🔨 Compilation

• Before trying to debug, the code must be compiled into a file executable by the STM32: a file with the .elf extension
• To compile, you can either:
  • type Ctrl + Shift + P, then type run task, and finally select the Make task
  • click on the Maketask in the Task Runner tab under the Explorer
  • ⚠ There are 2 make and clean tasks on the picture because the opened folder (EPuck2_Workplace/Lib) has tasks for testing the e-puck2_main-processor and ST libraries

🚀 Launch debugging

• First you must specify the port to which the gdb-server is connected, click here for more info
• First make sure to be in the Run and Debug tab (1)
• Open the choice box (2) and select the corresponding launch configuration at (3) among
  • BMP launch to main, launch and stop the program at the start of the main function
  • BMP launch to reset, launch and stop the program at the very beginning of the program (where the PC=0)
  • BMP attach, connect (attach) to an epuck2 already running the program
  • ⚠ There are 6 launch configurations on the picture because the opened folder (EPuck2_Workplace/Lib) has configurations for testing the e-puck2_main-processor and ST libraries
  • And finally launch the selected configuration by pressing the green ▷ (4)

🌌 Usage of the debugger

• It is possible to debug in many different ways once the debugger is connected to the EPuck2
  • Breakpoint: to stop the program once the PC reaches a specific line, click on the left of the line, manage all breakpoints in
  • Restart or Reset: the EPuck2: Has the same effect as if the hardware reset button is pressed
  • Continue: un-freeze the execution of the program
  • Step over: the PC runs until it hits the next line of source file
  • Step in: the PC jumps into the sub-routine of the current line
  • Step out: the PC jumps out of the sub-routine and goes back to the parent sub-routine
  • Stop: disconnects the debugger from the EPuck2; the EPuck2 will continue to run the program on its own
• There are many ways to monitor information using the debugger
  1. Variables: displays registers, local, global and static variables
  2. Watch: displays variable content, support C syntax (&i displays the address of the i variable, i/1000 displays the value i / 1000)
  3. Call stack: keeps track of the currently active sub-routines
  4. Breakpoints:
  5. Cortex Peripherals: displays the cortex peripherals registers' values
  6. Cortex registers: display the cortex's registers
• It is possible to see the assembly code of your program, you can either:
  1. View the assembly code of a single function
     • Open the Command Palette (Ctrl + Shift + p)
     • select Cortex-Debug: View Disassembly (Function)
     • specify the function name to analyze (ex: main)
     • the function assembly code will then be diplayed
  2. View the assembly code of the currently executed intructions
     • Open the Command Palette (Ctrl + Shift + p)
     • select Open Disassembly View
     • the currently executed instructions will be displayed in C and in assembly
• It is possible to check the memory content
  • Open the Command Palette (Ctrl + Shift + p)
  • select Cortex-Debug: View Memory
  • specify the start and the lenght of the memory segment to be analyzed

🛶 Example

• In this example, we put a breakpoint on the line 47
• Once the PC reaches this breakpoint, we click on Step into
• the PC then jumps in the content of the sub-routine gpio_toggle()
• In the Call stack tab, you can see currently active sub-routines
  • the active sub-routine is the one on the top of the list
• to go out of this sub-routine and be back in the main function, we can either:
  • Click on Step out
  • Click on Step over until the PC reaches the end of the sub-routine

💡 Further readings

• Cortex-Debug extension's wiki