Interfacing ICs

8257 DMA Controller

8257 DMA Controller: In microprocessor based systems data transfer can be controlled by either software or hardware. Upto this point we have used program instructions to transfer data from I/O device to memory or from memory to I/O device. To transfer data by 8257 DMA Controller method microprocessor has to do following tasks : To […]

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Interfacing 8251 with 8085

Interfacing 8251 with 8085: Fig. 14.44 shows the Interfacing 8251 with 8085 in I/O mapped I/O technique. Here, RD and WR signals are activated by CPU when IO/M signal is high, indicating I/O bus cycle. The address line A0 is connected to the C/D input .of the 8251A. The RESET and CLK signals are driven

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8251 Usart

8251 Usart: We know that, 8251A is Universal Synchronous, Asynchronous, Receiver, and Transmitter. Therefore 8251 Usart can take place with four different ways. Asynchronous transmission Asynchronous reception Synchronous transmission Synchronous reception These communication modes can be enabled by writing proper mode and command instructions. The mode instruction defines the baud rate (in case of asynchronous

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8251 Block Diagram in Microprocessor

8251 Block Diagram in Microprocessor: Fig. 14.37 shows the 8251 Block Diagram in Microprocessor. It includes : Data bus buffer, Read/Write control logic, modem control, Transmit buffer, Transmit Control, Receiver Buffer and Receiver control. Data Bus Buffer : This tri-state, bi-directional, 8-bit buffer is used to interface 8251 Block Diagram in Microprocessor to the system

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8251 Pin Diagram

8251 Pin Diagram: Fig. 14.36 shows the 8251 Pin Diagram. 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) : A low on

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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

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Serial Communication Interface 8251

Serial Communication Interface 8251: 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

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8255 Interfacing with 8086

8255 Interfacing with 8086: Fig. 14.17 shows the 8255 Interfacing 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

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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)

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8255 Pin Diagram

8255 Pin Diagram: Fig. 14.1 shows the 8255 Pin Diagram of Microprocessor. 8255 Block Diagram: Fig. 14.2 shows the internal 8255 block diagram of 8255 Pin Diagram 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 the

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