STM32 Pinout Tool

A browser-based tool for automatic STM32 pin assignment using constraint-based solving. Define your peripheral requirements in a simple constraint language, and the solver finds optimal pin assignments across multiple MCU variants.

Features

• 18 solver algorithms -- backtracking, two-phase, cost-guided, AC-3, dynamic MRV, randomized restarts, diverse instances, priority backtracking, priority two-phase, priority diverse, priority group, MRV group, ratio MRV group, hybrid, conflict-directed (CBJ + dom/wdeg), CEGAR instance-refinement, LNS repair (min-conflicts), and adaptive portfolio
• Parallel multi-solver -- run multiple solvers simultaneously and merge results
• Visual package viewer -- interactive canvas with zoom, rotation, pin assignment popup, and signal search
• Multiple package types -- LQFP, BGA, and WLCSP support with correct ball/pin rendering
• Logical / physical pin model -- handles PINREMAP variants on C0/F0/G0/U0, multi-bond pads on UFQFPN20 / WLCSP, and _C analog-switch siblings on H7. The solver locks every co-bonded sibling when one is assigned, so cross-port pinouts never collide on a shared package pad.
• Reserve by GPIO name OR package position -- reserve: PA0, reserve: 11, reserve: A1 are all valid; position-based reservations lock every logical bonded to that pad.
• Remote MCU catalogue -- point the Data Manager at a hosted vendor JSON catalogue (index.json + per-die files); browse with a live filter overlay, or let mcu: filters auto-fetch matching dies during solve. Fetches are cancellable via the solver Abort button. Cache is in-memory (10 dies / 500 KB), cleared on reload.
• Cost-optimized solutions -- ranked by pin count, port spread, clustering, proximity, and more
• Multi-MCU search -- solve across multiple MCU variants with mcu:, package:, ram:, rom: filters
• Grouped solution browser -- solutions grouped by peripheral assignment, keyboard-navigable
• Pin group highlighting -- hover/click port names or peripheral instances to highlight pins on the viewer
• Project management -- save/load projects, store MCU data in browser localStorage
• DMA stream assignment -- dma() constraints with automatic stream exclusivity checking (STM32F4 fixed mapping + STM32H7 DMAMUX)
• CubeMX .ioc import -- import pin assignments from STM32CubeMX project files
• Editable macro library -- customize and extend the standard library macros via Data Manager
• Common-error lint -- editable library of "confusable" signal names (miso/mosi, tx/rx, ch1..4) that flags likely name swaps directly in the editor with yellow squiggles + minimap markers
• Compare solutions -- Ctrl/Cmd-click multiple project solutions to overlay them in the package viewer; matching pins render normally, divergent pins pulse through one color per solution and expose per-solution mappings in the tooltip
• Custom export functions -- user-defined JavaScript export functions for any output format
• Interactive tutorial -- guided tour for first-time users
• Dark mode -- full light/dark theme support

Getting Started

npm install
npm run dev

Open http://localhost:5173 in your browser.

Loading MCU Data

1. Download MCU XML files from STM32CubeMX (found in the db/mcu/ folder of the CubeMX installation)
2. Drag and drop the .xml or .ioc file onto the app, or click Import

Writing Constraints

Enter constraints in the editor panel. A minimal example:

port CMD:
  channel TX
  channel RX

  config "UART":
    TX = USART*_TX
    RX = USART*_RX
    require same_instance(TX, RX)

Press Ctrl+Enter or click Solve to find pin assignments.

Signal Search

Use the search field in the package viewer toolbar to find pins by signal pattern:

• TIM*_CH1 -- all timer channel 1 pins
• ADC*_IN[1-4] -- ADC inputs 1-4
• PA0 -- specific pin
• SPI -- substring match on any SPI signal

Exporting

Click Export in the viewer toolbar to choose a format:

• PNG -- raster image of the current canvas view
• SVG -- vector graphic, ideal for documentation and scaling
• Text -- copy pin assignment table to clipboard
• JSON -- structured pin assignment data
• Custom -- user-defined JavaScript export functions (manage via Data Manager)

Documentation

See doc.md for the full constraint language reference, practical examples, and detailed feature documentation.

Tech Stack

• TypeScript, Vite
• Canvas 2D rendering
• Web Workers for parallel solver execution
• Zero runtime dependencies

Build

npm run build    # production build to dist/
npm run dev      # development server with HMR

Known Limitations

Data quality (working on it)

Some data in the remote repo is parsed from datasheets and not imported from official ST XML files. There will be bugs.

Constraints syntax (it's a feature not a bug, won't fix)

The constraints language was build around some personal ideas about embedded design (e.g. peripheral instances are exclusive per port). It can't express all possible requirements.

Vendor lock-in (maybe later)

Right now only cpu data for the STM32 lineup is available, but most of the code base is vendor agnostic. The data format specification is available and the remote url is configurable. The format might change in the future to support new features or other vendors.

Vendor specific quirks (working on some)

Some special cases are not known or ignored by the solvers.

• STM32H7 direct pins can be connected to the corresponding base pin via an analog switch. Currently the solver will not assing any alternate function to a direct pin.
• Some STM32 peripherals allow pinswaping (e.g. UART_TX <-> UART_RX) or simmilar features (e.g. half duplex TX/RX on the same pin). This is not represented in the data.

CubeMX export (won't fix for now)

CubeMX .ioc files need more information to be valid (e.g. peripheral and clock settings). This data is currently not available.