Software-Defined Radio (SDR).
The firmware bypasses the fixed-function Wi-Fi and Bluetooth modems and taps a debug I/Q sampling path in the radio’s ADC chain. Samples, or a compact on-chip FFT spectrum, go to a computer over USB or UART. ESP-WebSDR, a browser tool, shows a live spectrum and waterfall. Supported chips in the article are the original ESP32, ESP32-C3, ESP32-C5, ESP32-C6, ESP32-C61, ESP32-S2, ESP32-S3, and the preview ESP32-S31. Tuning is nominally the 2.4 GHz ISM band, about 2.2–2.7 GHz on some chips. The ESP32-C5 also covers 5 GHz, about 4.8–6.0 GHz. The C61 can tune to 2.7 GHz and capture LTE Band 7 and 5G NR Band n7. Sample rate is up to 80 MSa/s, with roughly 13–54 MHz of bandwidth depending on the chip.
USB and UART cannot carry the full raw stream, which can reach 2.56 Gbps, so the browser tool takes short I/Q snapshots and can miss signals between windows. Continuous streaming is still in development: SoapyESPSDR on the ESP32-S31 is aimed at Gigabit Ethernet at 8–16 MSa/s for GNU Radio and Gqrx. Flash a supported board from Chrome or Edge with the ESP-WebSDR flasher. Source is on GitHub under GPL-3.0. Check local laws before receiving RF signals.
Shop a compatible board at ameriDroid
The article does not name a specific board. Any development board with a supported chip and a USB connection can be flashed. These boards are in stock. None is an ESP32-C5, so they cover 2.4 GHz only. Dual-band 5 GHz reception needs a C5 board, which is not in the current catalog. The displays below use a supported chip, but ESP-SDR does not ship a CrowPanel board definition, so treat a flash on those panels as experimental.
ESP32-C6 SuperMini
ESP32-C6, Wi-Fi 6, Bluetooth 5 LE, and 802.15.4 on a stamp-size board with USB-C. Native USB Serial/JTAG matches the chip table in the ESP-SDR repo. 2.4 GHz only. ESP32-C6 SuperMini — $6.95
XIAO ESP32-S3
Seeed Studio XIAO with an ESP32-S3, 8MB flash, 8MB PSRAM, 2.4 GHz Wi-Fi, and Bluetooth 5.0. USB-C, about 21 × 17.8 mm. XIAO ESP32-S3 — $10.95
Displays with a compatible ESP32
CrowPanel 2.01" ESP32-S3 watch display
ESP32-S3, 2.01-inch 240×296 IPS capacitive touch, microphone, and speaker. PCB only, no enclosure. CrowPanel 2.01" — $21.95
CrowPanel 1.28" ESP32-S3 rotary display
ESP32-S3, 1.28-inch 240×240 round IPS touchscreen, and a rotary knob with push. CrowPanel 1.28" — $29.95
CrowPanel 1.46" ESP32-S3 rotary display
ESP32-S3, 1.46-inch 360×360 round IPS touchscreen, rotary knob, and an RGB ring. CrowPanel 1.46" — $31.95
CrowPanel Advance 3.5" ESP32-S3
ESP32-S3, 3.5-inch 480×320 IPS touchscreen, case, microphone, speaker, and an SX1262 LoRa module. CrowPanel Advance 3.5" — $41.95
ESP32 AI camera board with 1.83" screen
Original ESP32, which is on the supported list, with a 1.83-inch screen and a camera. ESP32 AI camera board — $27.95