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title Electronics
icon bolt
description PCB design files for the Omi mainboard, charger board, and flexible PCB — Altium source, Gerber files, and schematics.

Board Overview

The Omi uses three interconnected PCBs:

Board Function Latest Version
Mainboard nRF5340 SoC, nRF7002 Wi-Fi, microphones, IMU, flash, battery management v1.2
Charger Board Magnetic dock with pogo pins, USB-C power, ESD protection v1.0
FPC Flexible cable connecting mainboard to charging contacts v1.0
The main PCB carries all active electronics. 
**Key ICs:**

| IC | Function |
|----|----------|
| nRF5340-CLAA | Dual-core Bluetooth LE SoC (application + network cores) |
| nRF7002-CEAA-R7 | Wi-Fi 6 companion IC |
| CSNP4GCR01-DPW | 8GB NAND Flash |
| LSM6DS3TR-C | 6-axis IMU |
| BQ25101YFPR | Li-Ion/Li-Poly battery charger |
| TPS628438YKAR | DC-DC buck converter |
| 2x MMICT5838-00-012 | TDK T5838 PDM microphones |

**Files:**

| File | Description |
|------|-------------|
| [`schematic.pdf`](https://github.com/BasedHardware/omi/blob/main/omi/hardware/consumer/electrical/mainboard/schematic.pdf) | Full schematic |
| [`gerbers/`](https://github.com/BasedHardware/omi/tree/main/omi/hardware/consumer/electrical/mainboard/gerbers) | Gerber + drill files for PCB fabrication |
| [`altium/`](https://github.com/BasedHardware/omi/tree/main/omi/hardware/consumer/electrical/mainboard/altium) | Altium Designer source project |

<Warning>
The nRF5340 (WLCSP-95, 4.4x4.0mm) and nRF7002 (WLCSP-81, 3.75x3.4mm) are fine-pitch wafer-level packages. Requires stencil + solder paste + reflow. Do not hand solder.
</Warning>
Magnetic charging dock with USB-C input. 
**Key ICs:**

| IC | Function |
|----|----------|
| TPS25200DRVR | eFuse power manager (6.5V, 2.8A) |
| TPD1E10B06DPYR | ESD protection diode |

**Files:**

| File | Description |
|------|-------------|
| [`schematic.pdf`](https://github.com/BasedHardware/omi/blob/main/omi/hardware/consumer/electrical/charger-board/schematic.pdf) | Schematic |
| [`gerbers/`](https://github.com/BasedHardware/omi/tree/main/omi/hardware/consumer/electrical/charger-board/gerbers) | Gerber files |
| [`altium/`](https://github.com/BasedHardware/omi/tree/main/omi/hardware/consumer/electrical/charger-board/altium) | Altium source |

<Tip>The charger board is the simplest of the 3 — a good starting point if you're new to PCB assembly.</Tip>
Connects the mainboard to the charging contact ring via a board-to-board connector. 
**Key Components:**

| Component | Description |
|-----------|-------------|
| ST-BTB-K3570606M | BTB male connector (6+4P) |
| Charging contact ring | D9.9mm |

**Files:**

| File | Description |
|------|-------------|
| [`schematic.pdf`](https://github.com/BasedHardware/omi/blob/main/omi/hardware/consumer/electrical/fpc-board/schematic.pdf) | Schematic |
| [`gerbers/`](https://github.com/BasedHardware/omi/tree/main/omi/hardware/consumer/electrical/fpc-board/gerbers) | Gerber files |
| [`altium/`](https://github.com/BasedHardware/omi/tree/main/omi/hardware/consumer/electrical/fpc-board/altium) | Altium source |

<Warning>FPC is delicate — handle with care during assembly. The board-to-board connector has a limited insertion cycle count.</Warning>

How to Order PCBs

Upload the Gerber ZIP to any PCB manufacturer. Use the exact specs below per board:

Parameter Mainboard Charger Board FPC
Layers 4 (F.Cu, In1.Cu, In2.Cu, B.Cu) 2 2
Material FR4 FR4 Polyimide (flex)
Thickness 0.6mm 1.0mm 0.3mm
Board Size 21.0 x 21.0 mm 13.0 x 20.0 mm 29.3 x 12.5 mm
Surface Finish ENIG (immersion gold) ENIG ENIG
Min Trace/Space 0.076mm / 0.076mm (3 mil) 0.2mm / 0.127mm 0.254mm / 0.1mm
Solder Mask Both sides Both sides Both sides
Copper Weight 1 oz outer, 1/3 oz inner 1 oz 1 oz
The mainboard has blind vias (L1-L2, L3-L4) and buried vias (L2-L3) — confirm your fab supports these before ordering. Total 414 drill hits including 159 blind + 55 buried vias. Use **ENIG** surface finish for all boards. HASL causes bridging on the nRF5340 and nRF7002 fine-pitch pads (0.4mm). See the complete Bill of Materials with all 88 components

First Power-On Checklist

Check for solder bridges on QFN pads with a microscope or loupe. Verify all passives are placed correctly (check orientation of polarized capacitors). Connect bench supply (set to 3.7V, current limit 100mA). Measure VBAT (3.7V at battery input), VDD_nRF (1.0V for nRF5340 core), and VDDH (3.3V for nRF5340 I/O). 
<Warning>If current draw exceeds 50mA before firmware flash, disconnect immediately — likely a short.</Warning>
Connect SWD debugger (J-Link or nRF DK). Flash using nRF Connect SDK. See [firmware guide](/doc/developer/firmware/Compile_firmware). Open nRF Connect mobile app. The device should appear advertising as "Omi". If not, check 32MHz crystal and antenna matching network.

Troubleshooting

Check BQ25101 output (3.7-4.2V). Verify TPS628438 buck converter has correct input. Look for solder bridges on QFN pads with microscope. Measure resistance between VCC and GND — should be more than 1k ohm before power. Verify 32MHz crystal is soldered (not just tacked). Check 32.768kHz crystal for RTC. Measure nRF5340 VDDH (should be 3.3V) and VDD (1.0V). Check antenna trace and matching network. nRF7002 requires its own 40MHz crystal. Check BUCKA/BUCKB rails. Verify SPI connection between nRF5340 and nRF7002. Wi-Fi requires firmware support enabled. T5838 microphones are top-port — verify sound inlet faces the enclosure acoustic holes. Check PDM clock (1-3.25MHz) and data lines. Both mics must be in the correct PDM channel (L/R). Check pogo pin contact resistance (less than 0.5 ohm). Verify FPC connection. Measure charger board USB-C VBUS (5V). Check TPS25200 eFuse output. Verify magnet polarity alignment.