ESP32 NTRIP Duo

ESP32 NTRIP Duo forwards a GNSS receiver UART over Wi-Fi. It supports two simultaneous NTRIP source connections, an NTRIP client, TCP/UDP server and client modes, a web interface, status LEDs, and optional SD-card logging.

Supported targets: ESP32, ESP32-C3, ESP32-S3, and ESP32-C6. The tested toolchain is ESP-IDF 5.4.4.

Install a release

1. Download the archive for the exact chip from Releases.
2. Extract it and select <target>-ntrip-duo-merged.bin.
3. Flash the merged image at offset 0x0, for example with ESPHome Web.

Do not flash the application-only <target>-ntrip-duo.bin at 0x0. The individual binaries are included only for tools that use every address listed in the archive README.

After flashing, connect to the open Wi-Fi network ntrip-DUO_danusha and open http://192.168.4.1.

Build from source

Install ESP-IDF 5.4.4, then load its environment and build:

jj git clone https://github.com/danusha2345/esp32-ntrip-DUO_danusha.git
cd esp32-ntrip-DUO_danusha
source "$HOME/esp/esp-idf/export.sh" # adjust to your ESP-IDF location

TARGET=esp32 # esp32, esp32c3, esp32s3, or esp32c6
idf.py set-target "$TARGET"
if [ -f "sdkconfig.$TARGET" ]; then cp "sdkconfig.$TARGET" sdkconfig; fi
idf.py build
idf.py flash

Run ./build_all.sh to build release archives for all four targets.

Default pinout

UART is configured as 115200 baud, 8N1, with RTS/CTS disabled. Cross TX and RX between the ESP and GNSS receiver.

Target	UART	ESP TX → GNSS RX	ESP RX ← GNSS TX	RTS	CTS
ESP32-WROOM	UART2	GPIO17	GPIO16	GPIO32	GPIO33
ESP32-C3	UART0	GPIO21	GPIO20	GPIO5	GPIO6
ESP32-S3	UART0	GPIO43	GPIO44	GPIO16	GPIO17
ESP32-C6	UART0	GPIO16	GPIO17	GPIO22	GPIO23

RTS and CTS are assigned only when their hardware-flow-control options are enabled.

ESP32-WROOM board shown in the wiring diagram

Use the esp32 firmware and wire the UM980 evaluation/breakout board as follows:

ESP32-WROOM board	UM980eb/breakout
GPIO17 (TX2)	RX
GPIO16 (RX2)	TX
GND	GND
5V	VIN, only when the carrier accepts 5 V

The UM980eb evaluation board accepts a 3.2–5.0 V supply. A bare UM980 module accepts only 3.0–3.6 V; never connect its supply pin directly to 5 V. Check the marking and documentation of a different carrier before powering it.

Do not use GPIO1/GPIO3 for this connection: they are UART0 and share the board's USB-to-UART bridge. Do not connect indicator LEDs to UART TX or RX. GPIO6–GPIO11 are connected to the ESP32-WROOM flash and must not be used. On ESP32-WROVER modules GPIO16/GPIO17 are normally used by PSRAM, so remap the UART in the web interface before wiring that module.

Existing installations retain UART settings stored in NVS. After updating, select UART2/GPIO17/GPIO16 in the web interface or erase NVS/factory-reset to receive the new ESP32-WROOM defaults.

LEDs

The RGB status LED must be common-anode: connect its common pin to 3.3 V and each colour cathode through its own 220 Ω resistor to the GPIO.

Target	RGB red	RGB green	RGB blue	RSSI	Sleep	Assoc
ESP32	GPIO21	GPIO22	GPIO23	GPIO18	GPIO27	GPIO25
ESP32-C3	GPIO8	GPIO9	GPIO10	GPIO2	GPIO3	GPIO4
ESP32-S3	GPIO4	GPIO5	GPIO6	GPIO18	GPIO21	GPIO47
ESP32-C6	GPIO4	GPIO5	GPIO6	GPIO18	GPIO19	GPIO20

SD card logging

Target	MISO	MOSI	CLK	CS
ESP32-C3	GPIO7	GPIO15	GPIO14	GPIO13
ESP32, ESP32-S3, ESP32-C6	GPIO2	GPIO15	GPIO14	GPIO13

All SD pins can be changed under SD logger configuration in menuconfig. On ESP32, GPIO2 and GPIO15 are strapping pins; avoid external pull resistors that force an invalid boot mode.

Security defaults

The access point is open, admin authentication is disabled, and the web interface uses unencrypted HTTP by default. Configure Wi-Fi and enable admin authentication before using the device on an untrusted network. HTTP Basic authentication protects access but does not encrypt credentials or traffic.

License

Licensed under GPL-3.0. Based on ESP32 XBee by Nebojsa Cvetkovic.