Arduino Uno Symbol
Definition: The Arduino Uno symbol represents the Arduino Uno R3 microcontroller development board — a popular open-source hardware platform based on the ATmega328P microcontroller — shown in circuit schematics as a rectangular block with labelled I/O pins including digital (D0–D13), USB power input, and other interface connections.
Also known as: Arduino Uno, Arduino board, Arduino MCU block, ATmega Arduino, Arduino schematic block.
What the Arduino Uno symbol means
The Arduino Uno symbol in a schematic represents the entire Uno development board as a single functional block, abstracting away the onboard voltage regulators, crystal oscillator, USB-to-serial converter, and decoupling capacitors. The symbol exposes the externally accessible pins — digital I/O lines and USB power — allowing a designer to show how external components (sensors, displays, motors) connect to the Arduino without drawing every internal circuit detail.
In wiring diagrams and hobbyist electronics schematics, the Arduino Uno symbol is the central hub that other peripheral symbols connect to. Each pin on the symbol corresponds to a physical header pin on the physical board. The schematic symbol is most useful in system-level block diagrams and wiring diagrams rather than in detailed PCB netlists where the full ATmega328P schematic would be used instead.
How to identify the Arduino Uno symbol
The Arduino Uno symbol is drawn as a rectangular block with the label 'Arduino Uno' or 'ARDUINO'. Digital I/O pin connections (D0, D2, D4, D6, D8, D10, D12) emerge from the top edge, and a USB connection pin emerges from the bottom edge. Some schematic tools show additional analog pins (A0–A5) and power pins (5V, 3.3V, GND) on the side edges. The distinctive board outline is not shown in the schematic symbol — only the functional pin labels and the block rectangle.
Function and usage boundary
The Arduino Uno functions as a programmable microcontroller platform with 14 digital I/O pins (6 of which support PWM output), 6 analog input pins (10-bit ADC), UART, SPI, and I2C interfaces, and a 16 MHz clock. In a circuit, it reads sensors via its ADC and digital inputs, executes user-written firmware (Arduino sketches compiled from C++), and drives outputs such as LEDs, motors, and displays. The onboard USB interface (via ATmega16U2) allows programming and serial communication with a PC.
Standards: IEC vs ANSI
| IEC 60617 | The Arduino Uno is represented in schematics as a rectangular logic block per IEC 60617-12 conventions for integrated circuits and modules. IEC does not define a specific symbol for the Arduino Uno board itself; the block-level representation follows general IC symbol conventions. |
|---|---|
| ANSI/IEEE 315 | Under ANSI/IEEE 315-1975 conventions, the Arduino Uno is treated as a module or subsystem and drawn as a rectangular box with labelled pins. No specific ANSI symbol code exists for the Arduino Uno board specifically. |
| Key difference | No IEC vs. ANSI glyph difference applies to the Arduino Uno block symbol, as both standards use rectangular blocks for IC/module representations. The pin labelling (D0, D2, USB, etc.) is consistent across schematic tools. |
The displayed SVG is the live editor implementation, not a licensed reproduction or certification of an IEC or IEEE database glyph. Verify the exact official entry and project edition before issuing work.
Logical terminals
| Logical ID | Editor terminal name |
|---|---|
| d0 | D0 |
| d2 | D2 |
| d4 | D4 |
| d6 | D6 |
| d8 | D8 |
| d10 | D10 |
| d12 | D12 |
| usb | USB |
Where the Arduino Uno symbol is used
- Prototype wiring diagrams connecting sensors (DHT11, ultrasonic, IR) to Arduino I/O pins
- Home automation circuit schematics where Arduino controls relays, LEDs, and servos
- Educational electronics projects showing how to interface LCDs, motors, and keypads
- Robotics system diagrams where Arduino acts as the main controller driving motor drivers and encoders
- IoT project schematics pairing Arduino with Wi-Fi shields (ESP8266) or Ethernet shields
- Data-logging projects connecting analog sensors to Arduino ADC pins and SD card modules
- Beginner electronics workshops demonstrating microcontroller I/O in block-level diagrams
Key facts
- The Arduino Uno symbol represents the Arduino Uno R3 development board (ATmega328P MCU) as a single rectangular block with exposed I/O pins in schematic and wiring diagrams.
