Arduino uno

Cave Uno (Rev 1.0)

English | Version Française 🇫🇷

Cave Uno is a next-generation open-source microcontroller development board engineered in Europe by Cave Rover. Conceived specifically for engineering, electronics, and technical students, as well as makers and university labs, Cave Uno is an upgraded, modern reinterpretation of the iconic Arduino Uno Rev3.

It retains 100% mechanical, electrical, and shield compatibility with the Uno R3 form factor while addressing all classic limitations through modern silicon: reversible USB-C with native plug-and-play driverless operation, a high-efficiency synchronous buck converter, zero-voltage-drop ideal diode power OR-ing, a high-current 3.3V rail, switchable logic voltage, the extended peripherals of the Microchip ATmega328PB, and high-precision LiDAR vector silkscreen art celebrating the Ardèche river canyon.

🖼️ 3D Assembled Board Overview (KiCad Raytracing)

🎓 Tailored for Technical & Engineering Education

Traditional 8-bit educational boards often suffer from fragile power regulators, obsolete USB connectors, driver configuration hurdles, and single-bus bottlenecks. Cave Uno addresses these issues directly for students and educators:

• 100% Shield & Form-Factor Compatibility: Fits existing Arduino Uno R3 shields, breadboard adapters, and lab enclosures without mechanical clashes.
• Driverless Out-of-the-Box Experience: No driver installers, unsigned driver warnings, or OS compatibility issues. Connect the USB-C cable and start coding immediately in the Arduino IDE.
• Laboratory-Grade Power Protection: Overvoltage-protected DC input, full TVS ESD suppression on USB data lines, and ideal diode reverse-current blocking prevent common lab wiring accidents.
• Real-World Bus Architecture: Teaches students modern multi-bus embedded design with Dual Hardware I2C (Wire / Wire1), Dual Hardware SPI, and Dual UART.
• Flexible Logic Interfacing: Eliminates messy resistor dividers and external level shifters when testing 3.3V sensors via the physical SW1 VDD rail selector.

⚡ Highlights & Key Features

• European Design & Heritage: Designed and routed in Europe (France / Ardèche), featuring LiDAR elevation contours of the Pont d'Arc canyon and UNESCO Chauvet Cave.
• Advanced ATmega328PB AVR Core @ 16 MHz:
  • Dual Hardware I2C (TWI0 & TWI1): Independent simultaneous buses.
  • Dual Hardware SPI (SPI0 & SPI1): High-speed parallel display and SD logging.
  • Dual USART (USART0 & USART1): Dedicated serial monitor + hardware sensor telemetry.
  • 9 PWM Channels: 3 extra output compare channels over standard 328P.
• Modern Driverless USB-C Connectivity: Powered by the WCH CH9101R USB-to-UART bridge with native OS CDC compliance across Windows 10/11, macOS, and Linux. No third-party drivers needed.
• High-Efficiency 1.5A Synchronous Buck Converter: Built with the AP63205 step-down DC-DC regulator, accepting 7V to 18V input with >90% efficiency.
• Zero-Drop Power OR-ing: Dual LM66100 ideal diode controllers manage seamless switching between USB and external power with virtually zero voltage drop.
• High-Current 600mA 3.3V Rail: Dedicated AP2112K-3.3 low-noise LDO powers modern power-hungry Wi-Fi (ESP8266/ESP32), radio (NRF24, LoRa), and sensor modules.
• Selectable VDD Header (SW1): A SPDT slide switch routes either +5V or +3.3V to the J9 expansion bus.
• Smart RGB NeoPixel LED: Integrated addressable WS2812B (2020) RGB LED connected to GPIO D23 (PE0) for user status and interactive tutorials.
• Dedicated I2C_0 Port (J7): Direct 4-pin connection (GND, 5V, SDA, SCL) for immediate sensor prototyping.
• Dedicated UART Port (J8): Direct 4-pin connection (RX0, TX0, GND, 5V) for serial modules and loggers.

