VSCode Cortex Debugging

Use F5 or the menu Run > Start Debugging to start a debug session:

This starts debug session. In case of troubles, check the Debug Console:

Debug Console Output

Launching GDB: /opt/toolchains/gcc-arm-none-eabi-10.3-2021.10/bin//arm-none-eabi-gdb -q --interpreter=mi2 /home/jshankar/codeprojects/tm4c123gxl/blinky/build/blinky.elf
Set "showDevDebugOutput": true in your "launch.json" to see verbose GDB transactions here. Helpful to debug issues or report problems
Reading symbols from /home/jshankar/codeprojects/tm4c123gxl/blinky/build/blinky.elf...
Launching gdb-server: /usr/bin/openocd -c "gdb_port 50000" -c "tcl_port 50001" -c "telnet_port 50002" -s /home/jshankar/codeprojects/tm4c123gxl/blinky -f /home/jshankar/.vscode/extensions/marus25.cortex-debug-1.2.0/support/openocd-helpers.tcl -f board/ek-tm4c123gxl.cfg
Please check TERMINAL tab (gdb-server) for output from /usr/bin/openocd
0x00000000 in g_pfnVectors ()
Program stopped, probably due to a reset and/or halt issued by debugger
2
adapter speed: RCLK - adaptive
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000354 msp: 0x2000021c
adapter speed: RCLK - adaptive
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000354 msp: 0x2000021c
adapter speed: RCLK - adaptive
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000354 msp: 0x2000021c
Note: automatically using hardware breakpoints for read-only addresses.

Temporary breakpoint 1, main () at /home/jshankar/codeprojects/tm4c123gxl/blinky/src/main.c:16
16	    SYSCTL_RCGC2_R |= 0x00000020;

By default there are several debug views available. With the .svd file, we have access to the peripheral register too:

Debug Commands

There are the usual debug commands (continue, stepping, restart) plus a run and debug toolbar

Continue / Pause F5
Step Over F10
Step Into F11
Step Out Shift+F11
Restart Ctrl+Shift+F5
Stop Shift+F5

Assembly Stepping

Press CTRL+SHIFT+P to invoke command palette. Then Select Cortex-Debug:View Disassembly(Functon), type the function name you want to disassemble.

0x000002ac: 80 b5           	push	{r7, lr}

0x000002ae: 00 af           	add	r7, sp, #0

0x000002b0: 0e 4b           	ldr	r3, [pc, #56]	; (0x2ec <main+64>)

0x000002b2: 1b 68           	ldr	r3, [r3, #0]

0x000002b4: 0d 4a           	ldr	r2, [pc, #52]	; (0x2ec <main+64>)

0x000002b6: 43 f0 20 03     	orr.w	r3, r3, #32

0x000002ba: 13 60           	str	r3, [r2, #0]

0x000002bc: 0c 4b           	ldr	r3, [pc, #48]	; (0x2f0 <main+68>)

0x000002be: 0e 22           	movs	r2, #14

0x000002c0: 1a 60           	str	r2, [r3, #0]

0x000002c2: 0c 4b           	ldr	r3, [pc, #48]	; (0x2f4 <main+72>)

0x000002c4: 0e 22           	movs	r2, #14

0x000002c6: 1a 60           	str	r2, [r3, #0]

0x000002c8: 0b 4b           	ldr	r3, [pc, #44]	; (0x2f8 <main+76>)

0x000002ca: 0e 22           	movs	r2, #14

0x000002cc: 1a 60           	str	r2, [r3, #0]

0x000002ce: 4f f4 fa 70     	mov.w	r0, #500	; 0x1f4

0x000002d2: 00 f0 13 f8     	bl	0x2fc <delayMs>

0x000002d6: 08 4b           	ldr	r3, [pc, #32]	; (0x2f8 <main+76>)

0x000002d8: 1b 68           	ldr	r3, [r3, #0]

0x000002da: 07 4a           	ldr	r2, [pc, #28]	; (0x2f8 <main+76>)

0x000002dc: 03 f0 f1 03     	and.w	r3, r3, #241	; 0xf1

0x000002e0: 13 60           	str	r3, [r2, #0]

0x000002e2: 4f f4 fa 70     	mov.w	r0, #500	; 0x1f4

0x000002e6: 00 f0 09 f8     	bl	0x2fc <delayMs>

0x000002ea: ed e7           	b.n	0x2c8 <main+28>

```
0x000002ec: 08 e1           	b.n	0x500
```

0x000002ee: 0f 40           	ands	r7, r1

0x000002f0: 00 54           	strb	r0, [r0, r0]

0x000002f2: 02 40           	ands	r2, r0

0x000002f4: 1c 55           	strb	r4, [r3, r4]

0x000002f6: 02 40           	ands	r2, r0

0x000002f8: fc 53           	strh	r4, [r7, r7]

0x000002fa: 02 40           	ands	r2, r0

It is possible to set breakpoints in the assembly code, but one cannot see high level (C/C++) side-by-side with the assembly code. And the disassembly view does not show any more information or symbolic as the Eclipse CDT disassembly view does.

Memory

To view memory, use the Command Palette (CTRL+SHIFT+P) with Cortex-Debug:View Memory.

Then specify the expression for the memory location and a length.

VSCode Cortex Debugging