Interfacing of 4x4 Matrix Keyboard and 4 Digit 7 Segment Display - Free Electronic Projects & 8085 Projects

10/1/13

Interfacing of 4x4 matrix keyboard and 4 digit 7 segment display - Free Electronic projects & 8085 projects

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Interfacing of 4×4 matrix keyboard and 4 digit 7 segment display Nov - 19 - 2009

Statement: Interface 4 x 4 matrix keyboard and 4 digit 7-segment display and write an tssembly language program to read keycode of the pressed key and display same key on the 7 segment display. HARDWARE FOR 4×4 MATRIX KEYBOARD & 4 DIGIT 7 SEGMENT DISPLAY INTERFACE Fig. shows interfacing diagram. Here, 4 scan lines are sufficient to scan matrix keyboard and to select display digits. Hence decoded mode is used.

SOFTWARE FOR 4×4 MATRIX KEYBOARD & 4 DIGIT 7 SEGMENT DISPLAY INTERFACE To display 1 to 8 numbers on the eight 7-segment digits we have to load 7-segment codes for 1 to 8 numbers in the corresponding display locations. 8085projects.info/interfacing-of-4x4-matrix-keyboard-and-4-digit-7-segment-display.html

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The three steps needed to write the software are: Step 1: Find keyboard/display command word.

Step 2: Find program clock command word

Step 3: Find Read FIFO/sensor RAM command word.

Step 4: Find Write FIFO RAM command word.

Source program:

Flowchart for Source Program and Interrupt Service Routine

MVI A, 00H : Initialize keyboard/display in encoded OUT 81H : scan keyboard 2 key lockout mode MVI A, 34H OUT 81H : Initialize pre-scalar count MVI A, 0BH : Load mask pattern to enable RST 7.5 SIM : mask other interrupts EI : Enable Interrupt HERE: JMP HERE : Wait for the interrupt

Interrupt service routine: MVI A, 40H : Initialize 8279 in read FIFO RAM mode OUT 81H IN 80H : Get keycode MVI H, 62H : Initialize memory pointer to point MOV L, A : 7-Segment code MVI A, 80H : Initialize 8279 in write display RAM mode OUT 81H MOV A, M : Get the 7 segment code OUT 80H : Write 7-segment code in display RAM EI : Enable interrupt RET : Return to main program Related Programs (Click down) 8085projects.info/interfacing-of-4x4-matrix-keyboard-and-4-digit-7-segment-display.html

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Generate and display BCD up counter with frequency 1Hz Generate and display BCD down counter Generate and display the contents of decimal counter Debug the delay routine

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Categories 8085 Microprocessor 8086 Microprocessor 555 Circuits Agricultural Automation Circuits Audio Circuits Automotive Circuits Basic Circuits Communication Circuits Control circuits Converting Circuits DIY Circuits Electronic Maintanance Circuits Elevator control circuit Fan circuit 8085projects.info/interfacing-of-4x4-matrix-keyboard-and-4-digit-7-segment-display.html

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Interfacing of 4x4 Matrix Keyboard and 4 Digit 7 Segment Display - Free Electronic Projects & 8085 Projects

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