qte77 pushed to refs/heads/main at Lambda-Biolab/i3mega-pipettebot
Commits on May 8, 2026
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docs: add Path 2 (SBC-on-printer) deployment guide (#21)
Adds docs/sbc-deployment.md describing how to replace the laptop tether with a small Linux board (Raspberry Pi Zero 2 W or Pi 4) zip-tied to the printer chassis. Both the i3 Mega and the dPette are USB devices (CH340/CP2102N and CP2102 respectively) — neither is a USB host. Plugging them directly together does not work; see issue #18 and the existing hardware.md discussion. The two paths that make the printer + pipette self-contained are: Path 2 (this doc): mount a Pi as USB host for both. No firmware patch, no soldering, no warranty voided. Cost: ~$25-40. Replaces laptop tether but does not unlock SD-card autonomy. Path 3: UART tap inside the dPette + level shifter + Marlin patch (M820 pass-through). Tracked in AGENT_REQUESTS.md as Stage 2a + level-shifter PCB. Only path that lets host-less SD-card runs actually pipette. The doc covers BOM, headless RPi OS Lite setup (rpi-imager + uv + git clone + make init), wiring (with a powered-hub note for Pi Zero 2 W), port disambiguation via /dev/serial/by-id/, an optional systemd unit (with explicit no-auto-start-of-motion warning for v0), and an explicit list of what Path 2 doesn't unlock (SD autonomy, hot-swap dPette, no-PC-at-all). Status: DRAFT — graduates to STABLE after first physical Pi-on-Mega build, mount STL committed under hardware/, and arm64 CI matrix addition. The 5 backlog items are listed at the bottom of the doc. Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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