Project Started

flux

Revised the design around a TCA8418 keypad scanner: all 20 diodes were removed, the 5×4 matrix now connects only to the scanner, and I²C, INT, RESET, decoupling, and required pull-ups were added. The potentiometer and latching-switch sections remain intact; ERC and legibility checks are clean.

Generated image

The project specification, firmware guide, and bring-up plan were also updated for the TCA8418 architecture. The next priority is reviewing the schematic before starting PCB placement.
R

rainbothjoshua

flux

I’ll inspect the board state first, determine whether placement, routing, or both are incomplete, then run the required auto-layout steps and validate the applied result.

flux

Placement was required—the prior components were mostly off-board—and is now applied as a 5×4 key grid with grouped scanner, controls, and MCU. The board passed routing preflight, so full trace routing is now running.

flux

Both placement and routing were needed.
  • Re-placed all 44 components inside the 160 × 100 mm, 4-layer board.
  • Arranged the 20 keys into a 5×4 grid and grouped the TCA8418, ESP32-S3, analog controls, latching switches, and support passives.
  • Cleared placement overlaps and out-of-bounds errors in the placement validation.
  • Generated 23 fine-pitch neckdowns for the TCA8418.
  • Routing preflight passed with only an informational via-at-SMD adjustment for the TCA8418 exposed pad.
  • Started auto-routing; the partially applied result currently has approximately 126 airwires remaining.
Routing is not complete. The existing auto-route job is paused and can be resumed without discarding its progress. Execution stopped because your ACUs ran out.
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Files

Schematic

Layout

3D View

Board Bring-Up Plan
Pre-Power Checks
  1. Confirm no continuity short between 3V3 and GND.
  2. Confirm no control net is connected to 5 V or any 12 V source.
  3. Verify U2 VCC and C3 connect to 3V3; U2 GND, exposed pad, and C3 return connect to common GND.
  4. Verify SDA, SCL, KEYPAD_INT, and KEYPAD_RST each have their specified pull-up.
  5. Verify ROW1..ROW5 and COL1..COL4 connect only between the 20 switches and U2; verify no matrix diodes remain.
  6. Verify SW21/SW22 unused throws are no-connect and R5/R6 are populated 10 kΩ pull-ups.
Power Checks
  1. Connect only the DevKit onboard USB connector.
  2. Measure approximately 3.3 V from the 3V3 header to GND and at U2 VCC.
  3. Verify KEYPAD_INT, KEYPAD_RST, I2C_SDA, I2C_SCL, LATCH1, and LATCH2 idle HIGH.
  4. Verify both potentiometer endpoints are 3V3 and GND.
I2C and Reset Checks
  1. Assert KEYPAD_RST low for at least 120 us, release, then wait at least 120 us.
  2. Scan the I2C bus and confirm the TCA8418 acknowledges at its datasheet-defined address.
  3. Read a known identification/default register value before enabling keypad interrupts.
  4. Configure ROW0–ROW4 and COL0–COL3 as the 5×4 keypad matrix, then enable debounce, event FIFO, and interrupt reporting.
Functional Tests
  1. Press and release every key individually; confirm one correct event for each of the 20 matrix coordinates.
  2. Confirm KEYPAD_INT asserts low when events are queued and releases after firmware drains/clears the event condition. INT is active-low open-drain.
  3. Test representative multi-key combinations and verify the event FIFO preserves press/release ordering without phantom reports.
  4. Close each latch and verify only its associated input reads LOW; open must read HIGH from the external pull-up.
  5. Sweep each potentiometer and verify stable ADC readings across the usable range with the 100 nF filters.
Pass Criteria
  • U2 is reachable over I2C after reset.
  • All 20 keys generate unique, correctly mapped press and release events.
  • Interrupt/event-buffer service operates without stuck-low INT or lost events.
  • Analog channels are stable and both latching inputs report open HIGH / closed LOW.
  • No GPIO or control node exceeds the 0–3.3 V range.

  • Pre-Power Checks

  • Power Checks

  • I2C and Reset Checks

  • Functional Tests

  • Pass Criteria