SN8F2280 Series
USB 2.0 Full-Speed 8-Bit Micro-Controller
3.1 OVERVIEW........................................................................................................................................... 42
3.2 POWER ON RESET............................................................................................................................... 44
3.3 WATCHDOG RESET............................................................................................................................ 44
3.4 BROWN OUT RESET ........................................................................................................................... 45
3.4.1 BROWN OUT DESCRIPTION........................................................................................................ 45
3.4.2 THE SYSTEM OPERATING VOLTAGE DECSRIPTION............................................................... 46
3.4.3 BROWN OUT RESET IMPROVEMENT......................................................................................... 47
3.5 EXTERNAL RESET .............................................................................................................................. 48
3.6 EXTERNAL RESET CIRCUIT ............................................................................................................. 48
3.6.1 Simply RC Reset Circuit .................................................................................................................. 48
3.6.2 Diode & RC Reset Circuit ............................................................................................................... 49
3.6.3 Zener Diode Reset Circuit............................................................................................................... 49
3.6.4 Voltage Bias Reset Circuit............................................................................................................... 50
3.6.5 External Reset IC............................................................................................................................. 50
4
SYSTEM CLOCK.................................................................................................................................. 51
4.1 OVERVIEW........................................................................................................................................... 51
4.2 CLOCK BLOCK DIAGRAM................................................................................................................. 51
4.3 OSCM REGISTER ................................................................................................................................. 52
4.4 SYSTEM HIGH CLOCK ....................................................................................................................... 53
4.4.1 EXTERNAL HIGH CLOCK............................................................................................................. 53
4.4.1.1 CRYSTAL/CERAMIC............................................................................................................. 54
4.1.1.2 EXTERNAL CLOCK SIGNAL............................................................................................... 55
4.2 SYSTEM LOW CLOCK ........................................................................................................................ 56
4.2.1 SYSTEM CLOCK MEASUREMENT ............................................................................................... 57
5
SYSTEM OPERATION MODE........................................................................................................... 58
5.1 OVERVIEW........................................................................................................................................... 58
5.2 SYSTEM MODE SWITCHING EXAMPLE ......................................................................................... 59
5.3 WAKEUP ............................................................................................................................................... 61
5.3.1 OVERVIEW ..................................................................................................................................... 61
5.3.2 WAKEUP TIME............................................................................................................................... 61
6
INTERRUPT........................................................................................................................................... 62
6.1 OVERVIEW........................................................................................................................................... 62
6.2 INTEN INTERRUPT ENABLE REGISTER ......................................................................................... 63
6.3 INTRQ INTERRUPT REQUEST REGISTER....................................................................................... 65
6.4 GIE GLOBAL INTERRUPT OPERATION .......................................................................................... 66
6.5 PUSH, POP ROUTINE........................................................................................................................... 66
6.6 INT0 (P0.0) & INT1 (P0.1) INTERRUPT OPERATION....................................................................... 68
6.7 T0 INTERRUPT OPERATION.............................................................................................................. 70
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