7. AVR Pin Assignment Table Sorted by Pin

<table class="speccomp" cellspacing="0" align="center"> <tr> <th>Port A Pins</th> <th>Orangutan Function</th> <th>Notes/Alternate Functions</th> </tr> <tr><td>PA0</td><td>analog input and digital I/O</td><td>ADC input channel 0 (ADC0)</td></tr> <tr><td>PA1</td><td>analog input and digital I/O</td><td>ADC input channel 1 (ADC1)</td></tr> <tr><td>PA2</td><td>analog input and digital I/O</td><td>ADC input channel 2 (ADC2)</td></tr> <tr><td>PA3</td><td>analog input and digital I/O</td><td>ADC input channel 3 (ADC3)</td></tr> <tr><td>PA4</td><td>analog input and digital I/O</td><td>ADC input channel 4 (ADC4)</td></tr> <tr><td>PA5</td><td>analog input and digital I/O</td><td>ADC input channel 5 (ADC5)</td></tr> <tr><td>PA6</td><td>analog input and digital I/O</td><td>ADC input channel 6 (ADC6)</td></tr> <tr><td>PA7</td><td>analog input and digital I/O</td><td>ADC input channel 7 (ADC7)</td></tr> </table> <table class="speccomp" cellspacing="0" align="center"> <tr> <th>Port B Pins</th> <th>Orangutan Function</th> <th>Notes/Alternate Functions</th> </tr> <tr><td>PB1</td><td><strong>LCD control line R/W</strong></td><td>Divided system clock output (CLKO)<br/>Timer/Counter 1 External Counter Input (T1)</td></tr> <tr><td>PB2</td><td><strong>LCD control line E</strong></td><td>External interrupt 2 (INT2)<br/>Analog Comparator Positive Input (AIN0)</td></tr> <tr><td>PB3</td><td>digital I/O</td><td>Timer0 PWM output A (OC0A)<br/>Analog Comparator Negative Input (AIN1)</td></tr> <tr><td>PB4</td><td>digital output*</td><td>Timer0 PWM output B (OC0B)<br/>SPI Slave Select Input (<span style="text-decoration:overline;">SS</span>)</td></tr> <tr><td>PB5</td><td><strong>auxiliary processor control line</strong></td><td>SPI Master Output/Slave Input (MOSI)<br/>ISP programming line</td></tr> <tr><td>PB6</td><td><strong>auxiliary processor control line</strong></td><td>SPI Master Input/Slave Output (MISO)<br/>ISP programming line</td></tr> <tr><td>PB7</td><td><strong>auxiliary processor control line</strong></td><td>SPI Clock (SCK)<br/>ISP programming line</td></tr> </table> <table class="speccomp" cellspacing="0" align="center"> <tr> <th>Port C Pins</th> <th>Orangutan Function</th> <th>Notes/Alternate Functions</th> </tr> <td>PC0</td><td>digital I/O</td><td>I2C/TWI clock line (SCL)</td></tr> <tr><td>PC1</td><td>digital I/O</td><td>I2C/TWI input/output data line (SDA)</td></tr> <tr><td>PC2</td><td><strong>LCD data line DB4</strong></td><td><strong>user pushbutton</strong> (pressing pulls low)</td></tr> <tr><td>PC3</td><td><strong>LCD data line DB5</strong></td><td><strong>user pushbutton</strong> (pressing pulls low)</td></tr> <tr><td>PC4</td><td><strong>LCD data line DB6</strong></td><td><strong>green user LED</strong> (high turns LED on)</td></tr> <tr><td>PC5</td><td><strong>LCD data line DB7</strong></td><td><strong>user pushbutton</strong> (pressing pulls low)</td></tr> <tr><td>PC6</td><td><strong>M2 direction control line</strong></td><td></td></tr> <tr><td>PC7</td><td><strong>M1 direction control line</strong></td><td></td></tr> </table> <table class="speccomp" cellspacing="0" align="center"> <tr> <th>Port D Pins</th> <th>Orangutan Function</th> <th>Notes/Alternate Functions</th> </tr> <td>PD0</td><td>digital I/O</td><td>USART0 input pin (RXD0)</td></tr> <tr><td>PD1</td><td>digital I/O</td><td><strong>red user LED</strong><br/>(low turns LED on; connection<br/>can be cut and replaced with jumper)<br/>USART0 output pin (TXD0)</td></tr> <tr><td>PD2</td><td>digital I/O</td><td>USART1 input pin (RXD1)<br/>External interrupt 0 (INT0)</td></tr> <tr><td>PD3</td><td>digital I/O</td><td>USART1 output pin (TXD1)<br/>External interrupt 1 (INT1)</td></tr> <tr><td>PD4</td><td><strong>buzzer</strong></td><td>Timer1 PWM output B (OC1B)</td></tr> <tr><td>PD5</td><td>digital I/O</td><td><strong>servo pulse output (SPWM)</strong><br/>Timer1 PWM output A (OC1A)</td></tr> <tr><td>PD6</td><td><strong>M2 speed control line</strong></td><td>Timer2 PWM output B (OC2B)</td></tr> <tr><td>PD7</td><td><strong>M1 speed control line</strong></td><td>Timer2 PWM output A (OC2A)</td></tr> </table> <table class="speccomp" cellspacing="0" align="center"> <tr> <th>Misc. Pins</th> <th>Orangutan Function</th> <th>Notes/Alternate Functions</th> </tr> <tr><td>AREF</td><td>ADC reference pin</td><td></td></tr> <tr><td>AVCC</td><td>supply voltage for Port A and ADC</td><td>not accessible to the user</td></tr> <tr><td>RESET</td><td>Reset input</td><td><strong>reset button</strong> (pressing resets MCU)</td></tr> <tr><td>XTAL1</td><td>20 MHz resonator input</td><td>not accessible to the user</td></tr> <tr><td>XTAL2</td><td>20 MHz resonator input</td><td>not accessible to the user</td></tr> </table> <p><b>*</b>: Using PB4/<span style="text-decoration:overline;">SS</span> as an input will interfere with communication to the auxiliary processor, so we recommend using it as a digital output. See <a href="/docs/0J20/3.j">Section 3.j</a> of the Pololu USB AVR C/C++ User&#8217;s Guide for more information.</p>