| name | qspice-mixed-signal-dll |
| description | Author, scaffold, build, and validate QSpice `.DLL` custom-device blocks for mixed-signal C/C++ models. Use when adding a controller or behavioral block backed by compiled code, generating a C++ scaffold from a symbol, building the DLL, or checking that a symbol matches its source. |
| license | MIT |
| metadata | {"author":"qspice-mcp","version":"1.0"} |
QSpice: Mixed-Signal .DLL Custom Devices
QSpice runs compiled C/C++ models as .DLL custom-device blocks. This skill
covers the full loop: place the block, generate matching source, build it, and
prove the symbol and source agree.
When to use
- A circuit needs a digital controller, state machine, or behavioral block that
is easier to express in code than in SPICE primitives.
- You have a
.DLL symbol and need a C++ scaffold, or a source file and need to
verify it matches the symbol.
When NOT to use
- Pure analog authoring/placement →
qspice-getting-started and
qspice-schematic-layout.
- A simulation that runs but won't converge →
qspice-convergence-debugging.
Workflow
- Check support.
describe_mixed_signal_support to confirm which scaffold
generators and build toolchains (bundled DMC, MSVC cl, CMake) are available
on this machine.
- Place / shape the block.
add_dll_block to insert a block with starter
input/output pins; adjust the interface with add_dll_block_pin,
remove_dll_block_pin, and set_dll_block_pin_role (input vs output preset).
- Generate source.
scaffold_dll_device_from_symbol emits a C++ stub plus a
CMakeLists.txt next to the schematic, with the pin signature already wired.
Edit the generated .cpp with write_workspace_text_file.
- Build.
build_dll_device compiles the source to a .dll (prefers bundled
DMC, falls back to MSVC/CMake). See the C-Block Build Guide for prerequisites.
- Validate.
validate_dll_symbol_signature cross-checks the symbol's pins
against the source so the block and code can't silently drift.
- Simulate.
generate_netlist then run_simulation — DLL blocks are emitted
correctly (not as unresolved subcircuits) by the clean-room netlister.
Notes
generate_dll_variables produces .DLL variable declarations via the QUX
companion path when you need them.- The symbol is the contract: pin order/names in the symbol must match the
source's port list. Re-run
validate_dll_symbol_signature after editing either.
- If no toolchain is present,
build_dll_device reports a degradation rather than
guessing — install MSVC build tools or rely on bundled DMC.
Conventions
- Keep the
.cpp, CMakeLists.txt, and .qsch in the same workspace folder so
QSpice's Show Source and the build commands resolve relative paths.
- Validate before simulating; a mismatched signature fails confusingly at sim time.
