4
Atmel AVR390
8463A-AVR-11/11
3.2.2 SPI
To use the SPI interface five pins are required: SCLK, MISO, MOSI, /SS, and GND.
3.2.3 UART
The UART interface needs three pins: TXD, RXD, and GND. A command-response
mechanism is employed on the communication through this port. All the transactions
are initiated by the host.
3.2.4 Single-wire UART
The single-wire UART interface uses two pins: T/R and GND. Through the two pins,
half duplex communication is implemented: only transmit or receive can be performed
at one time.
