8253 INTERFACE

AIM:

                        To study 8253 Timer and verify its modes of operation

APPARATUS REQUIRED:

            1. 8085 – Micro Processor kit

            2. 8253 timer – interface board

            3. Flat ribbon cable

4. Cathode ray oscilloscope [CRO]

MODE–0   INTERRUPT ON TERMINAL COUNT:

           

            The output until be initially low after mode set operation after loading the counter the output will remain low while counting and on terminal count the output will become high until reloaded again.

Set the Channel 0 in mode 0 connect 0 to the denounce circuit and execute the following program.                                          

MODE 0

ADDRESS	OPCODE	LABEL	MENMONIC	COMMENTS
4100	3E, 30	START	MVI A, 30	CHANNEL 0
4102	D3, CE		OUT 0CEH	SS MODE 0
4104	3E, 05		MVI A, 05	LSB OFF
4106	D3, C8		OUT 0C8H	COUT OF COUNT
4108	3E, 00		MVI A, 00	MSB OF COUNT
410A	D3, C8		OUT 0C8H
410C	76		HLT

MODE1

ADDRESS	OPCODE	LABEL	MNEMONICS	COMMENTS
4100	3E, 32	START	MVI A, 32	CHANNEL 0 IN MODE1
4102	DE, CE		OUT 0CEH
4104	3E, 05		MVI A, 05
4106	D3, C8		OUT 0C8H	MSB OF COUNT
4108	3E, 00		MVI A, 00H	TRIGGER
410A	DE, C8		OUT 0C8H
41OC	D3, D0		OUT 0D0H
410E	76		HLT

MODE 2

ADDRESS	OPCODE	LABEL	MNEMONICS	COMMENTS
4100	3E, 36	START	MVI A, 36	CHANNEL 0 IN MODE3
4102	D3, CE		OUT 0CEH
4104	3E, 0A		MVI A, 0A	LSB OF COUNT
4106	D3, C8		OUT 0C8H
4108	3E, 00		MVI A, 00H	MSB OF COUNT
410A	D3, C8		OUT 0C8H
410C	76		HLT

RESULT:

            Thus the programmable timer interface is executed and the results are verified