Debug Nuvoton Cortex-M with VSCode/CMake and OpenOCD

This project demos :

1. Use gcc-arm-none-eabi/CMake to build Nuvoton Cortex-M program,
2. Utilize VSCode/Cortex-debug/OpenOCD to perform debugging.

Note, this mechanism is only been tested on "THIS" simple test program, use it on your risk.

+------------------------+
+ VSCode w/              +                    +------------------+
+ Cortex-Debug Extension + <--- USB (SWD) --->+ Nuvoton-PFM-M487 +    
+                        +                    +------------------+
+-------------------------

Source Tree

./nu-cmake-example  
├── cmake  
|   └── arm-none-eabi-gcc.cmake  
├── CMakeLists.txt  
├── flash.cfg  
├── README.md  
├── res  
│   ├── M480.svd  <-- M480BSP/Library/CMSIS/SVD/ARM_Example.svd  
│   ├── nulink.cfg <-- OpenOCD-Nuvoton/tcl/interface/nulink.cfg  
│   ├── numicroM0.cfg <-- OpenOCD-Nuvoton/tcl/target/numicroM0.cfg  
│   └── numicroM4.cfg <-- OpenOCD-Nuvoton/tcl/target/numicroM4.cfg  
└── User  
    └── main.c  

Environment

```shell
export PROJ_ROOT=`pwd`     
export M480BSP="folder-of-cloned-Nuvoton-M480BSP"  
```

Build and Install OpenOCD

Linux

• Install packages:

  sudo apt install gcc make automake autoconf pkg-config libtool libusb-1.0-0-dev libftdi-dev texinfo
  sudo apt install cmake gcc-arm-none-eabi gdb-multiarch

• Build and Install Nuvoton-OpenOCD:

  git clone https://github.com/OpenNuvoton/OpenOCD-Nuvoton
  cd OpenOCD-Nuvoton
  ./bootstrap
  ./configure --disable-werror --disable-shared --enable-ftdi
  make
  make install

  sudo cp ./contrib/60-openocd-nuvoton.rules /etc/udev/rules.d/
  reboot

• Test OpenOCD setup:

  Connect host USB to NuMaker-PFM-M487 and run:

  cd $PROJ_ROOT
  openocd -f ./res/nulink.cfg -f ./res/numicroM4.cfg

  Open On-Chip Debugger 0.10.0-dev-00477-g57b40002 (2022-03-20-08:29)
  Licensed under GNU GPL v2
  For bug reports, read
      http://openocd.org/doc/doxygen/bugs.html
  Info : auto-selecting first available session transport "hla_swd". To override use 'transport select <transport>'.
  Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
  Info : clock speed 1000 kHz
  Info : NULINK is Nu-Link1
  Info : NULINK firmware_version(7313), product_id(0x40012009)
  Info : IDCODE: 0x2BA01477
  Info : NuMicro.cpu: hardware has 6 breakpoints, 4 watchpoints

Windows

TBD

Build Example Program

• Clone BSP source tree:

  git clone https://github.com/OpenNuvoton/M480BSP
  export M480BSP=pwd/M480BSP

• Build and Write to Flash

  cd $PROJ_ROOT
  mkdir -p build && cd build
  cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-none-eabi-gcc.cmake -DCMAKE_BUILD_TYPE=Debug ..
  make

  Scanning dependencies of target nu-cmake-example.elf
  [ 11%] Building C object CMakeFiles/nu-cmake-example.elf.dir/User/main.c.obj
  [ 22%] Linking C executable nu-cmake-example.elf
  text    data     bss     dec     hex filename
  30704    2536      92   33332    8234 nu-cmake-example.elf
  write to flash ...
  Open On-Chip Debugger 0.10.0-dev-00477-g57b40002 (2022-03-20-08:29)
  Licensed under GNU GPL v2
  For bug reports, read
          http://openocd.org/doc/doxygen/bugs.html
  Info : auto-selecting first available session transport "hla_swd". To override use 'transport select <transport>'.
  Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
  Info : clock speed 1000 kHz
  Info : NULINK is Nu-Link1
  Info : NULINK firmware_version(7313), product_id(0x40012009)
  Info : IDCODE: 0x2BA01477
  Info : NuMicro.cpu: hardware has 6 breakpoints, 4 watchpoints
  auto erase enabled
  Info : Device ID: 0x00d48750
  Info : Device Name: M487JIDAE
  Info : bank base = 0x00000000, size = 0x10080000
  Info : Nuvoton NuMicro: Sector Erase ... (0 to 8)
  Info : Nuvoton NuMicro: Flash Write ...
  Info : Have written 19%
  Info : Have written 39%
  Info : Have written 59%
  Info : Have written 79%
  Info : Have written 98%
  Info : Have written 100%
  wrote 36864 bytes from file nu-cmake-example.hex in 16.331968s (2.204 KiB/s)
  shutdown command invoked
  [100%] Built target nu-cmake-example.elf

• Run Debugger

  Click menu "Run" --> "Start Debuggging", the debugger will break at "main" function.

Test with GDB

Open one terminal to run OpenOCD:

cd $PROJ_ROOT  
openocd -f ./res/nulink.cfg -f ./res/numicroM4.cfg  

Open another terminal to run GDB:

cd $PROJ_ROOT  
gdb-multiarch ./build/nu-cmake-example.elf  

In GDB session, issue the following commands, it will break on main function:

```shell
target remote localhost:3333
set remotetimeout 20
set breakpoint pending on
monitor reset init
monitor halt
monitor flash write_image erase ./build/nu-cmake-example.hex
monitor reset init
tbreak main
continue
list
```

Reference

• VSCode Cortex-Debug Extension Wiki

• CMake separate flags for Assembler

gcc -c foo.S will run your asm through the C preprocessor (before feeding it to as) if the filename has a .S (capital S) extension, not for lower-case .s. If you want to override that, yes -x can be used, in this case -x assembler-with-cpp. (Not -x assembler, that's already the default for .s files). Use gcc -v foo.S to see what it runs.