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Problem – Interface with microprocessor and write an assembly Subtract content of two ports by interfacing with microprocessor. The interfacing happens with the ports of the Microprocessor. The main IC’s which are to be interfaced with are: 1. PPI. 2. PIC. 3. USART. PPI: 82C55 The 82C55 is a popular interfacing component, that can interface any TTL-compatible I/O device to the microprocessor.

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Design a microprocessor system to control traffic lights.

Intel A Programmable Peripheral Interface

Increment lookup table pointer. Select your Language English. In serial communication interface, the interface gets a single byte of data from the microprocessor and sends it bit by bit to other system serially or the interface receives data bit by bit serially from the external systems and converts the data into a single byte and transfers it to the microprocessor.

Thus the capability is niterfacing limited in this type of interfacing. Johns the Baptist C. Hence decoded mode is used. Minimum Mode Configuration of The pins are used to control relay on-off action with the help of relay 88255 circuits. These devices are nothing but a combination of many devices on a single chip. It functions as an input device if it is connected to buffer and as an output device if it is connected to latch.


If not zero, repeat. This interface gets a byte of data from microprocessor and sends it bit by bit to the other systems in simultaneous or parallel fashion. So there is chance of faults and defects. There are two ways in which a microprocessor can connect with outside world or other memory systems.

8255A – Programmable Peripheral Interface

We know that keyboard and Displays are used as communication channel with outside world. While executing an instruction, there is a necessity for the microprocessor to access memory frequently for reading various instruction codes and data stored in the memory. Posted by Dhanoop Bhaskar at 6: A programmable device can be set up to perform specific function by writing a code in the internal register.

Load control word in AL. Your email address will not be published. Here, 4 scan lines are sufficient to scan matrix keyboard and to select display digits. Send data on port A to glow Y1 and Y2.

Send data on port B to glow R3 and R4. Memory requires some signals to read from and write to registers.

The traffic light arrangement is as shown in Fig. Initialize in write display. The peripheral devices includes.

genius IT ians™: programming (part4)

So it is necessary that we interface keyboard and displays with the microprocessor. Send data on port B to glow Y3 and Y4. In this section we discuss many useful applications like keyboard and display interface, traffic light control, printer interface and so on.


Assume persistence of vision to be 0. Check whether count is 0. In simple words, the primary function of a memory interfacing circuit is to aid the microprocessor in reading and writing a data to the given register of a memory chip. Motor is rotated by 1. The control word format of according to hardware connections is: For this purpose an address decoding circuit is used.

Interface an 8 x 4 matrix keyboard to through Motor shown in the circuit has two phases, with center-tap winding. The transistors are selected such that they can source rated current for the windings.

Write an assembly language program to roll message ‘HELL’ from right to left. Output with handshake 2. Initialize in read. Input Output Interfacing Techniques. The interfacing process involves matching the memory requirements with the microprocessor signals.

Debugging a Program in Features of Microprocessor. Initial size in write Display. Maximum Mode Configuration of So we are using a keyboard and monitor as Input and output along with the processor.