INTERFACING OF WITH In a microprocessor b system, when keyboard and 7-segment LED display is interfaced using ports or latches then the . User Manual for Keyboard and Display Interface Card. Hardware Configuration of With // a) Interface With Interfacing Keyboard Controller with Aparatus. 1. Microprocessor toolkit. 2. Interface board. 3. VXT parallel bus. 4. Regulated D.C power.

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CLK input of is driven from the clock signal of system. This mode is further classified into two output modes.

It has two modes i. Timers and Counters in Microcontroller.

Pin Diagram of Microcontroller. Conditional Statement in Assembly Language Program. If more than 8 characters are entered in the FIFO, then it means more than eight keys are pressed at a time.

Features of Microprocessor. The keyboard consists of maximum 64 keys, which are interfaced with the CPU by using the key-codes.

In the scanned sensor matrix mode, this unit acts as sensor RAM where its each row is loaded with the status of their corresponding row of sensors into the matrix. When it is low, it indicates the transfer of data.


8279 – Programmable Keyboard

The chip select signal, CS is generated using decoding circuit. In the encoded mode, the counter provides the binary count that is to be externally decoded to provide the scan lines for the keyboard and display. Interrupt signal from the is connected to the RST 7. A 1 signal from the is connected to the A 0 input of The line is pulled down with a key closure.


Interrupt signal from the is connected to the interrupt input of Speed Control of DC Motor. Interfacing of with This mode deals with the input given by the keyboard and this mode is further classified into 3 modes. It can also be connected to the RST 5.

These lines are set to 0 when any key is pressed. CLK input of is driven from the clock out of Reset out signal from system is connected to the Reset signal of the Till it is pulled low with a key closure, it is pulled up internally to keep it high. Addressing Modes of Sample and Hold Circuit. To get absolute address, all remaining address lines A 1 -A 15 are used to decode the address for It then sends their relative response of the pressed key to the CPU and vice-a-versa.


The Shift input line status is stored along with every key code in FIFO in the scanned keyboard mode.

Microprocessor – Programmable Keyboard

Encoded mode and Decoded mode. Register Architecture of Microprocessor. Select your Language English.

This unit first scans the key closure row-wise, if found then the keyboard debounce unit debounces the key entry. A 0 signal from the is connected to the A 0 input of These are the output ports for two 16×4 or one 16×8 internal display refresh registers. Leave a Reply Cancel reply Your email address will not be published. In the decoded scan modethe counter internally decodes the least significant 2 bits and provides a decoded 1 out of 4 scan on SL 0 -SL 3.