4-pump module

Rumtime

Rumtime is a modular cocktail execution engine: ingredients are registered as services, recipes are resolved at runtime, and beverages are dispensed through a scalable ESP32-powered pump architecture.

This repo holds Rumtime documentation, Phase 0 bench-rig firmware, and KiCad PCB specifications. CAD and full product firmware are still in progress. The v1 hardware design uses food-safe tubing, Kamoer KPHM100-class reversible peristaltic pumps, modular 4-pump cartridges, and an ESP32-S3 controller. Software stack direction (Cloudflare kiosk UI, ESP32 dispense engine) and locked firmware runtime model (ControlTask + command queue on FreeRTOS) are in docs/16-firmware-and-software-architecture.md. Kiosk UX and React + shadcn stack in docs/17-kiosk-ui-plan.md; production app at ui/kiosk/. Provisional device HTTP contract in docs/18-kiosk-device-api.md.

Current design snapshot

• Version 1 pump count: 8 installed pumps.
• Expansion target: 12 total pumps via one additional 4-pump module.
• Control platform: ESP32-S3 or similar ESP32 board, Wi-Fi only.
• Pump strategy: One reversible peristaltic pump per ingredient.
• Measurement strategy: Timed dispensing after calibration; load cell required for glass/ice detection, flow-gated pour start, and sanity checks.
• Carbonation: Do not pump carbonated mixers in v1. Software should instruct the user to top off manually.
• Cleaning: Moderate-effort cleaning with warm-water flush and Star San/session sanitizer workflow.
• Budget target: About $500 max for v1, excluding liquor and ingredients.
• Build style: Finished-looking countertop dispenser, with external bottles and replaceable tubing.

Document map

Design philosophy

Build the simplest version of Rumtime that can make repeatable drinks, clean up reasonably, and expand without rewiring everything. Avoid premature complexity such as inline flow meters, shared manifolds, fridge drilling, carbonated pumping, or fully custom embedded module networks until the basic 8-pump machine has been validated.

Current status

Next action: Fit-check/measure the assembled load-cell cantilever, then solder the bar to HX711 (E+/E−/A+/A−) and run Tests 7–9. Parallel: finish 4-pump PCB layout (silkscreen/placement). Schematic v1 is ERC-clean. Bar 75 mm, holes 5 / 15 / 59 / 69, M4 tapped — hardware/cad/refs/estardyn-load-cell.md. HX711↔MCU already wired (GPIO 8/9). Sessions: 06 (measure + print) · 07 (assembled, not measured).

Done so far: 8× correct 12 V HB pumps are on hand and the 2 wrong 24 V units were returned. P1 + P2 are bench-validated @ 1.75 ml/s; dual-pump ~0.4 A; anti-drip 100 ms; P2 sequential 50 ml target → ~45 ml (anti-drip); host CLI benchctl.py + proto=2 serial parser. The other 6 pumps still need incoming inspection and variance testing.

Decisions are locked in docs/12-phase-0-decisions.md (KPHM100-HBB10 pump, TB6612 breakout, ESP32-S3-DevKitC-1, KiCad for Phase 2 PCB).

First prototype goal

Validate the core liquid path with 2–4 pumps. Module schematic v1 is done (ERC clean). Layout/silkscreen in progress. Fab waits on DRC (I2C bring-up is Test 10 on the first board).

1. Dispense 15 ml, 30 ml, and 60 ml targets by time after calibration.
2. Validate flow-gated dispense vs timed-only on de-primed and post–anti-drip lines (Test 9) — v1 pour default, not a PCB gate.
3. Reverse briefly after pours to reduce drips; document sequential pour drift (Test 4b).
4. Flush simple syrup and grenadine adequately with warm water.
5. Confirm tubing and nozzles do not retain obvious flavor or clog during a normal session.
6. Confirm load cell detects glass, ice tare, flow onset, and no-flow conditions (Tests 7–9) — v1 pour, not a PCB gate.
7. I2C pump control is proven on the first assembled module (Test 10), not a pre-fab MCP23017 breakout.

After DRC, fabricate the 4-pump module (hardware/kicad/) and proceed to the finished enclosure.