onefinity-firmware/.pi/BUILD.md

# Onefinity CNC Firmware — Build, Flash & Backup

## Architecture Overview

The Onefinity controller is a **Raspberry Pi 2/3** (armv7l, Raspbian Stretch, Python 3.5) connected to an **ATxmega192a3u** AVR microcontroller over serial. The Pi runs a Tornado web server (`bbctrl`) that serves the UI and plans G-code motion. The AVR executes realtime step/direction pulses.

```
Browser ←WebSocket→ Pi (Tornado/Python) → GCode Planner → Serial → AVR → Stepper drivers
```

The firmware package (`bbctrl-X.Y.Z.tar.bz2`) contains:
- **Python backend** (`src/py/bbctrl/`) — Tornado web server, planner, state machine
- **Web frontend** (`build/http/`) — Pug/Stylus/Svelte compiled to static HTML/JS/CSS
- **AVR firmware** (`src/avr/bbctrl-avr-firmware.hex`) — realtime motion controller
- **gplan.so** (`src/py/camotics/gplan.so`) — CAMotics G-code planner (native ARM .so)
- **Install scripts** (`scripts/install.sh`, etc.)

## Prerequisites

- Docker (for the devcontainer build environment)
- The devcontainer image: `docker build -t onefin-dev -f .devcontainer/Dockerfile .devcontainer/`
- SSH access to the Pi: `ssh bbmc@10.1.10.55` (password: `onefinity`)

## Building

### Full build (frontend + AVR + package)

```bash
docker run --rm -v "$(pwd):/workspace" -w /workspace onefin-dev \
  bash -c 'make all && python3 ./setup.py sdist'
```

Produces: `dist/bbctrl-1.6.7.tar.bz2` (~3MB)

### What `make all` builds

| Component | Command | Output |
|---|---|---|
| Web frontend | `npm install`, pug/stylus/svelte compile | `build/http/` |
| AVR firmware | `make -C src/avr` (avr-g++) | `src/avr/bbctrl-avr-firmware.hex` |
| Bootloader | `make -C src/boot` | `src/boot/bbctrl-avr-boot.hex` |
| Power MCU | `make -C src/pwr` | `src/pwr/bbctrl-pwr-firmware.hex` |
| Jig firmware | `make -C src/jig` | `src/jig/bbctrl-jig-firmware.hex` |

### gplan.so — the critical gotcha

`gplan.so` is the CAMotics G-code planner compiled as a Python C extension. It **must be a 32-bit ARM binary** linked against **Python 3.5** to run on the Pi.

**Do NOT build gplan.so in the devcontainer.** The devcontainer runs arm64/Debian Bullseye with Python 3.9. The resulting `.so` will be the wrong architecture and wrong Python ABI. Cross-compiling with `CXX=arm-linux-gnueabihf-g++` also fails because SCons ignores CC/CXX env vars.

The correct file must be:
```
ELF 32-bit LSB shared object, ARM, EABI5  (linked against libpython3.5m.so.1.0)
```
If you see `ELF 64-bit LSB shared object, ARM aarch64` or `libpython3.9` — wrong.

**Option A: Build from source (recommended)**

Uses Docker's armv7 QEMU emulation on Apple Silicon. Requires a one-time
copy of Python 3.5 headers from the Pi (~1.7MB):

```bash
# One-time: grab Python 3.5 headers + lib from Pi
ssh bbmc@10.1.10.55 'tar czf - /usr/include/python3.5m \
  /usr/lib/arm-linux-gnueabihf/libpython3.5m.so*' > /tmp/pi-python35.tar.gz
```