📐 Pinout & Architecture

Comprehensive Pin-by-Pin Mapping Table

Every single pin across all headers on the board is detailed below:

🔬 Hardware Diagnostic & Lab Test Points (TP1 – TP15)

To facilitate oscilloscope probing, multimeter diagnostics, and hands-on electronics lab exercises, the Cave Uno integrates 15 surface-mount test pads (Ø 1.0 mm ENIG gold pads on F.Cu):

🛠️ Software Setup & Toolchain

The Cave Uno is 100% plug-and-play with the Arduino IDE, PlatformIO, VS Code, and AVR-GCC.

1. Arduino IDE Board Manager (MiniCore)

Because the ATmega328PB contains hardware peripherals beyond the legacy ATmega328P, install the MiniCore core package:

1. Open Arduino IDE, navigate to File → Preferences.
2. Add the following URL to Additional Boards Manager URLs:

   https://mcudude.github.io/MiniCore/package_MCUdude_MiniCore_index.json

3. Open Tools → Board → Boards Manager..., search for MiniCore by MCUdude, and click Install.
4. Configure your board settings under the Tools menu:
   • Board: ATmega328
   • Variant: 328PB
   • Clock: External 16 MHz
   • BOD: 2.7V (or 4.3V for strict 5V operation)
   • Compiler LTO: Enabled
   • Port: Select the detected CH9101 USB Serial Port.

2. Code Examples

Dual Independent I2C Buses

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  
  // Primary I2C bus (PC4/PC5 - Pins A4/A5 and Header J7)
  Wire.begin();
  
  // Secondary I2C bus (PE0/PE1 - Header J3)
  Wire1.begin();
  
  Serial.println(F("Cave Uno Dual I2C Initialized!"));
}

void loop() {
  // Query OLED display on primary bus
  Wire.beginTransmission(0x3C);
  // ...
  Wire.endTransmission();

  // Query sensor on secondary bus without address conflict
  Wire1.beginTransmission(0x68);
  // ...
  Wire1.endTransmission();

On-Board WS2812B Smart RGB LED (D23)

#include <Adafruit_NeoPixel.h>

#define RGB_PIN   23  // PE0 / D23
#define NUMPIXELS 1

Adafruit_NeoPixel statusLed(NUMPIXELS, RGB_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  statusLed.begin();
  statusLed.setBrightness(40);
}

void loop() {
  // Orange pulsing heartbeat (Cave Rover theme)
  statusLed.setPixelColor(0, statusLed.Color(249, 115, 22));
  statusLed.show();
  delay(800);
  
  statusLed.setPixelColor(0, statusLed.Color(0, 0, 0));
  statusLed.show();
  delay(200);
}

⚙️ Electrical Specifications

🏭 PCB Fabrication & Bare Board Preview

The PCB is authored in KiCad 10 with 2-layer FR4 stackup and 100% clean DRC (0 errors, 0 unrouted nets).

• Dimensions: 68.6 mm × 53.4 mm (Arduino Uno R3 standard envelope).
• Layer Stackup:
  • Top: 1 oz (35 µm) Copper (F.Cu)
  • Core: 1.5 mm FR4 Core
  • Bottom: 1 oz (35 µm) Copper (B.Cu)
• Recommended PCB Finish: ENIG (Electroless Nickel Immersion Gold) for coplanar QFN-32 and TSOT-23 pads.
• Soldermask: Matte Black / Charcoal (#1c1d21).
• Silkscreen: High-definition White (#f4f5f7).
• Clearance: Min 0.15 mm / 0.15 mm (6/6 mil).

🗺️ European Engineering & Heritage

The back of the PCB features precision vector topographic contour lines derived from LiDAR scans of the Pont d'Arc natural canyon in Ardèche, France, adjacent to the prehistoric Chauvet Cave (UNESCO World Heritage Site).

• Coordinates: $44^{\circ},23',15'',\text{N},\ 04^{\circ},24',59'',\text{E}$
• Silkscreen Artwork: Pure vector contours with solder-mask subtraction to preserve pristine gold pads.

📜 Key Silicon Bill of Materials

📄 License & Attribution

• Hardware Design: Licensed under the CERN-OHL-P v2 (CERN Open Hardware Licence - Permissive).
• Documentation & Artwork: Licensed under Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).
• Engineering & Design: Cave Rover (Europe, 2026).