1
Features
• Compatible with MCS
®
-51 Products
20K Bytes of Reprogrammable Flash Memory
Endurance: 1000 Write/Erase Cycles
4V to 5.5V Operating Range
FullyStaticOperation:0Hzto33MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Eight Interrupt Sources
Programmable Serial Channel
Low-power Idle and Power-down Modes
Interrupt Recovery from Power-down Mode
Hardware Watchdog Timer
Dual Data Pointer
Power-off Flag
Description
The AT89C55WD is a low-power, high-performance CMOS 8-bit microcontroller with
20K bytes of Flash programmable read only memory and 256 bytes of RAM. The
device is manufactured using Atmel’s high-density nonvolatile memory technology and
is compatible with the industry standard 80C51 and 80C52 instruction set and pinout.
The on-chip Flash allows the program memory to be user programmed by a conven-
tional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash
on a monolithic chip, the Atmel AT89C55WD is a powerful microcomputer which pro-
vides a highly flexible and cost effective solution to many embedded control
applications.
The AT89C55WD provides the following standard features: 20K bytes of Flash, 256
bytes of RAM, 32 I/O lines, three 16-bit timer/counters, a six-vector, two-level interrupt
architecture, a full-duplex serial port, on-chip oscillator, and clock circuitry. In addition,
the AT89C55WD is designed with static logic for operation down to zero frequency
and supports two software selectable power saving modes. The Idle Mode stops the
CPU while allowing the RAM, timer/counters, serial port, and interrupt system to con-
tinue functioning. The Power-down Mode saves the RAM contents but freezes the
oscillator, disabling all other chip functions until the next external interrupt or hardware
reset.
Rev. 1921B–MICRO–09/02
8-bit
Microcontroller
with 20K Bytes
Flash
AT89C55WD