Key features - Direct USB-to-TTL testing: connect a USB-to-TTL module for quick verification and testing. - Fixed serial configuration: 9600 baud, 8 data bits, no parity, 1 stop bit. - Speaker driven by serial data: whatever is sent over the serial port is spoken by the built-in speaker. Example: printf("Hello everyone"); will broadcast "Hello everyone". Supports numbers, letters, and Chinese speech. - Serial port compatibility: the 1.5V and 3.3V microcontroller serial outputs can be driven directly, without additional level shifting. - Power and wiring: power input is 5V on the red line; ground on the black line. Serial I/O lines are green (RX) and yellow (TX). - Line sequence: red = 5V, green = RX, yellow = TX, black = GND. Use scenarios - Microcontroller projects needing audible prompts or alerts. - Educational demonstrations of serial I/O and speech output. - Prototyping voice-enabled embedded devices and proof-of-concept testing.