If you have code that benefits significantly from compiler optimizations, you might want to try to compile in 'release with debug info' instead: cmake -DCMAKE_BUILD_TYPE=RelWithDebInfo As @darkp03 mentioned, make sure you are pressing QtCreator's 'debug button' (or shortcut key F5) and not the 'run' button.

@Tusharh Hi and welcome to devnet A featrure as you request may be latest with larger projects too much for the debugger to handle. The closest to get such a behaviour is to use F11 and Shift+F11. F11 will enter every possible method and Shift+F11 will help you to run the remainder of the method. IMO sufficient enough to get a really detailed anaylsis of source code.

To add to my fellow and maybe a silly question but since you build Qt yourself did you do a debug_and_release build ?

I added a delay function before reading the serial port, console->SenDelay(70); QByteArray data = serial->readAll(); now everything is working.