Datasheet

iv
7593L–AVR–09/12
AT90USB64X/128X
19 USART ................................................................................................... 177
19.1 Overview ...........................................................................................................177
19.2 Clock generation ...............................................................................................178
19.3 Frame formats ...................................................................................................180
19.4 USART initialization ...........................................................................................181
19.5 Data transmission – The USART transmitter ....................................................182
19.6 Data reception – The USART receiver ..............................................................185
19.7 Asynchronous data reception ............................................................................189
19.8 Multi-processor Communication mode ..............................................................192
19.9 USART register description ...............................................................................193
19.10 Examples of baud rate setting .........................................................................198
20 USART in SPI mode ............................................................................. 202
20.1 Overview ...........................................................................................................202
20.2 Clock generation ...............................................................................................202
20.3 SPI data modes and timing ...............................................................................203
20.4 Frame formats ...................................................................................................203
20.5 Data transfer ......................................................................................................205
20.6 USART MSPIM register description ..................................................................207
20.7 AVR USART MSPIM vs. AVR SPI ....................................................................209
21 2-wire serial interface .......................................................................... 211
21.1 Features ............................................................................................................211
21.2 2-wire Serial Interface bus definition .................................................................211
21.3 Data transfer and frame format .........................................................................212
21.4 Multi-master bus systems, arbitration and synchronization ...............................215
21.5 Overview of the TWI module .............................................................................216
21.6 TWI register description ....................................................................................219
21.7 Using the TWI ....................................................................................................222
21.8 Transmission modes .........................................................................................225
21.9 Multi-master systems and arbitration .................................................................239
22 USB controller ...................................................................................... 241
22.1 Features ............................................................................................................241
22.2 Block diagram ....................................................................................................241
22.3 Typical application implementation ...................................................................242
22.4 General operating modes ..................................................................................246
22.5 Power modes ....................................................................................................250