Question

s3c44b0x does not support flash breakpoint(unlike other processors such as lpc1758 which has on-chip flash), then how to debug bootloader when it still runs in the flash?

Answer 1

Logic analyzer, printf, ICE, and EPROM / Flash memory emulator would be the old-school ways.

The Samsung S3C44b0x (ARM7TDMI) claims to have an on-chip ICE breaker debug support, so getting a In-Circuit Emulator might be what you want to do.

Added:

If you have enough RAM, during the booting from Flash you could print log messages to an in-memory buffer in RAM, and then output this buffer, using printf to serial later once the UART is initialized.

2nd addition:

To isolate which portion of the bootstrap process, you could replace modules or steps with empty stubs, with the sole intent to isolate crashing. The approach is to narrow the possibilities of failure. Make an firmware image that initializes only the first basic step e.g. the system’s memory, if that works add your task or process housekeeper module / step, later including initializing the UART, etc.

If you have the output pins, add some LEDs to count the sections in binary, allowing your to see which section of code is currently running.

Check out the book Debugging Rules and print off your own copy of the free Rules of Debugging poster. It’s a short book, and while nothing revolutionary it solidifies the debugging process, and helps most people be more organized and methodical in their debugging.

References:

• The ten secrets of embedded debugging
• SO: What simple method can I use to debug an embedded processor without serial port or video?
• Softpanorama Debugging Links