AT89C55WD-33AC ATMEL Corporation, AT89C55WD-33AC Datasheet - Page 7

• Manufacturer Part Number: AT89C55WD-33AC
• Description: 8-bit Microcontroller with 20K Bytes Flash
• Manufacturer: ATMEL Corporation

Table 2. T2CON—Timer/Counter 2 Control Register
Table 3. AUXR: Auxiliary Register
1921B–MICRO–09/02
AUXR
–
DISALE
DISRTO
WDIDLE
T2CON Address = 0C8H
Bit Addressable
Bit
Reserved for future expansion
Disable/Enable ALE
DISALE
0
1
Disable/Enable Reset out
DISRTO
0
1
Disable/Enable WDT in IDLE mode
WDIDLE
0
1
TF2
Address = 8EH
Not Bit Addressable
7
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
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
EXF2
Interrupt Registers: The individual interrupt enable bits are in the IE register. Two priorities
can be set for each of the six interrupt sources in the IP register.
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.
–
7
6
RCLK
–
6
5
–
5
TCLK
4
WDIDLE
4
EXEN2
3
DISRTO
3
TR2
2
–
2
Reset Value = 0000 0000B
Reset Value = XXX00XX0B
C/T2
1
–
1
AT89C55WD
CP/RL2
0
DISALE
0
7