Coffee Machine Control Board Design

Worked for 29 mins

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:

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.

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.

Thought for 5 sec

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.

Thought for 10 sec

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.

Check ACU options

Save requirements note

List manual rules

Find rule settings

Files

Schematic

Layout

Preview

Safety Analysis — Teensy Coffee Machine Controller

Scope

This board switches 120VAC loads up to 2A through relay contacts and controls heating-related coffee machine functions. This is a preliminary design-stage safety note.

Main Hazards

Table

Hazard	Source	Preliminary mitigation
Electric shock	120VAC on relay contacts and terminal blocks	Maintain creepage/clearance in layout, use enclosure and strain relief, label live terminals
Fire / overheating	Relay load fault or undersized wiring	External fuse/breaker appropriate to load, terminal/trace sizing for >=2A, thermal testing
Uncommanded heating	Firmware fault or relay welded closed	Default relays off at reset, consider independent thermal cutoff/thermostat in final appliance wiring
Sensor misread	Thermocouple/RTD wiring fault	Firmware fault detection, plausibility limits, open-sensor detection, fail-safe relay shutdown

Open Safety Items Before Manufacturing

Confirm relay contact ratings and PCB creepage/clearance for the exact pollution degree/material group.
Add fusing/protection strategy for each AC load or upstream branch circuit.
Decide if opto-isolation is required between logic and relay/field wiring for the final appliance architecture.
Validate firmware failsafe behavior for sensor faults and MCU reset.

Scope
Main Hazards
Open Safety Items Before Manufacturing