ATXMEGA128D4 Datasheet, PDF (47/100 Pages) ATMEL Corporation – 8/16-bit AVR XMEGA D4 Microcontroller

27.1.5 Communication functions
27.1.6
SCL
SDA
XCKn
RXDn
TXDn
SS
MOSI
MISO
SCK
Serial Clock for TWI
Serial Data for TWI
Transfer Clock for USART n
Receiver Data for USART n
Transmitter Data for USART n
Slave Select for SPI
Master Out Slave In for SPI
Master In Slave Out for SPI
Serial Clock for SPI
Oscillators, Clock and Event
27.1.7
TOSCn
XTALn
Debug/System functions
Timer Oscillator pin n
Input/Output for inverting Oscillator pin n
RESET
PDI_CLK
PDI_DATA
Reset pin
Program and Debug Interface Clock pin
Program and Debug Interface Data pin
XMEGA D4
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8135G–AVR–08/10