GND, TXD, 3V3, 5V pins are exposed on bendpin header for easy TTL serial connections. This compact breakout provides a clear and reliable way to interface microcontrollers and development boards with a host computer or USBtoserial adapter. Three indicator LEDs offer ataglance status: TXD LED to show transmit activity a general LED indicator POWER LED to confirm supply is present Power supply options: 5V external power supply 3.3V external power supply External supply in the 3.3V to 5V range Protection and safety: Reverseconnection protection with a 500 mA resettable fuse to help prevent damage during setup or wiring errors Key benefits: Simple TTL serial interface with clearly labeled pins for quick wiring and testing Flexible power options to suit 3.3V and 5V systems, including lab bench supplies Visual indicators reduce guesswork during debugging and development Builtin protection lowers the risk of damage from incorrect connections or voltage mismatches Compatibility and practicality: Suitable for use with 3.3V and 5V TTL devices, including microcontrollers and development boards Ideal for serial programming, debugging, and data monitoring in development workflows Use scenarios: Scenario 1: Debugging a 3.3V microcontroller project (for example, ESP32/ESP8266 or similar) by powering from a 3.3V external supply and monitoring TXD activity with the TXD LED. Scenario 2: Prototyping with a 5V Arduino or other 5V logic devices, using a 5V external power source for both power and signal reference, while using the POWER LED to verify power status. Scenario 3: Lab bench testing with a shared external supply in the 3.3V5V range, allowing flexible power configuration and safe operation due to reverseprotection and the 500 mA resettable fuse. This product delivers a straightforward, dependable serial interface with clear status indicators, flexible power options, and builtin protection, making it a practical choice for developers and hobbyists working with TTL serial communications.