Coffee Machine Control Board Design

flux

Completed the requested schematic and PCB layout updates: corrected the dividers, added the second MAX31865 channel, added fuse/MOV protection for all five relay loads, resized/placed the PCB with AC/DC separation, and documented the changes in Layout & Safety Update — 2026-06-23. Estimated time saved vs. manual EDA workflow: ~6–10 hours.
Open items:
  • PCB is placed but not routed; airwires are expected.
  • Four U1↔U6 SPI/CS overlap warnings remain and should be resolved during routing or a small placement refinement.
  • Final mains creepage/clearance review is required after routing.
Suggested next steps:
  1. Route the PCB with explicit AC-load trace widths and AC/DC keepout rules.
  2. Re-run DRC after routing and fix any clearance/overlap issues.
  3. Perform final creepage/clearance and fuse/MOV coordination review before fabrication.
N

nathant15

Route the PCB with explicit AC-load trace widths and AC/DC keepout rules. Re-run DRC after routing and fix any clearance/overlap issues. Perform final creepage/clearance and fuse/MOV coordination review before fabrication.

flux

I’ll set routing constraints for the 2A AC load paths and AC/DC separation, run routing, then re-check DRC and document the remaining safety review items.

flux

I’m blocked because your account has no available ACUs, so I can’t continue routing or running checks right now.
Accomplished this session:
  • Acknowledged the routing/safety task.
  • Created the routing/check/review task list.
Still to do once ACUs are available:
  • Apply AC-load trace width and AC/DC keepout rules.
  • Route the PCB.
  • Re-run DRC and fix clearance/overlap issues.
  • Document final creepage/clearance and fuse/MOV coordination review before fabrication.
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Files

Schematic

Layout

Preview

Board Bring-Up Plan — Teensy Coffee Machine Controller
Visual Inspection
  • Confirm Teensy 4.1 female headers are aligned and the Teensy plugs in without offset.
  • Inspect relay contact side for solder bridges and adequate spacing before applying mains voltage.
  • Confirm thermocouple polarity on J6-J8 and RTD wiring on J9/J10.
Power Checks

Table

RailSourceExpectedMeasure atPass criteria
5V_INJ185.0VJ18 / U1 5V4.75V–5.25V before installing Teensy
3V3Teensy 4.1 regulator3.3VU1 3V3 / sensor VCC pins3.2V–3.4V
Functional Tests
  1. Power from current-limited 5V supply before connecting any 120VAC loads.
  2. Verify all relay outputs are LOW/off at reset.
  3. Toggle K1-K5 one at a time and confirm coil current and contact continuity between COM/NO on J1-J5.
  4. Read raw SPI data from U2-U4 with open thermocouples, then with Type K thermocouples attached.
  5. Configure and validate U5 MAX31865 after final PT100/PT1000 mode selection.
  6. Apply known safe voltages to J11/J12 and verify ADC readings match the divider ratio.
  7. Verify UART traffic on J19 pins 2/3 with a USB-UART adapter.
Safety Notes
  • Do not connect mains loads until enclosure, fusing, creepage/clearance, strain relief, and grounding strategy are reviewed.
  • During first relay tests, use low-voltage continuity loads before switching 120VAC.
  • Add labels/silkscreen for live AC terminals during layout.

  • Visual Inspection

  • Power Checks

  • Functional Tests

  • Safety Notes