Datasheet

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AT89C51ID2
4289C–8051–11/05
PCA Watchdog Timer......................................................................................... 51
Serial I/O Port...................................................................................... 52
Framing Error Detection ..................................................................................... 52
Automatic Address Recognition.......................................................................... 53
Registers............................................................................................................. 55
Baud Rate Selection for UART for Mode 1 and 3............................................... 55
UART Registers.................................................................................................. 58
Interrupt System ................................................................................. 63
Registers............................................................................................................. 64
Interrupt Sources and Vector Addresses............................................................ 71
Power Management............................................................................ 72
Introduction......................................................................................................... 72
Idle Mode............................................................................................................ 72
Power-Down Mode ............................................................................................. 72
Registers............................................................................................................. 75
Keyboard Interface ............................................................................. 76
Registers............................................................................................................. 77
2-wire Interface (TWI) ......................................................................... 80
Description.......................................................................................................... 82
Notes .................................................................................................................. 85
Registers............................................................................................................. 95
Serial Port Interface (SPI)................................................................... 98
Features.............................................................................................................. 98
Signal Description............................................................................................... 98
Functional Description ...................................................................................... 100
Hardware Watchdog Timer .............................................................. 107
Using the WDT ................................................................................................. 107
WDT During Power Down and Idle................................................................... 108
ONCE(TM) Mode (ON Chip Emulation) ........................................... 109
Power-off Flag................................................................................... 110
EEPROM Data Memory..................................................................... 111
Write Data......................................................................................................... 111
Read Data......................................................................................................... 113
Registers........................................................................................................... 114
Reduced EMI Mode........................................................................... 115