6 I/O Multiplexing

Each pin is by default controlled by the PORT as a general purpose I/O and alternatively, it can be assigned to one of the peripheral functions.

The following table describes the peripheral signals multiplexed to the PORT I/O pins.

Table 6-1. PORT Function Multiplexing
NoPADEXTINTPCINTADC/ACPTC XPTC YOSCT/C USARTI2CSPI
1PD[3]INT1PCINT19 X3Y11 OC2B
2PD[4] PCINT20 X4Y12 T0 XCK0
3PE[0] PCINT24ACOX8Y16 ICP4 SDA1
4VCC
5GND
6PE[1] PCINT25 X9Y17 T4 SCL1
7PB[6] PCINT6 XTAL1/TOSC1
8PB[7] PCINT7 XTAL2/TOSC2
9PD[5] PCINT21 X5Y13 OC0B / T1
10PD[6] PCINT22AIN0X6Y14 OC0A
11PD[7] PCINT23AIN1X7Y15
12PB[0] PCINT0 X10Y18CLKOICP1
13PB[1] PCINT1 X11Y19 OC1A
14PB[2] PCINT2 X12Y20 OC1B SS0
15PB[3] PCINT3 X13Y21 OC2A TXD1 MOSI0
16PB[4] PCINT4 X14Y22 RXD1 MISO0
17PB[5] PCINT5 X15Y23 XCK1 SCK0
18AVCC
19PE[2] PCINT26ADC6 Y6 ICP3 SS1
20AREF
21GND
22PE[3] PCINT27ADC7 Y7 T3 MOSI1
23PC[0] PCINT8ADC0 Y0 MISO1
24PC[1] PCINT9ADC1 Y1 SCK1
25PC[2] PCINT10ADC2 Y2
26PC[3] PCINT11ADC3 Y3
27PC[4] PCINT12ADC4 Y4 SDA0
28PC[5] PCINT13ADC5 Y5 SCL0
29PC[6]/RESET PCINT14
30PD[0] PCINT16 X0Y8 OC3A RXD0
31PD[1] PCINT17 X1Y9 OC4ATXD0
32PD[2]INT0PCINT18 X2Y10 OC3B / OC4B