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NETAJI SHUBHAS INSTITUTE OF TECHNOLOGY

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8085

BASED SCALE

HYPSOMETER

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PROJECT REPORT

ON

RISHABH SRIVASTAVA (141EC15)

SURENDER SINGH (178EC15)

DEPARTMENT OF

ELECTRONICS AND COMMUNICATION

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TABLE OF CONTENTS

1. Acknowledgement… ........................................... 3

2. Project Description… .......................................... 4

3. Block Diagram ..................................................... 5

4. Flow Chart… ....................................................... 6

5. Components Used ............................................. 7

6. Circuit Description… .......................................... 9

7. Schematic… ...................................................... 10

8. Board Layout… ................................................. 12

9. Testing and Debugging… ................................. 13

10. Proposed Gantt Chart… .................................... 16

11. Actual Gantt Chart ............................................. 17

12. Main Program ................................................... 18

13. Photo Gallery. ................................................... 20

14. Future Scope… ................................................. 22

15. References ........................................................ 23

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ACKNOWLEDGEMENT

We would like to thank Prof. Dhananjay V. Gadre for providing us this opportunity to

work on this wonderful project and providing his support and guidance throughout this

project. It would not be possible for us to complete this project without his guidance.

We are thankful to our families and friends who were supporting us all the time for this

project.

We also thank all CEDT members for helping us with difficulties and errors along the

way. At last we are thankful to all those who directly or indirectly help us in completing

this project.

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PROJECT DESCRIPTION

This project titled as “SCALE HYPSOMETER” is based on the basic principles of

Trigonometry. A Scale Hypsometer is a device used to calculate the height of trees,

buildings and many such things. The basic idea of this project is that, if we somehow,

measure the distance between the building and the person and the angle of inclination

from the point he is standing to the top of building then we can calculate the height of

the building.

H = dist * tan(angle)

We are using an ultrasonic sensor which will measure the distance and a potentiometer

which will be used to measure the angle. To measure the angle we use a laser diode

which will be mounted on the potentiometer. On rotating the potentiometer, laser will

start pointing at the object. The analog readings of the potentiometer are then mapped to

give the corresponding angle.

Since ultrasonic wave is a kind of sound wave and sound waves are affected by the

temperature. Therefore a temperature sensor is also used so as to get the corresponding

speed of ultrasonic waves.

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BLOCK DIAGRAM

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FLOW CHART

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COMPONENTS USED

8085: This is an 8-bit microprocessor that can be interfaced with maximum 64K bytes

of memory. It consists of 16-bit address bus and 8 bit data bus that is de-multiplexed

from lower order address bus. These buses help in selecting and transferring data to and

from memory as well as external devices.

8155: The 8155 is a multipurpose programmable device, specifically designed to be

compatible with the 8085 microprocessor. The 8155 includes 256 bytes of R/W memory,

three I/O ports and a timer.

ADC: The ADC 0809 is an 8-bit, 8channel analog to digital converter.

EEPROM: AT28C256 is used as electrically erasable and programmable read only

memory. Its 256K of memory is organized as 32,768 words by 8 bits. The AT28C256 is

accessed like a Static RAM for the read or write cycle without the need for external

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components. It contains a 64-byte page register to allow writing of up to 64 bytes

simultaneously.

LATCH: 74HC574 IC is used as an address latch. It is an 8-bit positive-edge triggered D

type flip-flop with 3 state outputs. The device features a clock and output enable inputs.

LCD, ultrasonic sensor, LM35DT, potentiometer, latch, LM358.

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CIRCUIT DESCRIPTION

The circuit involves usage of the 8-bit 8085 microprocessor, the 8155 for interfacing I/O

devices and an 8-channel ADC-0809.

In the 8155, Port A is used as an input port which takes input from the ADC and Port B

act as output port, which is used to interface with the LCD. Pin PB1 of Port B is used as

an EOC of the ADC. Port C is used as an output port which controls CS, START and

three address line of ADC.

In the 8085, the SID and SOD pins are connected to the ultrasonic sensor. All the

interrupt pins are grounded except RST7.5.

Between each IC, suitable capacitors are introduced in order to reduce fluctuations in

voltage, which in turn prevents damage to the IC’s.

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SCHEMATIC

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BOARD LAYOUT

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TESTING AND DEBUGGING

After successfully soldering the circuit board, these steps were followed during the

testing process:

1. The whole circuit was tested for any wrong connections. All the components were

thoroughly checked using multi-meter for any short-circuit. It was also checked

that all the components were getting proper voltage. After, complete satisfaction,

we moved on to the next step.

