v
8025I–AVR–02/09
ATmega48P/88P/168P/328P
18.5Frame Formats ....................................................................................................206
18.6Data Transfer .......................................................................................................208
18.7AVR USART MSPIM vs. AVR SPI ......................................................................210
18.8Register Description ............................................................................................211
19 2-wire Serial Interface .......................................................................... 214
19.1Features ..............................................................................................................214
19.22-wire Serial Interface Bus Definition ..................................................................214
19.3Data Transfer and Frame Format ........................................................................216
19.4Multi-master Bus Systems, Arbitration and Synchronization ...............................218
19.5Overview of the TWI Module ...............................................................................221
19.6Using the TWI ......................................................................................................223
19.7Transmission Modes ...........................................................................................227
19.8Multi-master Systems and Arbitration ..................................................................240
19.9Register Description ............................................................................................241
20 Analog Comparator .............................................................................. 246
20.1Overview ..............................................................................................................246
20.2Analog Comparator Multiplexed Input .................................................................246
20.3Register Description ............................................................................................247
21 Analog-to-Digital Converter ................................................................ 250
21.1Features ..............................................................................................................250
21.2Overview ..............................................................................................................250
21.3Starting a Conversion ..........................................................................................252
21.4Prescaling and Conversion Timing ......................................................................253
21.5Changing Channel or Reference Selection .........................................................255
21.6ADC Noise Canceler ...........................................................................................256
21.7ADC Conversion Result .......................................................................................261
21.8Temperature Measurement .................................................................................261
21.9Register Description ............................................................................................262
22 debugWIRE On-chip Debug System .................................................. 267
22.1Features ..............................................................................................................267
22.2Overview ..............................................................................................................267
22.3Physical Interface ................................................................................................267
22.4Software Break Points .........................................................................................268
22.5Limitations of debugWIRE ...................................................................................268
22.6Register Description ............................................................................................268