This document describes generating square and triangular waveforms using a DAC0808 digital-to-analog converter interfaced with an 8085 microprocessor and 8255 programmable peripheral interface. It provides the circuit diagram, theory of operation explaining the DAC's digital input range and analog output range, and flow charts for the algorithms to incrementally increase and decrease the digital output to the DAC to produce each waveform type over multiple clock cycles.

1. Experiment No. 10
Waveform Generation
using DAC0808 and 8085

3. Statement:
1. I/O addresses of PA, PB, PC & CWR are set to 80H-83H
respectively. Interface DAC0808 to Port A of 8255. Write an ALP
to generate:
A) Square Wave B) Triangular Wave
00H
FFH
00H
FFH

4. DAC0808 Interfacing to 8085 using 8255
8085 8255 PA
DAC
0808
CRO

5. Theory:
DAC0808 is 8-bit DAC which means Input is 8-bit Digital & Output is
Analog.
Digital Input Range 00H – FFH (0 to 255 in Decimal)
Analog Output Range 0 – 5V
So, Step Size = 5/255
= 0.01960
≈ 20mV
DAC0808 Interfacing to 8085 using 8255

6. Flow Chart Start
Initialize PA as an OUTPUT Port
Send A to PA
Call Delay
Clear Accumulator
DAC0808 Interfacing to 8085 using 8255
Complement Accumulator

7. Address Label Instruction
7100,1 DELAY: MVI C,FFH
2 DCR C
3,4,5 JNZ UP
6 RET
Address Label Instruction
6B00, 1 MVI A,80H
2,3 OUT CWR
4 XRA A
5,6 OUT PA
7,8,9 CALL DELAY
A CMA
B,C,D JMP UP1
E RST1
UP:
UP1:
DAC0808 Interfacing to 8085 using 8255

8. Flow Chart
Start
Initialize PA as an OUTPUT Port
Send A to PA
Increment Accumulator by 1
X
X
Send A to PA
A=00?
Yes
No
Decrement Accumulator by 1
DAC0808 Interfacing to 8085 using 8255
A=FF?
Yes
No

9. Address Label Instruction
6B00,1 MVI A,80H
2,3 OUT CWR
4 INR A
5,6 OUT PA
7,8 CPI FFH
9,A,B JNZ RISE
4 DCR A
5,6 OUT PA
7,8 CPI 00H
9,A,B JNZ FALL
C,D,E JMP RISE
F RST1
RISE:
DAC0808 Interfacing to 8085 using 8255
FALL: