Olimex ESP8266-EVB Evaluation Board w/ Relay & UEXT

Establish a 3.3V TTL UART connection using the RX, TX, and GND pins on the UEXT connector, typically via a USB-to-serial adapter. Power the board in standard 'boot from FLASH' mode (no buttons pressed). Use a terminal program like PuTTY or Arduino Serial Monitor, ensuring it is configured to send both Carriage Return and Line Feed (\\r\\n) at the end of each command. Commands are case-sensitive, so enter 'AT' followed by CR+LF to receive an 'OK' response.

The large button is used to force the ESP8266EX into UART download mode for firmware flashing. Hold this button down while applying power or resetting the board to enter the bootloader. This mode is required when uploading new firmware via serial using tools like esptool.py or the Arduino IDE. For normal operation, ensure the button is not pressed during power-up so the chip boots from its internal flash memory.

Yes, the board can be powered via the +5V and GND pins on the UEXT connector, which is convenient when using an Olimex UEXT-USB adapter or other UEXT-capable power source. Alternatively, you can use the dedicated 5V DC power jack. Ensure your power supply can provide sufficient current for the ESP8266 chip and any connected peripherals, especially when the onboard relay is actively switching a load.

The UEXT connector provides a standardized interface for Olimex and compatible modules, offering I2C, SPI, UART, and power lines. Simply plug in a UEXT module. For direct wiring, use the 16-pin header row which breaks out all ESP8266 GPIOs. Refer to the board's pinout diagram to identify pins for I2C (GPIO4/GPIO5), SPI (GPIO12-15), or other functions, taking care to use 3.3V logic levels for all connected devices.