AT89C51RC-33AC ATMEL Corporation, AT89C51RC-33AC Datasheet - Page 8

• Manufacturer Part Number: AT89C51RC-33AC
• Description: 8-bit Microcontroller with 32K Bytes Flash
• Manufacturer: ATMEL Corporation

Table 3a. AUXR: Auxiliary Register
8
AUXR
–
DISALE
EXTRAM
DISRTO
WDIDLE
AT89C51RC
Reserved for future expansion
Disable/Enable ALE
DISALE
0
1
Internal/External RAM access using MOVX @ Ri/@DPTR
EXTRAM
0
1
Disable/Enable Reset out
DISRTO
0
1
Disable/Enable WDT in IDLE mode
WDIDLE
0
1
Address = 8EH
Not Bit Addressable
Bit
Operating Mode
ALE is emitted at a constant rate of 1/6 the oscillator frequency
ALE is active only during a MOVX or MOVC instruction
Operating Mode
Internal ERAM (00H-FFH) access using MOVX @ Ri/@DPTR
External data memory access
Operating Mode
Reset pin is driven High after WDT times out
Reset pin is input only
Operating Mode
WDT continues to count in IDLE mode
WDT halts counting in IDLE mode
–
7
Dual Data Pointer Registers: To facilitate accessing both internal and external data
memory, two banks of 16-bit Data Pointer Registers are provided: DP0 at SFR address
locations 82H-83H and DP1 at 84H-85H. Bit DPS = 0 in SFR AUXR1 selects DP0 and
DPS = 1 selects DP1. The user should always initialize the DPS bit to the appropriate
value before accessing the respective Data Pointer Register.
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 rest under software control
and is not affected by reset.
–
6
–
5
WDIDLE
4
DISRTO
3
–
2
Reset Value = XXX00X00B
EXTRAM
1
DISALE
1920B–MICRO–11/02
0