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 conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C55WD is a powerful microcomputer which provides 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 also features: high performance, low power consumption, high integration, fully static operation, low cost, high reliability and green packaging.
The AT89C55WD is a low‑power, high‑performance 8‑bit CMOS microcontroller featuring 20 KB of flash memory, 256 bytes of RAM, 32 I/O lines, three 16‑bit timers, and a wide operating voltage range of 4 V to 5.5 V. It supports static operation from 0 Hz up to 33 MHz and includes a hardware watchdog timer, low‑power idle and power‑down modes, and eight interrupt sources.
The document includes a feature summary, pin configuration tables for PDIP, TQFP and PLCC packages, a block diagram, detailed pin descriptions, special function register maps, timer and interrupt register definitions, and package dimension data. Contact information for Atmel worldwide locations is also provided.
| Flash Memory | 20 KB |
|---|---|
| RAM | 256 bytes (8‑bit) |
| I/O Lines | 32 programmable pins |
| Timers | Three 16‑bit timer/counters |
| Operating Voltage | 4 V to 5.5 V |
| Maximum Clock Frequency | 33 MHz |
| Interrupt Sources | Eight |
| Watchdog Timer | Hardware watchdog |
| Power‑saving Modes | Idle and Power‑down |
| Package Type | 40‑lead PDIP |
The AT89C55WD contains 20 KB of reprogrammable flash memory.
It provides 32 programmable I/O lines.
The device operates from 4 V to 5.5 V.
The microcontroller includes three 16‑bit timer/counters.