Summary |
http://arduino.cc/en/Main/ArduinoBoardUno |
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Microcontroller |
ATmega328 |
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Operating Voltage |
5V |
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Input Voltage (recommended) |
7-12V |
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Input Voltage (limits) |
6-20V |
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Digital I/O Pins |
14 (of which 6 provide PWM output) |
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Analog Input Pins |
6 |
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DC Current per I/O Pin |
40 mA |
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DC Current for 3.3V Pin |
50 mA |
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Flash Memory |
32 KB (ATmega328) of which 0.5 KB used by bootloader |
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SRAM |
2 KB (ATmega328) |
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EEPROM |
1 KB (ATmega328) |
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Clock Speed |
16 MHz |
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Input and Output |
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Each of the 14 digital pins on the Uno can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor (disconnected by default) of 20-50 kOhms. In addition, some pins have specialized functions: |
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Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip. |
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External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. See the attachInterrupt() function for details. |
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PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analogWrite() function. |
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SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication using the SPI library. |
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LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off. |
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TWI: A4 or SDA pin and A5 or SCL pin. Support TWI communication using the Wire library. |
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ATmega328 Pin Mapping |
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I/O |
Pin 1 |
Reset |
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Pin 2 |
PD0 (Rs232 - Rx) |
0 |
Pin 3 |
PD1 (Rs232 - Tx) |
1 |
Pin 4 |
PD2 (Int / Rs232 - Rx.1) |
2 |
Pin 5 |
PD3 (Int / Rs232 - Tx.1 / PWM_3) |
3 |
Pin 6 |
PD4 |
4 |
Pin 7 |
VCC (5v) |
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Pin 8 |
GND |
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Pin 9 |
TOSC1 |
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Pin 10 |
TOSC2 |
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Pin 11 |
PD5 (PWM_5) |
5 |
Pin 12 |
PD6 (PWM_6) |
6 |
Pin 13 |
PD7 |
7 |
Pin 14 |
PB0 |
8 |
Pin 15 |
PB1 (PWM_9) |
9 |
Pin 16 |
PB2 (PWM_10) |
10 |
Pin 17 |
PB3 (PWM_11) |
11 |
Pin 18 |
PB4 |
12 |
Pin 19 |
PB5 (LED) |
13 |
Pin 20 |
AVCC |
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Pin 21 |
AREF |
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Pin 22 |
GND |
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Pin 23 |
PC0 (ADC0) |
ADC0 |
Pin 24 |
PC1 (ADC1) |
ADC1 |
Pin 25 |
PC2 (ADC2) |
ADC2 |
Pin 26 |
PC3 (ADC3) |
ADC3 |
Pin 27 |
PC4 (ADC4) |
ADC4 |
Pin 28 |
PC5 (ADC5) |
ADC5 |