pico-mcp

A lean MCP (Model Context Protocol) server for PicoScope 5000A USB oscilloscopes (developed and verified on a 5442B). It lets an LLM/agent drive the scope: discover the device, configure channels, run the built-in signal generator, capture blocks, take measurements, and sweep a frequency response.

Built because the existing third-party server was too buggy (a find_all_units() discovery that crashes the process on the ps6000a driver, ctypes.byref errors on GetUnitInfo, a device-handle leak, and an is_connected check on a field that is never set). This server talks to the ps5000a driver directly; every code path was verified against real hardware.

macOS Apple Silicon note (important)

Changed 2026-08-01 — no Rosetta needed any more. PicoScope 7 T&M 7.2.24 ships arm64 libraries. Earlier versions were x86_64, which is why this project used to require a Rosetta venv. If you followed the old instructions, see Migrating from the Rosetta setup below — it fails in a confusing way, because the old x86 venv keeps working right up until the app is updated.

There is still one thing to do: PicoScope no longer installs a separate PicoSDK.framework, so ctypes.util.find_library("ps5000a") finds nothing. Link the libraries from inside the app into ~/lib, which is on Python's default macOS library search path (DEFAULT_LIBRARY_FALLBACK in ctypes.macholib.dyld) — no sudo, and no DYLD_LIBRARY_PATH in your MCP config, which matters because the app path contains both a space and an &.

On Windows/Linux with a natively installed PicoSDK, none of this applies.

Related MCP server: keyscope-mcp

Setup

git clone https://github.com/Schimmilab/pico-mcp.git
cd pico-mcp

python3 -m venv .venv
.venv/bin/pip install -e .

macOS only — make the driver discoverable (symlinks, so a PicoScope update carries over):

SRC="/Applications/PicoScope 7 T&M.app/Contents/MonoBundle"
mkdir -p ~/lib
ln -sfn "$SRC/libps5000a.dylib"   ~/lib/libps5000a.dylib
ln -sfn "$SRC/libps5000a.2.dylib" ~/lib/libps5000a.2.dylib   # libps5000a.dylib links against this

python3 -c "import ctypes.util; print(ctypes.util.find_library('ps5000a'))"
# -> /Users/<you>/lib/libps5000a.dylib

Quick hardware test (close the PicoScope desktop app first — a scope can only be opened by one program at a time):

.venv/bin/python -c "from pico_mcp.scope import probe_devices; print(probe_devices())"
# -> [{'model': 'PS5000A', 'variant': '5442B', 'serial': '...'}]

Verify against a connected scope, not just an import. import pico_mcp.server succeeds even when no driver can be loaded — it says nothing about whether the thing works.

Migrating from the Rosetta setup

rm -rf .venv-x86            # x86 Python cannot load the new arm64 libraries
python3 -m venv .venv
.venv/bin/pip install -e .
# then the ~/lib symlinks above, then re-register (note: no --env any more)
claude mcp remove pico
claude mcp add pico --scope user -- /ABSOLUTE/PATH/TO/pico-mcp/.venv/bin/pico-mcp

Register in Claude Code

claude mcp add pico --scope user -- /ABSOLUTE/PATH/TO/pico-mcp/.venv/bin/pico-mcp

(Replace /ABSOLUTE/PATH/TO/ with your clone location.) A newly registered server is only picked up by a new Claude Code session — the MCP connections are fixed at session start.

Tools

Example: measuring a transformer

Connect AWG/GEN → channel A (input) → device-under-test → channel B (output), enable both channels, then ask the agent to run a frequency_sweep. The server drives each frequency, captures both channels and reports the gain B/A — yielding the −3 dB bandwidth, pass-band flatness and any resonances. (This was the first real use: characterising a 1:1 audio isolation transformer — flat 17 Hz–1.4 MHz, one mild resonance at 380 kHz.)

Notes

• Close the PicoScope desktop app before connecting — exclusive device access.

• capture_block returns a downsampled waveform (no megasample dumps); measurements are computed from the full-resolution data.

• Code changes take effect after the MCP host reloads the server (e.g. restart the session). The driver layer can be tested without a reload by running it directly in the venv.

License

MIT

Maintainer

Schimmi — https://schimmilab.de Issues und Pull Requests willkommen.