User Manual

v
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
8271E–AVR–07/2012
21.7AVR USART MSPIM vs. AVR SPI ......................................................................205
21.8Register Description ............................................................................................206
22 2-wire Serial Interface .......................................................................... 209
22.1Features ..............................................................................................................209
22.22-wire Serial Interface Bus Definition ..................................................................209
22.3Data Transfer and Frame Format ........................................................................210
22.4Multi-master Bus Systems, Arbitration and Synchronization ...............................213
22.5Overview of the TWI Module ...............................................................................215
22.6Using the TWI ......................................................................................................217
22.7Transmission Modes ...........................................................................................220
22.8Multi-master Systems and Arbitration ..................................................................233
22.9Register Description ............................................................................................235
23 Analog Comparator .............................................................................. 239
23.1Overview ..............................................................................................................239
23.2Analog Comparator Multiplexed Input .................................................................239
23.3Register Description ............................................................................................240
24 Analog-to-Digital Converter ................................................................ 242
24.1Features ..............................................................................................................242
24.2Overview ..............................................................................................................242
24.3Starting a Conversion ..........................................................................................244
24.4Prescaling and Conversion Timing ......................................................................245
24.5Changing Channel or Reference Selection .........................................................247
24.6ADC Noise Canceler ...........................................................................................248
24.7ADC Conversion Result .......................................................................................252
24.8Temperature Measurement .................................................................................252
24.9Register Description ............................................................................................254
25 debugWIRE On-chip Debug System ................................................... 259
25.1Features ..............................................................................................................259
25.2Overview ..............................................................................................................259
25.3Physical Interface ................................................................................................259
25.4Software Break Points .........................................................................................260
25.5Limitations of debugWIRE ...................................................................................260
25.6Register Description ............................................................................................260
26 Self-Programming the Flash, ATmega 48A/48PA .............................. 261
26.1Overview ..............................................................................................................261