Garbage Data on Serial monitor


I have readymade working electronic product. I am applying reverse engineering on it. The WiFi module is connected to microcontroller via UART( RX & TX). The android app sends command to wifi and microcontroller works as per the command. I have attached a USB to TTL cable on RX and TX also command ground as well of WiFi module. The cable is connected to serial monitor on PC. When the app send data to WiFi, the serial monitor shows garbage value, which is not readable. I have checked every baud rate possible. Instead of USB to TTL cable, I also used HC05 bluetooth module. But it shows garbage value. How can I get the readable values on my serial monitor. Do i need to disconnect micro controller from WiFi??

Please help

Show us some pictures. You should connect your usb TTL adapter's rx to one of the rx or TX. Don't connect adapter TX to anything. Get a second adapter. Connect its rx to the other pin.

make sure that the rate set in your serial.begin and in the monitor are the same.