I/O Port Multiplexing

Each pin of ATmega328PB is default controlled as a general purpose I/O and can be alternatively assigned to one of the peripheral functions. The table below describes the peripheral signals multiplexed to the PORT I/O pins.

Table 1. Port Function Multiplexing
No PAD EXINT PCINT ADC/AC PTC X PTC Y OSC T/C #0 T/C #1 USART I2C SPI
1 PD[3] INT1 PCINT19   X3 Y11   OC2A        
2 PD[4]   PCINT20   X4 Y12   T0   XCK0    
3 PE[0]   PCINT24 ACO X8 Y16     ICP4   SDA1  
4 VCC                      
5 GND                      
6 PE[1]   PCINT25   X9 Y17     TC4   SCL1  
7 PB[6]   PCINT6       XTAL1/TOSC1          
8 PB[7]   PCINT7       XTAL2/TOSC2          
9 PD[5]   PCINT21   X5 Y13   OC0B T1      
10 PD[6]   PCINT22 AIN0 X6 Y14   OC0A        
11 PD[7]   PCINT23 AIN1 X7 Y15            
12 PB[0]   PCINT0   X10 Y18 CLKO ICP1        
13 PB[1]   PCINT1   X11 Y19   OC1A        
14 PB[2]   PCINT2   X12 Y20   OC1B       SS0
15 PB[3]   PCINT3   X13 Y21   OC2A   TXD1   MOSI0
16 PB[4]   PCINT4   X14 Y22       RXD1   MISO0
17 PB[5]   PCINT5   X15 Y23       XCK1   SCK0
18 AVCC                      
19 PE[2]   PCINT26 ADC6   Y6   ICP3       SS1
20 AREF                      
21 GND                      
22 PE[3]   PCINT27 ADC7   Y7   T3       MOSI1
23 PC[0]   PCINT8 ADC0   Y0           MISO1
24 PC[1]   PCINT9 ADC1   Y1           SCK1
25 PC[2]   PCINT10 ADC2   Y2            
26 PC[3]   PCINT11 ADC3   Y3            
27 PC[4]   PCINT12 ADC4   Y4         SDA0  
28 PC[5]   PCINT13 ADC5   Y5         SCL0  
29 PC[6]/Reset   PCINT14                  
30 PD[0]   PCINT16   X0 Y8   OC3A   RXD0    
31 PD[1]   PCINT17   X1 Y9     OC4A TXD0    
32 PD[2]   PCINT18   X2 Y10   OC3B OC4B