User Manual

iv
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
8271E–AVR–07/2012
18.1Features ..............................................................................................................142
18.2Overview ..............................................................................................................142
18.3Timer/Counter Clock Sources .............................................................................143
18.4Counter Unit ........................................................................................................143
18.5Output Compare Unit ...........................................................................................144
18.6Compare Match Output Unit ................................................................................146
18.7Modes of Operation .............................................................................................147
18.8Timer/Counter Timing Diagrams .........................................................................151
18.9Asynchronous Operation of Timer/Counter2 .......................................................153
18.10Timer/Counter Prescaler ...................................................................................154
18.11Register Description ..........................................................................................155
19 SPI – Serial Peripheral Interface ......................................................... 162
19.1Features ..............................................................................................................162
19.2Overview ..............................................................................................................162
19.3SS
Pin Functionality ............................................................................................167
19.4Data Modes .........................................................................................................167
19.5Register Description ............................................................................................169
20 USART0 ................................................................................................. 172
20.1Features ..............................................................................................................172
20.2Overview ..............................................................................................................172
20.3Clock Generation .................................................................................................173
20.4Frame Formats ....................................................................................................176
20.5USART Initialization .............................................................................................177
20.6Data Transmission – The USART Transmitter ....................................................179
20.7Data Reception – The USART Receiver .............................................................181
20.8Asynchronous Data Reception ............................................................................185
20.9Multi-processor Communication Mode ................................................................188
20.10Examples of Baud Rate Setting .........................................................................189
20.11Register Description ..........................................................................................194
21 USART in SPI Mode .............................................................................. 199
21.1Features ..............................................................................................................199
21.2Overview ..............................................................................................................199
21.3Clock Generation .................................................................................................199
21.4SPI Data Modes and Timing ................................................................................200
21.5Frame Formats ....................................................................................................200
21.6Data Transfer .......................................................................................................203