
Rev. 4.00, 03/04, page xxvi of xlvi
10.5.1 Changing the Multiplication Rate........................................................................ 300
10.5.2 Changing the Division Ratio................................................................................ 300
Usage Note........................................................................................................................ 301
10.6
Section 11 Watchdog Timer (WDT).................................................................303
11.1
Feature .............................................................................................................................. 303
11.2
Register Description.......................................................................................................... 304
11.2.1 Watchdog Timer Counter (WTCNT)................................................................... 304
11.2.2 Watchdog Timer Control/Status Register (WTCSR)........................................... 304
11.2.3 Notes on Register Access..................................................................................... 306
11.3
Operation .......................................................................................................................... 307
11.3.1 Canceling Software Standbys.............................................................................. 307
11.3.2 Changing the Frequency...................................................................................... 307
11.3.3 Using Watchdog Timer Mode ............................................................................. 308
11.3.4 Using Interval Timer Mode ................................................................................. 308
Section 12 Timer Unit (TMU)...........................................................................309
12.1
Feature .............................................................................................................................. 309
12.2
Input/Output Pin................................................................................................................ 311
12.3
Register Description.......................................................................................................... 311
12.3.1 Timer Output Control Register (TOCR).............................................................. 312
12.3.2 Timer Start Register (TSTR) ............................................................................... 313
12.3.3 Timer Control Registers 0 to 2 (TCR_0 to TCR_2) ............................................ 314
12.3.4 Timer Constant Registers 0 to 2 (TCOR_0 to TCOR_2)..................................... 317
12.3.5 Timer Counters 0 to 2 (TCNT_0 to TCNT_2)..................................................... 318
12.3.6 Input Capture Register 2 (TCPR_2) .................................................................... 318
12.4
Operation .......................................................................................................................... 319
12.4.1 Counter Operation................................................................................................ 319
12.4.2 Input Capture Function........................................................................................ 322
12.5
Interrupts........................................................................................................................... 323
12.5.1 Status Flag Set Timing......................................................................................... 323
12.5.2 Status Flag Clear Timing..................................................................................... 323
12.5.3 Interrupt Sources and Priorities ........................................................................... 324
12.6
Usage Note........................................................................................................................ 324
12.6.1 Writing to Registers............................................................................................. 324
12.6.2 Reading Registers................................................................................................ 324
Section 13 Realtime Clock (RTC).....................................................................325
13.1
Feature .............................................................................................................................. 325
13.2
Input/Output Pin................................................................................................................ 327
13.3
Register Description.......................................................................................................... 327
13.3.1 64-Hz Counter (R64CNT)................................................................................... 328
13.3.2 Second Counter (RSECCNT).............................................................................. 328