The Atmel AT89 series is an
Intel 8051
The Intel MCS-51 (commonly termed 8051) is a single chip microcontroller (MCU) series developed by Intel in 1980 for use in embedded systems. The architect of the Intel MCS-51 instruction set was John H. Wharton. Intel's original versions were pop ...
-compatible family of 8 bit
microcontroller
A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs ( processor cores) along with memory and programma ...
s (μCs) manufactured by the
Atmel Corporation
Atmel Corporation was a creator and manufacturer of semiconductors before being subsumed by Microchip Technology in 2016. Atmel was founded in 1984. The company focused on embedded systems built around microcontrollers. Its products included micro ...
.
Based on the Intel 8051 core, the AT89 series remains very popular as general purpose microcontrollers, due to their industry standard instruction set, their low unit cost, and the availability of these chips in DIL (DIP) packages. This allows a great amount of legacy code to be reused without modification in new applications. While less powerful than the newer AT90 series of
AVR RISC
In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set compu ...
microcontrollers, new product development has continued with the AT89 series for the aforementioned advantages.
More recently, the AT89 series has been augmented with 8051-cored special function microcontrollers, specifically in the areas of
USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply ( interfacing) between computers, peripherals and other computers. A broa ...
,
I²C
I2C (Inter-Integrated Circuit, ), alternatively known as I2C or IIC, is a synchronous, multi-controller/multi-target (master/slave), packet switched, single-ended, serial communication bus invented in 1982 by Philips Semiconductors. It is w ...
(two wire interface),
SPI
SPI may refer to:
Organizations
* Indian Protection Service (''Serviço de Proteção ao Índio''), Brazil
* Shotmed Paper Industries, an Egyptian paper manufacturers
* Simulations Publications, Inc., a former US board game publisher
* Sony P ...
and
CAN bus controllers,
MP3
MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere. Orig ...
decoders and hardware
PWM.
Atmel has also created an LP (low power) series of these chips with a "Single Cycle Core", making the execution speed of these chips considerably faster.
AT89 Series Microcontrollers
Port Structures and Operation
All four ports in the AT89C51 and AT89C52 are bidirectional. Each consists of a latch (Special Function Registers P0 through P3), an output driver, and an input buffer. The output drivers of Ports 0 and 2, and the input buffers of Port 0, are used in accesses to external memory. In this application, Port 0 outputs the low byte of the external memory address, time-multiplexed with the byte being written or read. Port 2 outputs the high byte of the external memory address when the address is 16 bits wide. Otherwise the Port 2 pins continue to emit the P2 SFR content. All the Port 3 pins, and two Port 1 pins (in the AT89C52)are multifunctional. The alternate functions can only be activated if the corresponding bit latch in the port SFR contains a 1. Otherwise the port pin is stuck at 0.
External links
Atmel's 8051 family product page, updated link 09/23/2012
References
Atmel microcontrollers
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