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This section covers the RADR main PCB design, including schematics, component specifications, and manufacturing files.

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Board Overview

SpecificationValue
Board NameOSSM Wireless
Versionv0.4
MicrocontrollerESP32-S3 with PSRAM
Design SoftwareAltium Designer
Layer Count2 (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.
RADR PCB Render

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Core Components

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Microcontroller

ParameterValue
MCUESP32-S3
MemoryIncludes PSRAM
WirelessWiFi + Bluetooth LE
Operating Voltage3.3V
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

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Power Management

ComponentFunction
USB-C Connector5V charging input
Charging ICLiPo battery charging
MAX17048Fuel gauge (battery monitoring)
LDO/Regulator3.3V 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

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Display Interface

ParameterValue
Display TypeTFT LCD
Resolution320 x 240 pixels
Color Depth16-bit (RGB565)
InterfaceSPI
BacklightPWM-controlled

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User Inputs

InputTypeGPIO
Left EncoderRotary + PushGPIO 10, 11
Right EncoderRotary + PushGPIO 42, 41
Left ShoulderMomentary switchGPIO 48
Right ShoulderMomentary switchGPIO 1
Under-Screen LeftMomentary switchGPIO 38
Under-Screen CenterMomentary switchGPIO 39
Under-Screen RightMomentary switchGPIO 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).

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Feedback Outputs

ComponentTypeGPIO
Status LEDsWS2812B RGB (x3)GPIO 12
BuzzerPiezoelectricGPIO 2
Vibration MotorERM motorGPIO 47

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Expansion

ConnectorInterfacePurpose
QWIICI²CExternal sensors/peripherals
USB-CUSB 2.0Programming and charging

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Schematic Sections

The schematic is organized into functional blocks:
SectionDescription
PowerUSB-C input, charging circuit, voltage regulation
MCUESP32-S3, crystal, reset, boot selection
DisplayTFT LCD connector, backlight driver
InputsRotary encoders, buttons, pull-up/pull-down resistors
FeedbackLED data line, buzzer driver, motor driver
BatteryMAX17048 fuel gauge, battery connector
ExpansionQWIIC connector, programming header

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PCB Layout Considerations

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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

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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.

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Design Files

All design files are available in the GitHub repository:
FileFormatDescription
PCB - OSSM Wireless v0.4.pcbdocAltium DesignerPCB layout with copper, silkscreen, drill files
Schematic - OSSM Wireless V0.4.schdocAltium DesignerFull schematic capture
RADR Schematic - OSSM Wireless V0.4.pdfPDFPrintable schematic reference
RADR BOM - OSSM Wireless - v0.4 - S3.xlsxExcelBill of Materials with part numbers
RADR PCB render.pngPNG3D render of assembled board

Download Design Files

Access Altium project files, Gerbers, and BOM on GitHub.

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Manufacturing

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PCB Fabrication

Recommended specifications for ordering:
ParameterValue
Layers2
Thickness1.6mm
Surface FinishHASL or ENIG
Copper Weight1oz
Solder MaskAny color
SilkscreenWhite

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Assembly Options

MethodRecommended For
Hand AssemblyPrototypes, single units
PCBA ServiceProduction quantities
Services like JLCPCB and PCBWay offer combined PCB fabrication and assembly. Upload the Gerbers and BOM for a turnkey solution.

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Critical Components

These components require careful attention during assembly:
ComponentNotes
ESP32-S3 ModuleCheck orientation, ensure all pads are soldered
USB-C ConnectorRequires precise alignment, check for shorts
MAX17048Small QFN package, needs proper reflow
WS2812B LEDsHeat-sensitive, observe reflow profile

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Version History

VersionChanges
v0.4Current release with ESP32-S3
Version v0.4 uses the ESP32-S3 variant. The “S3” suffix in the BOM filename indicates this variant.

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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

Hardware Overview

Complete hardware specifications and GPIO mappings.

Battery & Power

Detailed power management and charging documentation.

Printed Parts

3D printed enclosure that houses the PCB.

Feedback Systems

LED, buzzer, and vibration motor details.