ALPACA 2.0

© Copyright Delft University of Technology, CC BY 4.0.

ALPACA (Advanced Learning Platform for Analog Circuits and Automation) is a device built on RP2 and MicroPython and equipped with several digital tools to be a guide in introduction to digital systems and electronics for NB2420 Electronic Instrumentation course of TU Delft.

ALPACA splits work across two Picos:

• Student Pico: the board a student writes code on via Belay. It exposes a tiny RPC client so student programs can ask the Helper to do things. Student Pico is equiiped with a double channel DAC.

• Helper: a self-contained instrument. It drives an LCD and runs a set of measurement screens (voltmeter, component/resistance tester) that the user can cycles through. It also answers commands sent by the Student over a UART link.

A host-side CLI (alpaca) handles flashing your code onto the boards and opening a serial REPL, so you never have to manage USB ports by hand.

The Student and Helper talk over UART0 with a crossover wiring and a shared ground:

  Student GP00 (TX) ──► Helper GP13 (RX)
  Student GP01 (RX) ◄── Helper GP12 (TX)
  GND ◄──────────────► GND

Repository layout

📁 alpaca folder contains the libraries for Picos. 📁 src/alpaca contains the desktop-side library and the ALPACA CLI for managing the boards (src/alpaca/cli). It is published on PyPI as alpaca2, but the import name and the command stay alpaca, so installed users write from alpaca import list_boards.

alpaca/common is copied alongside alpaca/student or alpaca/helper onto each board at sync time, which is why on-device imports are flat (from command import ..., from link import ...).

Therefore if the folders are like this

📁 alpaca/
  📁 common/
    📄 A.py
  📁 student/
    📄 B.py
  📁 helper/
    📄 C.py

using alpaca sync will copy the files to the root as:

🍓 HelperPico
  📄 A.py
  📄 C.py

🍓 StudentPico
  📄 A.py
  📄 B.py

Setup

uv sync

This installs the project and exposes the alpaca command. Outside a checkout, install the published package instead:

pip install alpaca2   # or: uv tool install alpaca2

Usage

Sync your code onto the boards

uv run alpaca sync

This discovers connected Picos, copies the common + student/helper code onto each, and soft-resets them. To drop into a REPL on one board right after syncing:

uv run alpaca sync --connect student

Open a serial REPL

uv run alpaca connect student   # or: helper

Picking a board

The first time the CLI needs a board it lists the connected Picos in a terminal menu. Hovering an entry lights that board's onboard LED so you can tell which is which, and you can choose to remember the selection — it's cached per role under .alpaca/ so later runs skip the prompt.

Building

The repository workflow should build and publish stubs, and assemble firmware images on creation of a version tag.

git tag v1.0.0
git push origin v1.0.0

The MicroPython version for firmware is set inside the build-firmware.yml (currently 1.28.0).