To generate positive going ramp (or sawtooth) using 8085 microprocessor.

Aim

To generate positive going ramp (or sawtooth) using 8085 microprocessor.

Apparatus:8085 microprocessor kit.

Theory:This program generates a stair case. If we continuously increment a 8 bit counter which is connected to ADC, then it will generate 255 voltage steps of a staircase at its analog output as the counter starts from 0 to 255. After 255th count , the counter returns to zero and again starts incrementing 0 to 255, so DAC generates 255 steps staircase (or ramp), which can be observed on the oscilloscope.

Procedure:There is a 26 pin connector J3. All the lines of 8255 PIO are brought out on this connector

The PIO cards are interfaced through 26 pin FRC flat cable.

1. Connect the PIO card to DYNA -85L (J3) through 26 pin FRC flat cable as shown below:

2. The program for all the PIO cards are given in an EPROM (2732) labeled PIO-MON. Place EPROM in socket U3 of DYNA_85L kit. Do the appropriate jumper setting for 2732 EPROM (Check DYNA-85L Manual for details).
3. The Program can be entered in two ways:

Copy the program from the specified RAM location as: DYNA-85> C 4E00 4EFF C000 Enter

Enter the program given as below:

4. Run the program from C000.

Code for display the message “Program for ramp generation”

C050: 0D 0A 50 52 4F 47 52 41 4D 20 46 4F 52 20 44 41

C060: 43 0D 0A 52 41 4D 50 20 47 45 4E 45 52 41 54 4F

C070: 52 00

[Press Enter]

Program:DYNA85LU> A C000 [Press Enter]

Waveform

Calculation:

Amplitude:

Time Period:

Result:The Sawtooth Waveform was generated and displayed on CRO as: