ARM LiveWatch

Real-time variable monitoring WITHOUT halting the CPU — the missing Keil Live Watch experience for VS Code.

Unlike the built-in Debug Watch that requires pausing your program, ARM LiveWatch continuously reads MCU memory while your firmware keeps running — just like Keil's Live Watch.

Why This Extension?

Supported Chips

Any ARM Cortex-M chip supported by OpenOCD:

If your chip works with OpenOCD + arm-none-eabi-gdb, it works with ARM LiveWatch.

Features

• Live variable watch — continuously reads SRAM without halting the CPU
• Struct/class expansion — auto-parses nested structs, unions, and arrays into a tree view
• Enum name display — maps raw enum values to their symbolic names
• Pointer chain tracking — supports ptr->field expressions with automatic dereference
• Runtime value editing — double-click any leaf value to write directly to MCU memory
• Multiple display formats — right-click to switch between Auto / Hex / Decimal / Float / Binary
• Auto ELF detection — finds your ELF from launch.json (cortex-debug) or build/ directory
• Auto reconnect — reconnects to OpenOCD automatically after disconnection
• Change highlighting — yellow flash animation when values change

Quick Start

Prerequisites

1. arm-none-eabi-gdb — for parsing DWARF debug info from your ELF
2. OpenOCD — running and connected to your board (default TCL port: 6666)

Usage

1. Install the extension
2. Start OpenOCD with your board connected
3. Open the ARM LiveWatch tab in the VS Code bottom panel
4. Type a variable name and press Enter — done!

The ELF file is auto-detected from your launch.json cortex-debug config or build/ directory.

Examples

speed_pid              → watch a global struct, expand to see all fields
motor.output           → watch a specific struct member
ins_topic.data_->euler → follow a pointer chain

Settings

Tips

• Right-click a row to change display format or delete the watch
• Press Delete key to remove the selected watch
• Works alongside Cortex-Debug — use both at the same time

How It Works

1. Symbol resolution — arm-none-eabi-gdb -batch reads DWARF info from ELF to get variable addresses and type layouts
2. Memory reading — OpenOCD TCL interface (mdw command) reads MCU SRAM in real-time
3. Value formatting — displays values based on type info (float / int / enum / bool / pointer)

License

MIT