17.3.4 Alternate Functions of Port E

The Port E pins with alternate functions are shown in this table:

The alternate pin configuration is as follows:

• ADC7/T3/MOSI1/PCINT27– Port E, Bit 3
  • PE3 can also be used as ADC input Channel 7.
  • T3: Timer/Counter3 counter source.
  • MOSI1: SPI1 Master Data output, Slave Data input for SPI1 channel. When the SPI1 is enabled as a Slave, this pin is configured as an input regardless of the setting of DDE3. When the SPI1 is enabled as a Master, the data direction of this pin is controlled by DDE3. When the pin is forced by the SPI1 to be an input, the pull-up can still be controlled by the PORTE3 bit.
  • PCINT27: Pin Change Interrupt source 27. The PE3 pin can serve as an external interrupt source.

• ADC6/ICP3/SS1/PCINT26 – Port E, Bit 2
  • PE2 can also be used as ADC input Channel 6.
  • ICP3: Input Capture Pin. The PE2 pin can act as an Input Capture Pin for Timer/Counter3.
  • PCINT26: Pin Change Interrupt source 26. The PE2 pin can serve as an external interrupt source.

• T4/SCL1/PCINT25 – Port E, Bit 1
  • T4: Timer/Counter4 counter source.
  • SCL1: Two-wire Serial Interface1 Clock. When the TWEN bit in TWCR1 is set (one) to enable the two-wire Serial Interface, pin PE1 is disconnected from the port and becomes the Serial Clock I/O pin for the two-wire Serial Interface1. In this mode, there is a spike filter on the pin to suppress spikes shorter than 50 ns on the input signal, and the pin is driven by an open drain driver with slew-rate limitation.
  • PCINT25: Pin Change Interrupt source 25. The PE1 pin can serve as an external interrupt source.

• ACO/ICP4/SDA1/PCINT24 – Port E, Bit 0
  • PE0 can also be used as Analog Comparator output.
  • ICP4: Input Capture Pin. The PE0 pin can act as an Input Capture Pin for Timer/Counter4.
  • SDA1: Two-wire Serial Interface1 Data. When the TWEN bit in TWCR1 is set (one) to enable the two-wire Serial Interface, pin PE0 is disconnected from the port and becomes the Serial Data I/O pin for the two-wire Serial Interface1. In this mode, there is a spike filter on the pin to suppress spikes shorter than 50 ns on the input signal, and the pin is driven by an open drain driver with slew-rate limitation.

Table 17-13 relate the alternate functions of Port E to the overriding signals shown in Figure 17-5.