Datasheet

iv
ATmega325/3250/645/6450
2570K–AVR–04/07
Prescaling and Conversion Timing................................................................... 200
Changing Channel or Reference Selection ...................................................... 202
ADC Noise Canceler......................................................................................... 203
ADC Conversion Result.................................................................................... 207
JTAG Interface and On-chip Debug System ................................. 214
Overview........................................................................................................... 214
TAP – Test Access Port.................................................................................... 214
TAP Controller .................................................................................................. 216
Using the Boundary-scan Chain ....................................................................... 217
Using the On-chip Debug System .................................................................... 217
On-chip Debug Specific JTAG Instructions ...................................................... 218
On-chip Debug Related Register in I/O Memory .............................................. 219
Using the JTAG Programming Capabilities ...................................................... 219
Bibliography ...................................................................................................... 219
IEEE 1149.1 (JTAG) Boundary-scan .............................................. 220
Features............................................................................................................ 220
System Overview.............................................................................................. 220
Data Registers.................................................................................................. 220
Boundary-scan Specific JTAG Instructions ...................................................... 222
Boundary-scan Related Register in I/O Memory .............................................. 223
Boundary-scan Chain ....................................................................................... 224
Boundary-scan Order ....................................................................................... 233
Boundary-scan Description Language Files ..................................................... 245
Boot Loader Support – Read-While-Write Self-Programming..... 246
Boot Loader Features ....................................................................................... 246
Application and Boot Loader Flash Sections.................................................... 246
Read-While-Write and No Read-While-Write Flash Sections........................... 246
Boot Loader Lock Bits....................................................................................... 248
Entering the Boot Loader Program ................................................................... 249
Addressing the Flash During Self-Programming .............................................. 251
Self-Programming the Flash............................................................................. 252
Memory Programming..................................................................... 259
Program And Data Memory Lock Bits .............................................................. 259
Fuse Bits........................................................................................................... 260
Signature Bytes ................................................................................................ 262
Calibration Byte ................................................................................................ 262
Parallel Programming Parameters, Pin Mapping, and Commands .................. 262
Parallel Programming ....................................................................................... 265
Serial Downloading........................................................................................... 274
Programming via the JTAG Interface ............................................................... 279
Electrical Characteristics................................................................ 291