Why is my serial output garbled?
Garbled serial output nearly always comes down to one of three things:
1. Wrong baud rate
Every character is junk, including English letters and digits. Both sides must use the same rate; common ones are 9600, 115200 and 921600 (the ESP8266 boot log uses 74880).
In QCCOM, let the device print something, then click ⚡ Auto next to the baud rate. It tries 18 common rates, scores the text for readability and connects with the best one.
2. Wrong text encoding
English is fine but non-ASCII text (for example Chinese) turns into question marks or symbols. The firmware prints GBK while the tool shows UTF-8, or the other way round. Switch the Encoding between UTF-8 and GBK in QCCOM; the existing log is redrawn immediately.
3. Frame format or wiring
Most devices use 8N1. Check that TX goes to RX, RX to TX, GND is shared and the voltage levels match (do not connect 3.3 V / 5 V TTL to RS-232).