Then build (takes ~30min under QEMU):

```bash
docker run --rm --platform linux/arm/v7 \
  -v "$(pwd):/workspace" -w /workspace \
  -v /tmp/pi-python35.tar.gz:/tmp/pi-python35.tar.gz \
  debian:bullseye bash -c '
    set -e
    tar xzf /tmp/pi-python35.tar.gz -C /
    apt-get update -qq && apt-get install -y -qq build-essential scons git \
      ca-certificates python3-dev libssl-dev libexpat1-dev libbz2-dev \
      liblz4-dev zlib1g-dev perl file
    ln -sf /usr/lib/arm-linux-gnueabihf/libpython3.5m.so.1.0 \
           /usr/lib/arm-linux-gnueabihf/libpython3.5m.so

    # Clone cbang + camotics at pinned commits
    mkdir -p /tmp/cbang && cd /tmp/cbang && git init -q
    git remote add origin https://github.com/CauldronDevelopmentLLC/cbang
    git fetch --depth 1 -q origin 18f1e963107ef26abe750c023355a5c40dd07853
    git reset --hard FETCH_HEAD -q

    mkdir -p /tmp/camotics && cd /tmp/camotics && git init -q
    git remote add origin https://github.com/CauldronDevelopmentLLC/camotics
    git fetch --depth 1 -q origin ec876c80d20fc19837133087cef0c447df5a939d
    git reset --hard FETCH_HEAD -q

    # Build cbang
    cd /tmp/cbang && scons -j2 disable_local="re2 libevent"
    export CBANG_HOME="/tmp/cbang"

    # Patch camotics (clamp div-by-zero in planner)
    P="/tmp/camotics/src/gcode/plan"
    mkdir -p /tmp/camotics/build && touch /tmp/camotics/build/version.txt
    for F in LineCommand.cpp LinePlanner.cpp; do
      for V in maxVel maxJerk maxAccel; do
        perl -i -0pe "s/(fabs\\((config\\.$V\\[axis\\]) \\/ unit\\[axis\\]\\));/std::min(\\2, \\1);/gm" $P/$F
      done
    done

    # Compile with Python 3.9 (SCons needs python3-dev to find headers)
    cd /tmp/camotics && scons -j2 gplan.so with_gui=0 with_tpl=0

    # Relink against Python 3.5m (the Pi target)
    g++ -o /workspace/src/py/camotics/gplan.so \
      -Wl,--as-needed -Wl,-s -Wl,-x -Wl,--gc-sections -pthread -shared \
      build/gplan.os -L/tmp/cbang/lib \
      build/libCAMoticsPy.a build/libCAMotics.a build/libDXF.a \
      build/libSTL.a build/libGCode.a \
      -lstdc++ -lutil -lm -ldl -lz -lcbang -lcbang-boost \
      -lssl -lcrypto -llz4 -lexpat -lbz2 -lcrypt -lpthread \
      -lpython3.5m build/dxflib/libdxflib.a
  '
```

Why the relink step: SCons compiles `.o` files that are Python-version-agnostic
(they only use `#include <Python.h>` which is ABI-compatible between 3.5-3.9
for the subset camotics uses). The only version-specific part is the final
`-lpython3.X` link. So we let SCons build with 3.9 (since it ignores overrides)
then relink the same objects against 3.5m.

**Option B: From official release**

```bash
curl -L https://github.com/OneFinityCNC/onefinity-firmware/releases/download/v1.6.6/onefinity-1.6.6.tar.bz2 \
  | tar xjf - --include='*/gplan.so' --strip-components=3 -C src/py/camotics/
```

**Option C: From a working Pi**

```bash
scp bbmc@10.1.10.55:/usr/local/lib/python3.5/dist-packages/bbctrl-*.egg/camotics/gplan.so src/py/camotics/
```

### bbserial.ko — kernel module

The `bbserial.ko` kernel module requires cross-compiling against the Pi's exact kernel headers (4.9.59-v7+). The `make pkg` target tries to build it but it's rarely needed — the Pi already has a matching `.ko` installed. The `install.sh` script skips it gracefully if the file is missing (`cp: cannot stat 'src/bbserial/bbserial.ko': No such file or directory`).

### AVR emulator (for local demo mode)

```bash
docker run --rm -v "$(pwd):/workspace" -w /workspace/src/avr/emu onefin-dev make
```

Produces `src/avr/emu/bbemu` — a native binary that emulates the AVR for demo mode.

