ATmega48/88/168
21.22-wire Serial Interface Bus Definition ..................................................................210
21.3Data Transfer and Frame Format ........................................................................211
21.4Multi-master Bus Systems, Arbitration and Synchronization ...............................214
21.5Overview of the TWI Module ...............................................................................217
21.6Using the TWI ......................................................................................................219
21.7Transmission Modes ...........................................................................................223
21.8Multi-master Systems and Arbitration ..................................................................236
21.9Register Description ............................................................................................237
22 Analog Comparator .............................................................................. 242
22.1Overview ..............................................................................................................242
22.2Analog Comparator Multiplexed Input .................................................................242
22.3Register Description ............................................................................................243
23 Analog-to-Digital Converter ................................................................ 245
23.1Features ..............................................................................................................245
23.2Overview ..............................................................................................................245
23.3Starting a Conversion ..........................................................................................247
23.4Prescaling and Conversion Timing ......................................................................248
23.5Changing Channel or Reference Selection .........................................................250
23.6ADC Noise Canceler ...........................................................................................251
23.7ADC Conversion Result .......................................................................................256
23.8Register Description ............................................................................................256
24 debugWIRE On-chip Debug System .................................................. 261
24.1Features ..............................................................................................................261
24.2Overview ..............................................................................................................261
24.3Physical Interface ................................................................................................261
24.4Software Break Points .........................................................................................262
24.5Limitations of debugWIRE ...................................................................................262
24.6Register Description ............................................................................................262
25 Self-Programming the Flash, ATmega48 ........................................... 263
25.1Overview ..............................................................................................................263
25.2Addressing the Flash During Self-Programming .................................................264
25.3Register Description ............................................................................................268
26 Boot Loader Support – Read-While-Write Self-Programming, ATmega88 and ATmega168
270
26.1Features ..............................................................................................................270
v
2545M–AVR–09/07
ATMEL [ ATMEL ]
