Registers............................................................................................................. 47
Baud Rate Selection for UART for Mode 1 and 3............................................... 47
UART Registers.................................................................................................. 50
Interrupt System ................................................................................. 55
Registers............................................................................................................. 56
Interrupt Sources and Vector Addresses............................................................ 63
Keyboard Interface ............................................................................. 64
Registers............................................................................................................. 65
Serial Port Interface (SPI) ................................................................... 68
Features.............................................................................................................. 68
Signal Description............................................................................................... 68
Functional Description ........................................................................................ 70
Hardware Watchdog Timer ................................................................ 77
Using the WDT ................................................................................................... 77
WDT During Power-down and Idle ..................................................................... 78
ONCE™ Mode (ON Chip Emulation) .................................................. 79
Power Management ............................................................................ 80
Reset .................................................................................................................. 80
Reset Recommendation to Prevent Flash Corruption ........................................ 82
Idle Mode............................................................................................................ 82
Power-down Mode.............................................................................................. 82
Power-off Flag ..................................................................................... 84
Reduced EMI Mode ............................................................................. 85
Flash EEPROM Memory ..................................................................... 86
Features.............................................................................................................. 86
Flash Programming and Erasure........................................................................ 86
Flash Registers and Memory Map...................................................................... 87
Flash Memory Status.......................................................................................... 90
Memory Organization ......................................................................................... 90
Bootloader Architecture ...................................................................................... 91
ISP Protocol Description..................................................................................... 95
Functional Description ........................................................................................ 96
Flow Description ................................................................................................. 97
API Call Description.......................................................................................... 105
Electrical Characteristics ................................................................. 107
Absolute Maximum Ratings ..............................................................................107
ii
xxxxA–8051–10/06
ATMEL [ ATMEL ]
