Data transmitted from the module to the external device.
The module typically features two sides of pins for interfacing: TTL Side (Connect to Microcontroller) Power input (3.0V - 5.5V). GND: Ground. TXD: Transmit data (connects to MCU RX). RXD: Receive data (connects to MCU TX). RS-232 Side (Connect to PC/Serial Device) VCC/GND: Shared with the TTL side. TXD: RS-232 Transmit. RXD: RS-232 Receive.
The small form factor allows it to be embedded directly into DIY project enclosures or mounted onto custom PCBs. Common Use Cases: