Understand the Breakpoint Issue Context
All developers face breakpoint issues during debugging. In Keil uVision, these may arise due to several reasons such as incorrect memory mapping, misconfiguration, or hardware limitations. Before diving into the resolution, it’s crucial to understand the exact nature of your breakpoint issue. Check if:
- Breakpoints are being hit inconsistently.
- The debugger skips or ignores the breakpoints.
- There are warnings or errors related to breakpoints in the debug output.
Check Compiler Optimizations
Optimizations can often rearrange code, causing breakpoints to behave unexpectedly.
- Access the Keil uVision project options and navigate to the "C/C++" tab.
- Ensure that the optimization level is set to "None" or a lower level of optimization for debugging purposes. This will help in more predictable behavior of code execution and breakpoints.
Review Memory and Code Placement
Improper memory mapping can result in breakpoints not functioning correctly:
- Ensure that your code sections are allocated to valid memory areas in your linker script or scatter file.
- Verify that there are no overlaps or conflicts in your memory map.
For example, a scatter file configuration might resemble:
LR_IROM1 0x08000000 0x00080000 { ; load region size_region
ER_IROM1 0x08000000 0x00080000 { ; load address = execution address
*.o (RESET, +First)
*(InRoot$$Sections)
.ANY (+RO)
}
}
Make sure the addresses align with your specific hardware setup.
Increase the Hardware Breakpoint Limit
Most ARM targets have a limited number of hardware breakpoints. If this limit is exceeded, breakpoints may not function correctly.
- Review your debugger's manual to understand the hardware breakpoint limits.
- If necessitated, re-arrange or simplify your breakpoints to avoid exceeding hardware limits.
Debugging and Validation Options
Verifying the correctness of your debug configuration can sometimes resolve the issue:
- Go to "Debug” tab under your project's properties.
- Enable "Load Application at Startup" and verify if "Run to main()" is checked.
- Consider running the "Debug" settings in verbose mode for additional insights.
Using Semihosting and Serial Wire Outputs
If breakpoints are bypassed, an alternative debugging approach using semihosting or SWO can be beneficial. Implement printf-like debugging to inspect variables, program flow, or other conditions:
#include <stdio.h>
int main() {
int value = 100;
printf("Debug Value: %d\n", value);
while(1);
}
- Note: The debugger configurations must support semihosting or SWO for this mode.
Inspect IDE and Plugin Compatibility
Sometimes, the plugins or extensions in Keil uVision can conflict or go out of date.
- Verify that all components of Keil (including packs and plugins) are up to date.
- Sometimes reverting to previous versions could resolve plugin-related issues.
Consider Flash and Debug Speed Settings
Configuration of Flash and Debug speeds can impact runtime behavior when hitting breakpoints:
- Go to the appropriate settings under the 'Flash Download' and 'Debug' tabs.
- Ensure that frequencies set there are appropriate for your hardware.
By systematically identifying and addressing these potential causes, firmware developers can considerably mitigate and resolve breakpoint issues in Keil uVision debugger.
