8251 programmable/communication interface-microprocessor, Assembly Language

8251 Programmable/Communication Interface

As an instance of a serial interface device let us suppose Intel's 8251 A programmable communication interfaces. The 8251A is diagrammed in given figure. It is capable of being programmed for synchronous / asynchronous communication.  The data that is in buffer and data-out buffer registers share the similar port address. For input, the serial bit stream is arriving on the R x D pin is shifted into the receiver shift register and then the data bits are transferred to the data-in buffer register, where they might be input by the CPU. On the other hand on output the data bits put in the data-out buffer register by the CPU are transferred to the transmitter shift register and, along with the essential synchronization bits, are shifted out through the T x D pin. Among other things the contents of the mode register, which are begin by the executing program, determine whether the 8251A is in synchronous mode or asynchronous mode and the format of the characters being received and transmitted. The control register, which is set by the program, controls the operation of the interface, and the status register makes sure information available to the executing program. Obviously, the sync character registers are for storing the sync characters required for synchronous communication.

1142_8251.jpg

Even though all 7 of the registers on the left side of Figure 4.7 may be accessed by the processor, the 8251A is associated with only 2 port addresses. The C/D pin is linked to the address line AO and AO differentiates the 2 port addresses. The 8251A internally interprets the C/D, RD, and WR signals as follows:

1611_8251 signals.jpg

Posted Date: 10/10/2012 7:45:42 AM | Location : United States







Related Discussions:- 8251 programmable/communication interface-microprocessor, Assignment Help, Ask Question on 8251 programmable/communication interface-microprocessor, Get Answer, Expert's Help, 8251 programmable/communication interface-microprocessor Discussions

Write discussion on 8251 programmable/communication interface-microprocessor
Your posts are moderated
Related Questions
Overview of Intel Pro-Pentium : The 2 chief players in the PC CPU market are Motorola and Intel.  Intel has enjoyed incredible success with its processors since the early 1980

write a Mips program that read a string AND PRINT IT ON THE SCREEN

Intel's 8237 DMA controller : 1) The 8237 contain 4 independent I/O channels 2) It contains 27 registers, 7 of which are system-wide registers and 5 for each channel. 3)

8237 modes : Intel 8237 can be set to four different type of style of transfer: 1) Single - One transfer at a time,  it allow processor access to the bus between transfers

Assembly Language: Inside the 8085, instructions are really stored like binary numbers, not a very good manner to look at them and very difficult to decipher. An assembler is

Perform an extensive web search of popular microcontroller manufacturers (some of the major players) to select a suitable device for the system to control the lighting of a typical

Write a 32-bit program which when run, allows the user to select from a menu: (1)    Enter a Binary Number (2)    Enter a Decimal Number (3)    Enter a Hexadecimal Number

AAM: ASCII Adjust for Multiplication after execution. This instruction converts the product available in the AL into unpacked BCD format.  This follows a multiplication   instruct

SEG : Segment of a Label:- The SEG operator is which is used to decide the segment address of the, variable, label or procedure and substitutes the segment base address in plac

1. Write an assembly program that adds the elements in the odd indices of the following array. Use LOOP. What is the final value in the register? array1 DWORD 10, 20, 30, 40, 50, 6