18.2Overview ..............................................................................................................148
18.3Clock Generation .................................................................................................149
18.4Frame Formats ....................................................................................................152
18.5USART Initialization .............................................................................................154
18.6Data Transmission – The USART Transmitter ....................................................155
18.7Data Reception – The USART Receiver .............................................................157
18.8Asynchronous Data Reception ............................................................................161
18.9Multi-processor Communication Mode ................................................................164
18.10Hardware Flow Control ......................................................................................165
18.11Register Description ..........................................................................................167
18.12Examples of Baud Rate Setting .........................................................................171
19 USART in SPI Mode ............................................................................. 176
19.1Features ..............................................................................................................176
19.2Overview ..............................................................................................................176
19.3Clock Generation .................................................................................................176
19.4SPI Data Modes and Timing ................................................................................177
19.5Frame Formats ....................................................................................................178
19.6Data Transfer .......................................................................................................179
19.7Register Description ............................................................................................181
19.8AVR USART MSPIM vs. AVR SPI ......................................................................183
20 USB Controller ..................................................................................... 185
20.1Features ..............................................................................................................185
20.2Overview ..............................................................................................................185
20.3USB Module Powering Options ...........................................................................186
20.4General Operating Modes ...................................................................................189
20.5Power modes .......................................................................................................191
20.6Memory management ..........................................................................................192
20.7PAD suspend .......................................................................................................193
20.8D+/D- Read/write .................................................................................................194
20.9USB Software Operating modes .........................................................................194
20.10Registers Description ........................................................................................195
21 USB Device Operating modes ............................................................ 197
21.1Overview ..............................................................................................................197
21.2Power-on and reset .............................................................................................197
21.3Endpoint reset .....................................................................................................197
iv
ATmega8U2/16U2/32U2
7799D–AVR–11/10
ATMEL [ ATMEL ]
