Web Debug (browser UI)

cmsis-dap-cli web starts a local Web Debug server that exposes the same debug engine as a browser-based Debug Workspace — connect to a CMSIS-DAP probe, inspect registers / memory / peripherals, set breakpoints, watch variables live, read RTT / EVR output, disassemble, inspect the call stack and locals (DWARF), and program flash — all without Keil / IAR / Eclipse / VS Code.

Start

cmsis-dap-cli web

By default the server binds 127.0.0.1:8080 and opens a single-page application. Options:

All other global options (--target, --target-yaml, --flm, --probe-id, --svd, --elf, --protocol, --speed-khz, --under-reset, --core-index) are honoured as defaults for the web session.

Example for a custom chip defined by a Keil FLM:

cmsis-dap-cli web --target-yaml target/demo.yaml --probe-id <serial> --allow-destructive

Workspaces

• Debug — Dockable panels: Target/Symbols, Code/Disassembly, CPU Registers, Watch/Live Watch, Memory, Peripheral (SVD), Breakpoints, Call Stack, Locals, RTT, EVR, SWO and Console. Quick Debug and Full Debug are layout presets of the same workspace; the layout is persisted in the browser.
• Flash — drop a BIN/HEX file, analyse it (address ranges), then Erase / Program / Verify / Reset / Run with live progress. Flashing is destructive and always requires an explicit confirmation.

Highlights

• Symbols → Watch / Breakpoint — upload an ELF/AXF (debug info only, never flashed), search functions/variables, drag a symbol into Watch, or set a breakpoint by symbol name.
• Live Watch — variable values stream while the target runs; pick a refresh rate per item (50 ms … 1 s). Register-backed items are only read while halted.
• Peripheral explorer — upload an SVD file, browse registers with bit-field decode, and periodically refresh only the registers you monitor.
• Call Stack + Locals — real DWARF CFI unwinding and DWARF variable evaluation (types: base/pointer/typedef/struct/array/enum). Frames that have no unwind info, or values that cannot be read, are reported honestly (“unavailable”) — never fabricated.
• Expression — evaluate C-like expressions over symbols, registers ($pc, $sp) and memory (*(0x20000000)).
• Fault — when the core halts, CFSR/HFSR/DFSR/MMFAR/BFAR are shown and a Fault banner appears if any are set.
• Command Palette — Ctrl+Shift+P to run common commands.

WebSocket events

The UI receives incremental events over /ws: target_state_changed, live_watch_value_changed, peripheral_value_changed, rtt_output, evr_event, flash_progress, flash_complete, probe_lost, and more. probe_lost invalidates the session immediately (a USB removal never leaves the UI “connected”).

Security

The server binds to 127.0.0.1 by default and exposes the debugger only locally. Destructive operations (flash) are gated behind --allow-destructive and require an explicit confirmation in the UI.