- The schematic symbol exposes digital pins D0, D2, D4, D6, D8, D10, D12, and a USB power/communication pin; the physical board has 14 digital I/O pins and 6 analog inputs, and some are not shown in the simplified block.
- The Arduino Uno uses a 16 MHz crystal oscillator and a 5 V operating voltage supplied via USB (5 V) or a barrel jack (7–12 V, regulated onboard by an LM7805-compatible regulator).
- Digital pins D0 (RX) and D1 (TX) are shared with the USB-to-serial interface; using them for general I/O while the USB is connected can cause serial communication conflicts.
- Pins D3, D5, D6, D9, D10, and D11 support 8-bit PWM output (analogWrite() in Arduino IDE), allowing dimming, motor speed control, and audio generation.
- The Arduino Uno has no built-in Ethernet, Wi-Fi, or Bluetooth; these are added via shield boards stacked on the headers, each shown as a separate symbol in the schematic.
- In professional PCB netlists the ATmega328P is used directly (see the atmega328 symbol) rather than the Arduino Uno block, which is reserved for system-level and wiring diagram use.
- The USB pin on the schematic symbol represents the USB-B connector which provides 5 V power and serial programming capability via the ATmega16U2 USB bridge.
Diagrams that use this symbol
- throttle position sensor diagram
- diagram of thermocouple
- sensor diagram
- encoder circuit diagram
- 3 wire crank sensor wiring diagram
- 2 wire temp sensor wiring diagram
- 4 wire o2 sensor wiring diagram
- 4 wire oxygen sensor wiring diagram
Frequently asked questions
What does the Arduino Uno symbol look like in a circuit diagram?
The Arduino Uno symbol is a rectangle labelled 'Arduino Uno' or 'ARDUINO'. Digital I/O pins (D0, D2, D4, D6, D8, D10, D12) exit from the top edge, and a USB pin exits from the bottom. Some tool implementations also show analog pins (A0–A5) and power pins (5V, GND) on the side edges.
What does the Arduino symbol mean in a schematic?
The Arduino symbol represents the entire Arduino Uno development board as a single functional block. It shows which board pins are used in the circuit and how they connect to external components — sensors, displays, motors — without showing the internal ATmega328P circuitry in detail.
What is the difference between the Arduino Uno symbol and the ATmega328 symbol?
The Arduino Uno symbol represents the whole development board as a black-box block, exposing only the external header pins. The ATmega328 symbol (see the atmega328 entry) represents just the microcontroller IC with all its port pins (PC6/RST, PD0/RX, PB0, etc.), suitable for detailed PCB schematic design without the Arduino bootloader or USB interface circuitry.
How many I/O pins does the Arduino Uno have?
The Arduino Uno R3 has 14 digital I/O pins (D0–D13), 6 of which support 8-bit PWM output (D3, D5, D6, D9, D10, D11), and 6 analog input pins (A0–A5, each with a 10-bit ADC). It also has dedicated SPI (D10–D13), I2C (A4/A5), and UART (D0/D1) pins.
What standard defines the Arduino Uno schematic symbol?
No formal IEC or ANSI standard defines the Arduino Uno schematic symbol specifically. The rectangular block representation follows general IEC 60617-12 and ANSI/IEEE 315-1975 conventions for IC and module blocks. The pin labels (D0, D2, USB) follow the official Arduino Uno board pinout documentation.
What is the operating voltage of the Arduino Uno?
The Arduino Uno operates at 5 V. It can be powered via USB (5 V) or via the barrel jack connector (7–12 V recommended, 6–20 V absolute range), which is regulated to 5 V by the onboard voltage regulator. The I/O pins are 5 V logic, which is not directly compatible with 3.3 V devices without a level shifter.
What are the PWM pins on the Arduino Uno?
The Arduino Uno has six PWM-capable digital pins: D3, D5, D6, D9, D10, and D11. These produce an 8-bit PWM signal (0–255 duty cycle) at approximately 490 Hz (D3, D9, D10, D11) or 980 Hz (D5, D6) using the Arduino analogWrite() function, suitable for motor speed control, LED dimming, and simple DAC applications.
Related symbols
Physical components that use this symbol
A schematic symbol defines electrical intent; the physical profile adds package or panel dimensions and mounting data.
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