PCB Overview

The Moto32 PCB is a compact, multi-layer board designed specifically for motorcycle applications, featuring automotive-grade protection and robust construction.

PCB Specifications

Physical Characteristics

Surface Finish Options

Color Options

While purely aesthetic, PCB color can help with assembly and debugging:

• Black: Professional appearance, hides components
• Blue: High contrast for component identification
• Green: Standard color, good visibility
• Red: Eye-catching, shows traces clearly

PCB Layout

Top Side Components

Major Components (Top):

• U1: ESP32-S3-WROOM-1-N8R2 module (main MCU)
• U2: CH340C USB-to-UART converter
• U3: AP63203WU-7 buck converter
• Q5-Q12: 8x DMP4015SK3Q-13 MOSFET switches
• USB-C1: TYPE-C-31-M-12 connector
• Various: Capacitors, resistors, protection diodes

Bottom Side

The bottom layer typically contains:

• Ground plane
• Additional routing
• Thermal relief pads
• Component markings

Layer Stackup

Typical Multi-Layer Structure:

┌─────────────────────┐
│  Top Copper (L1)    │ ← Component side, signal traces
├─────────────────────┤
│  Dielectric         │
├─────────────────────┤
│  Inner Layer (L2)   │ ← Ground plane
├─────────────────────┤
│  Dielectric         │
├─────────────────────┤
│  Inner Layer (L3)   │ ← Power plane (12V, 3.3V)
├─────────────────────┤
│  Dielectric         │
├─────────────────────┤
│  Bottom Copper (L4) │ ← Additional routing, ground
└─────────────────────┘

Design Sections

Power Supply Section

12V Input → 3.3V Regulated Output

Components:

• U3 (AP63203WU-7): Switching buck converter
  • Input: 12V nominal (9-16V tolerance)
  • Output: 3.3V @ 2A max
  • Efficiency: >90% typical
• D1 (SS34): Input protection Schottky diode
• C2, C10, C11: Output filtering capacitors
• L1: Output inductor (if present)

Features:

• Wide input voltage range (automotive transients)
• Thermal shutdown protection
• Current limiting
• Stable 3.3V for ESP32 and logic

USB Interface Section

USB-C to Serial Converter

Components:

• USB-C1: USB Type-C connector
• U2 (CH340C): USB-to-UART bridge
• X1: 12MHz crystal for CH340C
• D4, D5: TVS diodes for USB protection
• R18-R21: USB data line resistors

Features:

• USB-C connector (modern standard)
• Automatic driver installation (CH340)
• ESD protection on USB lines
• 115200 baud default communication

ESP32-S3 Section

Main Microcontroller

Components:

• U1 (ESP32-S3-WROOM-1): Main MCU module
• C1, C3-C9: Decoupling capacitors
• R1: EN pull-up resistor
• R2: Boot mode resistor
• Programming header: UART0 connections

Features:

• Dual-core Xtensa LX7 @ 240MHz
• 8MB Flash, 2MB PSRAM
• Wi-Fi 802.11 b/g/n
• Bluetooth 5.0 LE
• Rich GPIO and peripheral set

MOSFET Output Section

8x High-Side Switches

Components per channel:

• Q5-Q12 (DMP4015SK3Q-13): P-channel MOSFET
  • RDS(on): Low resistance
  • Max current: Per datasheet
  • Logic-level gate drive
• R6-R17: Gate resistors (10kΩ)
• Pull-up resistors: Keep outputs off by default

Features:

• Logic LOW activates output (pulls gate to GND)
• Logic HIGH or floating keeps output OFF
• Suitable for automotive loads (lights, horn, etc.)
• Short-circuit tolerant (with proper fusing)

Output Channel Mapping:

Protection Circuits

Multi-Layer Protection:

• TVS Diodes (D4, D5): Transient voltage suppression
  • Clamp voltage spikes from ignition, starter motor
  • Protect sensitive electronics
• Schottky Diode (D1): Reverse polarity protection
• Fuse: External 10A inline fuse recommended
• Decoupling Capacitors: Filter noise on power rails
• Ground Planes: Low impedance return path

Design Considerations

Automotive Environment

The PCB is designed for harsh motorcycle conditions:

Vibration Resistance:

• Multiple ground plane stitching vias
• Large solder pads for through-hole components
• Mechanical support for heavy components (ESP32 module)

Temperature Range:

• Components rated for automotive temps (-40°C to +85°C)
• Adequate spacing for thermal expansion
• Heat dissipation considerations for MOSFETs

Moisture Protection:

• Conformal coating recommended for exposed installations
• No exposed copper on edges
• Sealed connectors preferred

Electrical Noise:

• Ground planes for EMI shielding
• Decoupling capacitors near every IC
• Separate analog and digital grounds (if applicable)
• Twisted pair or shielded wires for sensors

PCB Images

3D Render

Features visible:

• Component placement and orientation
• Connector positions
• Mounting hole locations
• Overall board dimensions

Schematic Preview

See the Schematics page for detailed circuit diagrams.

Manufacturing Notes

For PCB Manufacturers

When ordering, specify:

PCB Specifications:
  Material: FR-4
  Layers: Multi-layer (auto-detect from Gerber)
  Thickness: 1.6mm
  Surface Finish: ENIG preferred, HASL acceptable
  Copper Weight: 1 oz (35µm)
  Solder Mask: Your choice (blue/black recommended)
  Silkscreen: White (on dark colors) or black (on light colors)
  Min Trace/Space: As designed in Gerber
  Min Hole Size: As designed in Gerber
  Edge Connector: No
  Castellated Holes: No

For Assembly Services

Provide these files:

• Gerber package (Gerber_Canarin_MUX_PCB.zip)
• BOM (BOM_Canarin_MUX.csv)
• Pick & Place (PickAndPlace_PCB_Canarin_MUX.csv)

Assembly Notes:

• All components are SMD (surface mount)
• Smallest packages: 0402 (resistors/capacitors)
• Some components may require manual placement
• Reflow profile: Lead-free SAC305

Testing Points

Recommended Test Points:

Design Files

All design files are available in the repository:

Modifications & Customization

The open-source nature allows you to modify the PCB:

Common Modifications:

• Add more MOSFET channels for additional outputs
• Include current sensing resistors for monitoring
• Add CAN bus transceiver for vehicle communication
• Include IMU for lean angle sensing (auto-cancel)
• Add relay drivers for higher current loads
• Include voltage dividers for analog input reading

Before Modifying:

1. Review the schematic thoroughly
2. Understand the circuit operation
3. Check component datasheets
4. Verify electrical ratings
5. Run design rule checks (DRC)
6. Prototype and test before production

Next Steps