AT89C51_datasheet

Features

•

80C52 Compatible

– 8051 Instruction Compatible

– Six 8-bit I/O Ports (64 Pins or 68 Pins Versions)

– Four 8-bit I/O Ports (44 Pins Version)

– Three 16-bit Timer/Counters

– 256 Bytes Scratch Pad RAM

– 9 Interrupt Sources with 4 Priority Levels

•

Integrated Power Monitor (POR/PFD) to Supervise Internal Power Supply

• 40 MHz (Vcc 2.7V to 5.5V, both Internal and external code execution)

• 60 MHz (Vcc 4.5V to 5.5V and Internal Code execution only)

– In X2 mode (6 Clocks/machine cycle)

• 20 MHz (Vcc 2.7V to 5.5V, both Internal and external code execution)

• 30 MHz (Vcc 4.5V to 5.5V and Internal Code execution only)

•

64K Bytes On-chip Flash Program/Data Memory

– Byte and Page (128 Bytes) Erase and Write

– 100k Write Cycles

•

On-chip 1792 bytes Expanded RAM (XRAM)

– Software Selectable Size (0, 256, 512, 768, 1024, 1792 Bytes)

•

Keyboard Interrupt Interface on Port 1

•

SPI Interface (Master/Slave Mode)

•

8-bit Clock Prescaler

•

16-bit Programmable Counter Array

– High Speed Output

– Compare/Capture

– Pulse Width Modulator

– Watchdog Timer Capabilities

•

Asynchronous Port Reset

•

Full-duplex Enhanced UART with Dedicated Internal Baud Rate Generator

8-bit Flash

Microcontroller

AT89C51RD2

AT89C51ED2

1. Description

AT89C51RD2/ED2 is high performance CMOS Flash version of the 80C51 CMOS single chip 8-

bit microcontroller. It contains a 64-Kbyte Flash memory block for code and for data.

The 64-Kbytes Flash memory can be programmed either in parallel mode or in serial mode with

the ISP capability or with software. The programming voltage is internally generated from the

standard V

CC

pin.

The AT89C51RD2/ED2 retains all of the features of the Atmel 80C52 with 256 bytes of internal

RAM, a 9-source 4-level interrupt controller and three timer/counters. The AT89C51ED2 pro-

bringing the clock frequency down to any value, including DC, without loss of data.

The AT89C51RD2/ED2 has 2 software-selectable modes of reduced activity and an 8-bit clock

prescaler for further reduction in power consumption. In the Idle mode the CPU is frozen while

the peripherals and the interrupt system are still operating. In the Power-down mode the RAM is

saved and all other functions are inoperative.

The added features of the AT89C51RD2/ED2 make it more powerful for applications that need

pulse width modulation, high speed I/O and counting capabilities such as alarms, motor control,

corded phones, and smart card readers.

Package Flash (Bytes) XRAM (Bytes) Total RAM (Bytes) I/O

2. Block Diagram

3. SFR Mapping

The Special Function Registers (SFRs) of the AT89C51RD2/ED2 fall into the following

categories:

• C51 core registers: ACC, B, DPH, DPL, PSW, SP