89C51 or AT89C51 is an 8-bit microcontroller and belongs to Atmel’s family . Pdf of AT89C51 datasheet & pin diagram are also available at Engineers. AT89C51 datasheet, AT89C51 circuit, AT89C51 data sheet: ATMEL – 8-Bit Microcontroller with 4K Bytes Flash,alldatasheet, datasheet, Datasheet search site. AT89CPC Microchip Technology / Atmel 8-bit Microcontrollers – MCU WAFER 21 MIL BACKGRIND 89C51 – 12MHZ, PDIP, COM TEMP datasheet.

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io – C code to set i/o pins for ATMEL’S AT89C51 microcontroller – Stack Overflow

The original series also known as MCS designed by Intel was discontinued in Which allows for faster development since the flash memory can be erased in a few atmfl. This is what an external programmer looks like. You can buy one hereor you can make one for yourself. You will almost always have the datasheet on hand when working on actual projects.

The purpose of discussing the pins and their functions is to understand what the microcontroller is capable of doing.

Understanding the AT89C51’s pin configuration (Atmel’s 8051 variant)

It might not give you the complete picture of all the datahseet at first, but it is a great place to start from. Once you go through the architecture and internal structure, the picture will get clearer.


Similarly, once you start getting acquainted with more microcontrollers, you will be able to predict the internal architecture to some extent by just looking at the pin configuration.

Pin Name Alternative Function P3.

An interesting fact about these ports is that they are bit addressable along with being byte addressable. Send a high pulse for at least two machine cycles through this tiny metal daatasheet, and you will wipe the registers and set all ports to their default configurations. In AT89C51, the lower 8 bits of the bit address bus are multiplexed with the data bus.

To separate these 8 bits, the ALE pin is kept high. It is an output pin that is used when we are connecting to external extra memory chips. If we are going to use an external dtasheet chip to store the program the code then this pin, which is an output pin, is connected to the pin of the external memory chip. When the program starts to run, the pin is activated twice in each machine cycle.

EA stands for external access enable. When we wish to access the code stored in an external memory chip, the pin should be connected to GND. If we atmell to access on-chip program memory, then it should be connected to Vcc. The has an on-chip oscillator which requires an external clock signal to run.

This clock signal can be supplied via. You must be logged in to post a comment. This site uses Akismet to reduce spam. Learn how your comment data is processed.


It is a form of memory that can be erased in a flash. The name actually comes from that functionality. ag89c51

Before flash memory, data would have dxtasheet be erased one byte at a time. Flash memory is an upgrade, but faster options than flash are also available. Kind of like Batman, a billionaire by day, crime-fighting detective by night. For the purpose of making chips small in size, pins that can be multi-functional are made. Thereby reducing the number of pins and eventually the size of the chip.

When you are working with microcontrollers, you are essentially going to interact with only the pins, on a physical level. If one of your pins is not connected to anything, it can either have a default value of 0 or 1.

ATMEL 89C51 | AT89C51 Microcontroller Pin Diagram & Description

The unconnected pin here is said wtmel be in a floating state. A pull-up resistor is used to ensure that the pin is either low or high, this time for certain. R1 is the external pull-up resistor here. Back to course homepage. Leave a Reply Cancel reply You must be logged in to post a comment.