Programming Embedded Systems in C and C++

32 Chapter 4: Downloading and Debugging

All the host computer needs to talk to the monitor program is a serial port and a

terminal program. Instructions for loading an Intel Hex Format file, like blink.hex,

into the Flash memory device are provided in the “Target188EB Monitor User’s

Manual,” which is included with the board.

The biggest disadvantage of this download technique is that there is no easy way

to debug software that is executing out of ROM. The processor fetches and exe-

cutes the instructions at a high rate of speed and provides no way for you to view

the internal state of the program. This might be fine once you know that your soft-

ware works and you’re ready to deploy the system, but it’s not very helpful dur-

ing software development. Of course, you can still examine the state of the LEDs

and other externally visible hardware but this will never provide as much informa-

tion and feedback as a debugger.

Remote Debuggers

If available, a remote debugger can be used to download, execute, and debug

embedded software over a serial port or network connection between the host

and target. The frontend of a remote debugger looks just like any other debugger

that you might have used. It usually has a text or GUI-based main window and

several smaller windows for the source code, register contents, and other relevant

information about the executing program. However, in the case of embedded