The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of In-System Programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the indus- try-standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory pro- grammer. By combining a versatile 8-bit CPU with In-System Programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89S51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit timer/counters, a five-vector two-level inter- rupt, serial channel, low-power idle and power-down modes, interrupt recovery from power-down mode, fast programming time, flexible ISP programming (byte and page mode).
The AT89S51 microcontroller combines a CMOS 8‑bit CPU with 4 KB of in‑system programmable flash memory, 128 bytes of internal RAM and 32 programmable I/O pins. It supports a full‑duplex UART, two 16‑bit timer/counters, a watchdog timer and low‑power idle and power‑down modes, making it suitable for a wide range of embedded control applications.
The document provides detailed pin configurations for 40‑lead PDIP, 44‑lead PLCC, 44‑lead TQFP and 42‑lead PDIP packages, a block diagram of the internal architecture, descriptions of each port and special function registers, as well as package dimensions and legal disclaimer information.
| Flash Memory | 4 KB |
|---|---|
| Internal RAM | 128 bytes (8‑bit) |
| Programmable I/O Lines | 32 |
| Timer/Counters | Two 16‑bit |
| UART | Full‑duplex serial channel |
| Operating Voltage | 4.0 V to 5.5 V |
| Maximum Clock Frequency | 33 MHz |
| Watchdog Timer | Present |
| Low‑Power Modes | Idle and Power‑down |
The AT89S51 contains 4 KB of in‑system programmable flash memory.
It provides 32 programmable I/O lines.
The device operates from 4.0 V to 5.5 V.
The microcontroller supports Idle mode and Power‑down mode for reduced power consumption.