2. Sid-Sod testing: A simple assembly language program was burnt into the

EEPROM to check for inputs on the SID pin and checking the same as the output

on SOD pin.

This ensures proper working of 8085 IC and EEPROM.

3. After successfully testing for SID-SOD we move on to run 8155 IC. But initially

it did not work as expected by us. Then we checked the data bus of 8085 using the

MSO. On checking the chip-enable pin of 8155, which is actually an inverting

response of A15 pin of 8085, through MSO it does not come out perfectly inverse

of A15 as shown in fig. After giving so much time, we could not resolve this

problem. Then we took this issue to our mentor, Prof. D.V. Gadre, who suggested

us to use 1K ohm resistor at MOSFET’s drain terminal, instead of 10K ohm which

we were using before as it was slowing down the inverting characteristics of the

MOS inverter we were using for the chip select logic of our RAM+PPI i.e. 8155

an approximate delay of 550 ns(shown in figure) was there when we were using

10k resistor due to which both RAM and ROM were getting selected at the same

instant which was quite a big issue in such a system. Miraculously the tip worked

for us for which we are really thankful to him.

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4. After that LCD program was burnt to EEPROM to test LCD. Here, the LCD is

made to work in 4-bit mode only.

5. After successful working of LCD, the external sensors were interfaced using

ADC. A clock is required for the ADC to work which is shown in fig. and is

generated using timer in 8155.

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50 kHz Clock for ADC

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PROPOSED GANTT CHART

1 30-Apr-18 Final Submission

4 12-Apr-18 Documentation and Video

3 9-Apr-18 Testing and Debugging

2 7-Apr-18 Soldering

15 11-Mar-18 Coding

7 10-Mar-18 Designing the Board Layout

7 10-Feb-18 Laying the Schematic

5 1-Feb-18 Visualisation of the Final Project

2 2-Feb-18 Interfacing 16x2 LCD

2 24-Jan-18 Learning to interface Ultrasonic Sensor

60 2-Jan-18 Studying about 8085

5 11-Jan-18 Getting Approval

1-Jan-18 5 Deciding Project

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ACTUAL GANTT CHART

1 23-May-18 Final Submission

10 24-Apr-18 Documentation and Video

10 7-Apr-18 Testing and Debugging

2 5-Apr-18 Soldering

30 11-Mar-18 Coding

Actual Date

Duration_actual 12 10-Mar-18 Designing the Board Layout

10 7-Feb-18 Laying the Schematic

5 2-Feb-18 Interfacing 16X2 LCD

5 1-Feb-18 Visualisation of the Final Project

2 26-Jan-18 Learning to interface Ultrasonic

Sensor

60 2-Jan-18 Studying about 8085

5 16-Jan-18 Getting Approval

7 8-Jan-18 Deciding Project

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MAIN PROGRAM

A snippet of the assembly code used for this project is:

MAIN:

;read temperature

MVI A,TEMPCHANNEL

CALL ADC

STA TEMP

;print it on lcd

CALL PRINT_TEMP

;read the horizontal distance &print it on lcd

CALL ULTRA

;read angle of inclination from pot

MVI A,POTCHANNEL

CALL ADC

STA INC

;map the value of adc to angle

CALL MAP

;go to lookup table

;compute height and print it on lcd

CALL CALCULATE

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;wait for a delay before taking next set of readings

;else readings will keep on flickering and no one would be able to read it

LXI D,FFFFH

CALL DELAY_MS

LXI D,FFFFH

CALL DELAY_MS

LXI D,FFFFH

CALL DELAY_MS

LXI D,FFFFH

CALL DELAY_MS

;repeat the entire process indefintily

JMP MAIN

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PHOTO GALLERY

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FUTURE SCOPE

This project, although simple, but can be used effectively for demonstrating the

principles of trigonometry and its application in daily life to the school kids. It would

help them have a deeper insight in the lessons they learn in school & help them realize

that the concept is applicable not only in their textbooks and classrooms but also in

reality.

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REFERENCES

[1] National Council of Educational Research and Training, MATHEMATICS- Textbook for Class X. New Delhi, INDIA: NCERT, 2010.

[2] Ramesh Gaonkar, Microprocessor Architecture, Programming and Applications with the 8085, 6th ed.: Penram International Publishing, 2013.

[3] NSIT. (2011) 8085 projects: The Compendium. [Online]. http://8085projects.in/