Placement was inspected, but no project mutations were made.
Board: 21 × 10 mm, custom 4-layer, 1.60 mm thick.
Connector J9: top side at approximately (−2.8, +1.45) mm; footprint/courtyard is about 14.9 × 8.5 mm. This connector alone cannot fit a 10 × 8 mm board, so the current 21 × 10 mm outline cannot safely be reduced to the target without selecting a smaller connector.
Microphone MK1: bottom side at (+7.6, 0) mm. The enclosure inlet datum is therefore the centered through-board acoustic hole at (+7.6, 0) mm, currently 0.8 mm diameter.
Port direction: the INMP441 is a bottom-port microphone—its acoustic opening faces the PCB. The datasheet recommends an aligned PCB hole of 0.5–1.0 mm, so the present 0.8 mm hole is appropriate.
Decoupling: C11 is 100 nF, matching the datasheet requirement, but the datasheet requires it close to VDD with short, same-layer, via-free connections.
Physical blocker: the actual INMP441 package is 4.72 × 3.76 × 1.00 mm, while the current MK1 layout bounds appear only about 3.55 × 3.26 mm. Its SMD pads also appear fixed to Top copper while MK1 is placed on Bottom. The footprint therefore needs correction and re-verification before placement can be approved or C11 safely repositioned.
Checks: no overlap, bounds, keepout, edge, or neckdown placement errors were reported. Seven expected airwires remain; no routing was performed. A board-density warning remains.
The board is not ready for routing until the MK1 footprint/layer issue is corrected and the connector-versus-10 × 8 mm size conflict is resolved. The independent review completed, but I could not retrieve and reconcile its final report because execution stopped when your ACUs ran out.
Unpowered inspection: verify J2 battery polarity against the selected protected pack, USB shield/ground, TVS orientation, charger/regulator exposed pads, ESP32 antenna keepout, and clean/unblocked microphone port.
Resistance checks: measure GND to TP1/TP2/TP3/TP4/TP5 before applying power; investigate shorts or unexpectedly low resistance.
USB current-limited power: begin at 5 V / 100 mA with no battery. Verify TP1 raw VBUS, TP2 protected VBUS, and TP4 BQ24074 OUT. Increase the bench limit only after stable operation. The charger is strapped to USB500 mode (500 mA maximum input).
3V3 rail: close SW7 and verify TP5 is 3.3 V. Capture startup, ripple, and radio-load transient droop. Open SW7 and verify the regulated rail shuts down while charging/power-path circuitry remains available.
Programming: use J3 pinout 1=3V3, 2=GND, 3=ESP TX/adapter RX, 4=ESP RX/adapter TX, 5=EN, 6=GPIO0. Hold GPIO0 low while toggling EN to enter download mode.
Inputs: verify BTN_1..BTN_4 and both encoder A/B/push sets are inactive high and pull low when actuated. Confirm direction and debounce.
Microphone: probe TP12 SCK, TP13 WS, and TP11 SD. Verify 16 kHz mono left-slot capture, clock ratio, bit alignment, speech level, and noise floor.
Charger status: verify GPIO36/CHG_ACTIVE_N and GPIO35/CHG_PGOOD_N. Confirm correct active-low behavior with USB absent, valid USB present, charging, and charge complete.
Battery/charging: attach the selected protected one-cell LiPo only after polarity verification. Check TP3 battery voltage, charge current, termination, system/battery switchover, operation while charging, and charger thermal rise. Active HFP may reduce or pause charge current because the USB input limit is 500 mA.
Bluetooth: test HID alone, HFP HF alone, then simultaneous HID + HFP on Windows and macOS. Log mSBC/CVSD negotiation, reconnect behavior, range, audio dropouts, and HID latency.
Power profiling: measure power-off, boot, connected idle, HID activity, HFP audio, radio peaks, charging, and sleep. Update the Power Budget with measured typical, peak, and transient-duration values.
Test-point map
Table
Test point
Net
TP1
USB_VBUS_RAW
TP2
USB_VBUS_PROTECTED
TP3
BAT_POS
TP4
SYS_OUT
TP5
3V3
TP6
GND
TP7
ESP_EN
TP8
ESP_GPIO0_BOOT
TP9
UART0_TX
TP10
UART0_RX
TP11
MIC_I2S_SD
TP12
MIC_I2S_SCK
TP13
MIC_I2S_WS
Stop conditions
Stop for reversed battery polarity, rail overshoot, sustained charger/regulator heating, 3V3 droop or reset during radio activity, unexpected USB draw above 500 mA, or battery current outside the revised power-budget envelope.