Pin Diagram of 8251 Microcontroller

Pin Diagram of 8251 Microcontroller: Fig. 14.36 shows the Pin Diagram of 8251 Microcontroller. Data Bus : Bi-directional, tri-state, 8-bit Data Bus. This pin allow transfer of bytes between the CPU and the 8251A. RD (Read) : A low on this input allows the CPU to read data or status bytes from 8251A WR (Write) […]

Features of 8251 Microcontroller

Features of 8251 Microcontroller: The features of Features of 8251 Microcontroller are namely, 1. The Intel 8251A is an universal synchronous and asynchronous communication controller. 2. It supports standard asynchronous protocol with : 5 to 8 Bit character format odd, even or no parity generation and detection c) Baud rate from DC to 19.2 Kbaud False […]

8251 Serial Interface

8251 Serial Interface: Most of the microprocessors are designed for parallel communication. In parallel communication number of lines required to transfer data depend on the number of bits to be transferred. For example, to transfer a byte of data, 8 lines are required and all 8 bits are transferred simultaneously. Thus for transmitting data over […]

Interfacing 8255 with 8086 Microprocessor

Interfacing 8255 with 8086 Microprocessor: Fig. 14.17 shows the Interfacing 8255 with 8086 Microprocessor and Interfacing 8255 with 8085 Microprocessor in I/O mapped I/O technique. Here RD and WR signals are activated when IO/M signal is high, indicating I/O bus cycle. Reset out signal from 8085 is connected to the RESET signal of the 8255. Interfacing 8255 […]

8255 Programming and Operation

8255 Programming and Operation: The 8255 Programming and Operation are follows Programming in Mode 0: The Ports A, B and C can be configured as simple input or output ports by writing the appropriate control word in the control word register. In the control word, D7 is set to ‘1’ (to define a mode set operation) […]

Pin Diagram of 8255 Microprocessor

Pin Diagram of 8255 Microprocessor: Fig. 14.37 shows the Pin Diagram of 8255 Microprocessor. Block Diagram: Fig. 14.2 shows the internal block diagram of Pin Diagram of 8255 Microprocessor. It consists of data bus buffer, control logic and Group A and Group B controls. Data Bus Buffer: This tri-state bi-directional buffer is used to interface […]