AT89C55WD-33AU View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT89C55WD-33AU

8-bit Microcontroller with 20K Bytes Flash

Atmel Corporation 

4.10 EA/VPP

4.11 XTAL1

4.12 XTAL2

External Access Enable. EA must be strapped to GND in order to enable the device to fetch

code from external program memory locations starting at 0000H up to FFFFH. Note, however,

that if lock bit 1 is programmed, EA will be internally latched on reset.

EA should be strapped to VCC for internal program executions.

This pin also receives the 12V programming enable voltage (VPP) during Flash programming.

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

Output from the inverting oscillator amplifier.

5. Special Function Registers

A map of the on-chip memory area called the Special Function Register (SFR) space is shown in Table 5-1.

Table 5-1. AT89C55WD SFR Map and Reset Values

0F8H

0F0H

0E8H

0E0H

0D8H

0D0H

0C8H

0C0H

0B8H

0B0H

0A8H

0A0H

98H

90H

88H

80H

B

00000000

ACC

00000000

PSW

00000000

T2CON

00000000

IP

XX000000

P3

11111111

IE

0X000000

P2

11111111

SCON

00000000

P1

11111111

TCON

00000000

P0

11111111

T2MOD

XXXXXX00

SBUF

XXXXXXXX

TMOD

00000000

SP

00000111

RCAP2L

00000000

AUXR1

XXXXXXX0

TL0

00000000

DP0L

00000000

RCAP2H

00000000

TL1

00000000

DP0H

00000000

TL2

00000000

TH0

00000000

DP1L

00000000

TH2

00000000

TH1

00000000

DP1H

00000000

WDTRST

XXXXXXXX

AUXR

XXX00XX0

0FFH

0F7H

0EFH

0E7H

0DFH

0D7H

0CFH

0C7H

0BFH

0B7H

0AFH

0A7H

9FH

97H

8FH

PCON

0XXX0000

87H

6 AT89C55WD

1921D–MICRO–6/08

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