PCB Overview
Technical documentation for the RADR main PCB (OSSM Wireless v0.4)
This section covers the RADR main PCB design, including schematics, component specifications, and manufacturing files.
Board Overview
| Specification | Value |
|---|---|
| Board Name | OSSM Wireless |
| Version | v0.4 |
| Microcontroller | ESP32-S3 with PSRAM |
| Design Software | Altium Designer |
| Layer Count | 2 (estimated) |
The RADR PCB integrates all electronics required for a standalone wireless remote controller, including the microcontroller, display interface, power management, user inputs, and feedback systems.
Core Components
Microcontroller
| Parameter | Value |
|---|---|
| MCU | ESP32-S3 |
| Memory | Includes PSRAM |
| Wireless | WiFi + Bluetooth LE |
| Operating Voltage | 3.3V |
The ESP32-S3 provides:
- Dual-core Xtensa LX7 processor
- Integrated Bluetooth Low Energy for device communication
- Sufficient GPIO for all inputs, outputs, and peripherals
- Low-power sleep modes for battery conservation
Power Management
| Component | Function |
|---|---|
| USB-C Connector | 5V charging input |
| Charging IC | LiPo battery charging |
| MAX17048 | Fuel gauge (battery monitoring) |
| LDO/Regulator | 3.3V system power |
The power system supports:
- USB-C charging (5V input)
- Hardware charging LED indicator
- Precision battery percentage via I²C fuel gauge
- Deep sleep current < 100μA
Display Interface
| Parameter | Value |
|---|---|
| Display Type | TFT LCD |
| Resolution | 320 x 240 pixels |
| Color Depth | 16-bit (RGB565) |
| Interface | SPI |
| Backlight | PWM-controlled |
User Inputs
| Input | Type | GPIO |
|---|---|---|
| Left Encoder | Rotary + Push | GPIO 10, 11 |
| Right Encoder | Rotary + Push | GPIO 42, 41 |
| Left Shoulder | Momentary switch | GPIO 48 |
| Right Shoulder | Momentary switch | GPIO 1 |
| Under-Screen Left | Momentary switch | GPIO 38 |
| Under-Screen Center | Momentary switch | GPIO 39 |
| Under-Screen Right | Momentary switch | GPIO 40 |
GPIO assignments shown are for v0.4 boards with PSRAM. Earlier v1.x boards use different pins for the left encoder (GPIO 35, 36) and LEDs (GPIO 37).
Feedback Outputs
| Component | Type | GPIO |
|---|---|---|
| Status LEDs | WS2812B RGB (x3) | GPIO 12 |
| Buzzer | Piezoelectric | GPIO 2 |
| Vibration Motor | ERM motor | GPIO 47 |
Expansion
| Connector | Interface | Purpose |
|---|---|---|
| QWIIC | I²C | External sensors/peripherals |
| USB-C | USB 2.0 | Programming and charging |
Schematic Sections
The schematic is organized into functional blocks:
| Section | Description |
|---|---|
| Power | USB-C input, charging circuit, voltage regulation |
| MCU | ESP32-S3, crystal, reset, boot selection |
| Display | TFT LCD connector, backlight driver |
| Inputs | Rotary encoders, buttons, pull-up/pull-down resistors |
| Feedback | LED data line, buzzer driver, motor driver |
| Battery | MAX17048 fuel gauge, battery connector |
| Expansion | QWIIC connector, programming header |
PCB Layout Considerations
Component Placement
- MCU positioned centrally for balanced trace routing
- USB-C connector at board edge for accessibility
- Display connector oriented for ribbon cable routing to enclosure
- Battery connector positioned for internal battery placement
- QWIIC connector accessible for expansion modules
Antenna Considerations
The ESP32-S3 uses an integrated PCB antenna or external antenna (version dependent). The antenna area should be kept clear of:
- Ground planes directly beneath
- Metal enclosure proximity
- High-frequency switching signals
Do not place components or route traces in the antenna keepout zone. This significantly degrades wireless performance.
Design Files
All design files are available in the GitHub repository:
| File | Format | Description |
|---|---|---|
| PCB - OSSM Wireless v0.4.pcbdoc | Altium Designer | PCB layout with copper, silkscreen, drill files |
| Schematic - OSSM Wireless V0.4.schdoc | Altium Designer | Full schematic capture |
| RADR Schematic - OSSM Wireless V0.4.pdf | Printable schematic reference | |
| RADR BOM - OSSM Wireless - v0.4 - S3.xlsx | Excel | Bill of Materials with part numbers |
| RADR PCB render.png | PNG | 3D render of assembled board |
Download Design Files
Access Altium project files, Gerbers, and BOM on GitHub.
Manufacturing
PCB Fabrication
Recommended specifications for ordering:
| Parameter | Value |
|---|---|
| Layers | 2 |
| Thickness | 1.6mm |
| Surface Finish | HASL or ENIG |
| Copper Weight | 1oz |
| Solder Mask | Any color |
| Silkscreen | White |
Assembly Options
| Method | Recommended For |
|---|---|
| Hand Assembly | Prototypes, single units |
| PCBA Service | Production quantities |
Services like JLCPCB and PCBWay offer combined PCB fabrication and assembly. Upload the Gerbers and BOM for a turnkey solution.
Critical Components
These components require careful attention during assembly:
| Component | Notes |
|---|---|
| ESP32-S3 Module | Check orientation, ensure all pads are soldered |
| USB-C Connector | Requires precise alignment, check for shorts |
| MAX17048 | Small QFN package, needs proper reflow |
| WS2812B LEDs | Heat-sensitive, observe reflow profile |
Version History
| Version | Changes |
|---|---|
| v0.4 | Current release with ESP32-S3 |
Version v0.4 uses the ESP32-S3 variant. The "S3" suffix in the BOM filename indicates this variant.
Troubleshooting
- Check USB-C connection and cable
- Verify 3.3V regulator output
- Check for shorts on power rails
- Ensure battery is connected and charged
- Verify ribbon cable connection
- Check SPI signals with oscilloscope
- Confirm backlight PWM signal
- Test display power rails
- Check antenna area for shorts or bridges
- Verify ESP32-S3 is programmed correctly
- Ensure no metal near antenna zone
- Test with RF shield removed (if applicable)
- Verify USB-C CC resistors are present
- Check charging IC connections
- Measure battery voltage at connector
- Confirm charging LED circuit
- Check pull-up/pull-down resistors
- Verify GPIO assignments in firmware
- Test continuity from button to MCU
- Check for cold solder joints