## Flashing

### Via web API (recommended, machine must be running)

```bash
curl -X PUT \
  -H "Content-Type: multipart/form-data" \
  -F "firmware=@dist/bbctrl-1.6.7.tar.bz2" \
  -F "password=onefinity" \
  http://10.1.10.55/api/firmware/update
```

Or: `make update HOST=10.1.10.55 PASSWORD=onefinity`

### Via SSH (if web UI is down / crash-looping)

```bash
scp dist/bbctrl-1.6.7.tar.bz2 bbmc@10.1.10.55:/tmp/

ssh bbmc@10.1.10.55 'echo onefinity | sudo -S bash -c "
  systemctl stop bbctrl
  mkdir -p /var/lib/bbctrl/firmware
  cp /tmp/bbctrl-1.6.7.tar.bz2 /var/lib/bbctrl/firmware/update.tar.bz2
  /usr/local/bin/update-bbctrl
"'
```

### What happens during flash

1. `update-bbctrl` stops bbctrl, extracts tarball to `/tmp/update/`
2. `install.sh` runs:
   - Flashes AVR via `scripts/avr109-flash.py` (serial bootloader protocol)
   - `setup.py install --force` — installs Python package + frontend + gplan.so
   - Restarts `bbctrl` systemd service
   - May reboot if boot config or kernel module changed

### Recovery if flash breaks the Pi

If bbctrl is crash-looping after a bad flash:
1. SSH still works: `ssh bbmc@10.1.10.55`
2. Check the error: `sudo python3 /usr/local/bin/bbctrl 2>&1 | head -20`
3. Common fix: replace gplan.so with correct ARM binary (see above)
4. Nuclear option: restore from SD card backup (see below)

## Running locally (demo mode)

Run the full stack in Docker with the AVR emulator:

```bash
# Build everything first (make all + bbemu + gplan.so for arm64 devcontainer)
# Then:
docker run --rm -d --name onefin-demo \
  -v "$(pwd):/workspace" -w /workspace -p 8765:80 \
  onefin-dev bash -c '
    pip3 install -q tornado sockjs-tornado pyserial watchdog
    cp src/avr/emu/bbemu /usr/local/bin/
    pip3 install -q -e .
    exec bbctrl --demo --port 80 --addr 0.0.0.0 --disable-camera
  '
```

Note: demo mode needs its own gplan.so matching the container's arch (arm64 + Python 3.9). Build it with the gplan build procedure in the Makefile, or use the one already in `src/py/camotics/` if it matches.

Open http://localhost:8765 — full UI with emulated AVR.

## SD Card Backup & Restore

```bash
# Backup (streams raw dd from Pi, compresses locally with gzip, ~50 min)
./backup/onefinity-backup.sh backup

# Verify
./backup/onefinity-backup.sh verify backup/onefinity-20260430.img.gz

# Restore to local SD card
./backup/onefinity-backup.sh restore backup/onefinity-20260430.img.gz /dev/diskN
```

See `backup/onefinity-backup.sh` for details. Environment variables: `ONEFINITY_HOST` (default 10.1.10.55), `ONEFINITY_USER` (bbmc), `ONEFINITY_PASS` (onefinity).

## Pi Details

| | |
|---|---|
| Host | `10.1.10.55` |
| SSH user | `bbmc` |
| sudo password | `onefinity` |
| OS | Raspbian Stretch (Debian 9) |
| Kernel | 4.9.59-v7+ |
| Python | 3.5.3 |
| Arch | armv7l (32-bit ARM) |
| SD card | 30GB |
| Service | `systemctl {start,stop,restart,status} bbctrl` |
| Log | `/var/log/bbctrl.log` or `journalctl -u bbctrl` |
| Config | `/var/lib/bbctrl/config.json` |
| Uploads | `/var/lib/bbctrl/upload/` |
| Web root | `/usr/local/lib/python3.5/dist-packages/bbctrl-*.egg/bbctrl/http/` |
| AVR serial | `/dev/ttyAMA0` at 230400 baud |