This post covers the functionality and applications of the 8255 microprocessor, an essential component in interfacing applications. Here, we will discuss what the 8255 microprocessor is, its uses, and its key features compared to other similar microprocessors. In this article, you will find detailed explanations about control words and handshaking in the 8255.
What Is the 8255 Microprocessor?
The 8255 microprocessor is a programmable peripheral interface used primarily for interfacing microprocessors with external devices. Developed by Intel, it provides a means to connect the CPU to peripheral devices like keyboards, displays, and other I/O devices through a parallel communication interface. The 8255 microprocessor can be configured to operate in different modes, allowing for versatile data transfer capabilities.
What Is the Use of an 8255 Microprocessor?
The primary use of the 8255 microprocessor is to manage data transfer between a microprocessor and peripheral devices. It enables communication in various applications, such as:
- Data Acquisition: Collecting and processing data from sensors or other external devices.
- Control Systems: Implementing control logic for devices like motors, displays, and alarms.
- Interfacing Devices: Acting as an intermediary between the microprocessor and peripheral devices, facilitating data exchange.
The 8255 can operate in different modes, such as Mode 0 for simple input/output, Mode 1 for strobed input/output, and Mode 2 for bidirectional data transfer. This flexibility allows for diverse applications in embedded systems and control applications.
What Is the Difference Between 8255 and 8155?
The 8255 and 8155 microprocessors serve similar functions but differ in features and capabilities. The main differences are:
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- Memory Interface: The 8155 includes an additional 128 bytes of RAM, while the 8255 does not have built-in memory.
- Functionality: The 8155 can function both as a programmable peripheral interface and as a memory device, making it more versatile in certain applications.
- Data Lines: The 8255 has 24 I/O lines, while the 8155 includes 20 I/O lines, with additional lines dedicated to memory functions.
These distinctions make the 8155 more suitable for applications requiring integrated memory management alongside peripheral interfacing.
What Is a Control Word in 8255?
A control word in the 8255 microprocessor is a binary code used to configure the device’s operation modes and specify the direction of data transfer for each port. The control word determines whether the ports will function as input or output, and it enables specific features like handshaking or interrupt handling.
The control word is typically written to the control register of the 8255, allowing the microprocessor to set up the desired operating conditions before engaging in data transfer. By customizing the control word, developers can optimize the performance of the 8255 for their specific application needs.
What Is Handshaking in 8255?
Handshaking in the 8255 microprocessor refers to the synchronization process between the CPU and peripheral devices during data transfer. It involves a series of signals exchanged between the devices to ensure that data is transmitted and received correctly.
In the context of the 8255, handshaking is typically implemented using control signals to indicate when the data is ready to be sent or received. This method helps prevent data loss and ensures accurate communication between the microprocessor and peripherals, especially in applications requiring precise timing.
We hope this article helped you learn about the 8255 microprocessor and its applications in interfacing and data transfer. We believe this explanation clarifies the differences between the 8255 and 8155, as well as the concepts of control words and handshaking in the context of the 8255 microprocessor.
