14 16-bit Timer/Counter (Timer/Counter1 and Timer/Counter3) ........... 118
14.1 Overview ..........................................................................................................118
14.2 Accessing 16-bit Registers ..............................................................................120
14.3 Timer/Counter Clock Sources ..........................................................................123
14.4 Counter Unit .....................................................................................................123
14.5 Input Capture Unit ............................................................................................125
14.6 Output Compare Units .....................................................................................127
14.7 Compare Match Output Unit ............................................................................128
14.8 Modes of Operation .........................................................................................130
14.9 Timer/Counter Timing Diagrams ......................................................................137
14.10 16-bit Timer/Counter Register Description .......................................................139
15 8-bit Timer/Counter2 with PWM and Asynchronous Operation ...... 150
15.1 Overview ..........................................................................................................150
15.2 Timer/Counter Clock Sources ..........................................................................151
15.3 Counter Unit .....................................................................................................151
15.4 Output Compare Unit .......................................................................................152
15.5 Compare Match Output Unit ............................................................................154
15.6 Modes of Operation .........................................................................................155
15.7 Timer/Counter Timing Diagrams ......................................................................159
15.8 8-bit Timer/Counter Register Description .........................................................161
15.9 Asynchronous operation of the Timer/Counter ................................................166
15.10 Timer/Counter Prescaler ..................................................................................170
16 Output Compare Modulator (OCM1C0A) ........................................... 171
16.1 Overview ..........................................................................................................171
16.2 Description .......................................................................................................171
17 Serial Peripheral Interface – SPI ......................................................... 173
17.1 SS Pin Functionality .........................................................................................177
17.2 Data Modes ......................................................................................................180
18 USART ................................................................................................... 182
18.1 Overview ..........................................................................................................182
18.2 Clock Generation .............................................................................................183
18.3 Frame Formats ................................................................................................186
18.4 USART Initialization .........................................................................................188
18.5 Data Transmission – The USART Transmitter ................................................189
18.6 Data Reception – The USART Receiver ..........................................................191
3
AT90USB64/128
7593A–AVR–02/06
ATMEL [ ATMEL ]
