![]() ![]() The change interrupt can be generated by any pins of a port, and such pins are labeled as PCINTxx on the pinout diagram.Due to a slight difference between ATmega328 and ATmega328P, many of us get confused about which IC should be used. But all GPIO ports also have common change interrupt capability. These interrupts can detect FALLING, RISING, LOW or CHANGE triggers. There are only two external interrupt pins available on ATmega328P called INT0 and INT1. You can learn more about Arduino Uno PWM from – Secrets of Arduino PWM. You can use the analogWrite() function to output the PWM waveform. PWM output is supported by 6 pins in the Arduino environment, labeled as OCxx on the pinout diagram. The hardware timer blocks of ATmega328P can be used to generate PWM (Pulse Width Modulation) of varying duty cycles and frequencies. There are two additional inputs AIN0 and AIN1 used for analog comparator inputs. Pin #ĪTmega328P has a single 10-bit ADC with 6 multiplexed channels. I2C is also called Wire in the Arduino environment. The I2C pins also share ADC input functions. There is only one I2C (Inter-Integrated Circuit) interface available in ATmega328P. There are two SPI (Serial Peripheral Interface) ports available in ATmega328P but one is shared with the UART. Hardware flow control pins (CTS, RTS) are not available in the Arduino framework. If you need extra UART ports, you can consider using the SoftwareSerial library. UARTĪTmega328P has only 1 UART and the TXD and RXD pins are connected to the USB-Serial chip on an Arduino Uno. You can access the LED pin as LED_BUILTIN in the Arduino IDE. Pin #Īrduino Uno has an onboard LED for debugging. All GPIO pins support internal pull-ups in the range of 20-50K. Some alternate function pins are excluded. ![]() If you are new to Arduino, we have a complete tutorial covering the basics of Arduino development framework using the popular Arduino Uno board.Įven though ATmega328P has 23 GPIOs, only 20 are available in the Arduino framework. Arduino Pinsīelow are Arduino pin assignments used for the official Arduino Uno board with an ATmega328P. RESET also has GPIO function but it can only be used when the external reset function is disabled. A LOW pulse of 2.5 μs or longer can reset the MCU (without the capacitor). This pin is usually pulled up with a 10K resistor and a 0.1uF capacitor connected to GND. RESET is an active-low external reset input for ATmega328P. The AREF pin is used to decouple the ADC reference voltage for better noise performance. The ATmega328P has two options for the ADC reference voltage an internal reference of 1.1V (nominal) and AVCC supply. You could connect a low-noise supply to this pin, but in that case, the supply voltage must not differ from the VCC by more than ☐.3V. This pin should be connected to VCC externally along with a filter capacitor, even if the ADC is not used. ![]() AVCCĪVCC is the supply pin for the internal ADC of ATmega328P. See “Alternate Functions of Port B” in the datasheet for more info. Both pins have IO functions, but those functions can be not used while the pins are used for clock input. If you have an external clock source, it can be connected to XTAL1 while leaving XTAL2 floating. The fuses also need to be configured to select an external oscillator. A crystal oscillator can be connected to these pins along with capacitors. XTAL1 and XTAL2 are the pins for providing external clock signals to the microcontroller. Changing the voltage will also change the maximum clock frequency the microcontroller can run reliably. All GND pins should be connected together. Click the link to open an interactive preview, or download it directly.ĪTmega328P-28-DIP-Pinout-Diagram-Rev-0.5-CIRCUITSTATE-Electronics-1 Download Pin Reference Power & Control VCC & GND PDF preview may not load on mobile devices. PNG Click for higher resolutionĮven though only Arduino digital pins are shown, all other peripheral pins have the same functions in the Arduino environment. If you found any errors here, please let us know in the comments. Please also double-check the pin assignments with that from the official documentation. While we try our best to be accurate and up-to-date here, we can not guarantee correctness. Pinouts are based on the latest documentation from the manufacturer. ![]() 6 (Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby) ![]()
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