Custom Arduino Uno

This is a custom Arduino Uno compatible development board. It is based on the ATmega328P-PU microcontroller and uses an ATmega16U2 chip for USB-to-Serial communication, just like the official Arduino Uno R3.

The board operates at 5 volts and includes a 3.3V low dropout (LDO) regulator for devices that need 3.3V. Power can be supplied through the USB port or from an external source using jumper settings. A micro-USB connector is used for programming and power input.

It provides 14 digital input/output pins, of which 6 can be used as PWM outputs, and 6 analog input pins labeled A0 to A5. It includes dedicated I2C (A4 and A5) and SPI pins. The pin headers follow the standard Arduino Uno layout so that shields and accessories are compatible.

There are separate ICSP headers for both the ATmega328P and ATmega16U2 microcontrollers for in-system programming. The board includes automatic reset circuitry to allow uploading sketches directly from the Arduino IDE without pressing any button.

The board has a 16 MHz crystal oscillator for both the ATmega328P and the ATmega16U2. Each chip also has supporting components like decoupling capacitors, pull-up resistors, and USB protection components like ferrite beads and 22-ohm resistors on the data lines.

Additional features include:

• Power LED to indicate the board is powered

• User LED connected to a digital pin

• USB TX and RX LEDs to show data transfer

• Reset button for ATmega328P

• A second user button

• Jumpers for power selection and reconfiguration

This custom board is fully compatible with the Arduino Uno bootloader and works with the Arduino IDE for development and uploading sketches.