AT89S53-16AA ATMEL Corporation, AT89S53-16AA Datasheet - Page 7

• Manufacturer Part Number: AT89S53-16AA
• Description: 8-Bit Microcontroller with 12K Bytes Flash
• Manufacturer: ATMEL Corporation

Dual Data Pointer Registers To facilitate accessing exter-
nal data memory, two banks of 16 bit Data Pointer Regis-
ters are provided: DP0 at SFR address locations 82H-83H
and DP1 at 84H-85H. Bit DPS = 0 in SFR WCON selects
DP0 and DPS = 1 selects DP1. The user should always ini-
talize the DPS bit to the appropriate value before accessing
the respective Data Pointer register.
Table 3. WCON—Watchdog Control Register
WCON Address = 96H
Symbol
PS2
PS1
PS0
DPS
WDTRST
WDTEN
Bit
PS2
7
Function
Prescaler Bits for the Watchdog Timer. When all three bits are set to “0”, the watchdog timer has a nominal period of 16
ms. When all three bits are set to “1”, the nominal period is 2048 ms.
Data Pointer Register Select. DPS = 0 selects the first bank of Data Pointer Register, DP0, and DPS = 1 selects the
second bank, DP1
Watchdog Timer Reset. Each time this bit is set to “1” by user software, a pulse is generated to reset the watchdog timer.
The WDTRST bit is then automatically reset to “0” in the next instruction cycle. The WDTRST bit is Write-Only.
Watchdog Timer Enable Bit. WDTEN = 1 enables the watchdog timer and WDTEN = 0 disables the watchdog timer.
PS1
6
PS0
5
reserved
4
Power Off Flag The Power Off Flag (POF) is located at
bit_4 (PCON.4) in the PCON SFR. POF is set to “1” during
power up. It can be set and reset under software control
and is not affected by RESET.
reserved
3
DPS
2
Reset Value = 0000 0010B
WDTRST
1
WDTEN
0
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