Netaji Subhas Institute Of Technology

Microprocessors Lab EC-316

Automatic Controlled Cat Feeder Using

8085 uP

By: Jeeshan Ali (71/EC/13)

Laxman Verma (88/EC/13)

Aim

To design and construct an automatic controlled cat feeder using microprocessor 8085.

Synopsis

Pets, just like humans, need a regular supply of liquids throughout the day. However, giving

pet milk, especially cats, can be tedious, since if the supply of milk is unregulated, the pet may

overfeed itself.

This project aims at rectifying this issue by providing the pet a means to feed itself and at the

same time, keep the milk supply regulated.

Description:

This project is aimed at making a dispenser controller for pets that operates exclusively by

the pet’s actions and takes human involvement out of the equation. When the switch on the

Milk Dispenser Controller is pressed, the unit will interact with the milk dispenser and cause

the dispenser’s pump to start for a short duration, enabling the milk to seep down into a

container below.

This project uses an 8085 microcontroller to implement the controlling mechanism. The

Controller unit has, apart from the peripherals necessary for the 8085 microprocessor to

function, an external switch, acting as an input, and electromagnet, acting as an output.

When the switch is pressed by a user, the 8085, which is maintaining the timer, is

interrupted and the electromagnet is magnetized. After a specific duration has passed, the

electromagnet is demagnetized, while the timer continues to count down. The

microprocessor monitors this process so that it can be repeated (like 2 times within a 10min

time frame. After the switch is pressed 2 times, the microcontroller disables the interrupt.

And after 10min has passed by, the microcontroller repeats the whole process).

Block Diagram:

2. Using 8085 in Automatic Controlled Cat Feeder (ACCF)

Our project utilized the RST 7.5 interrupt facility and the SOD pin of the 8085.

A switch is connected at the interrupt pin that, when pressed by the pet, gives a high to the 8085 interrupt pin. The interrupt service routing of RST 7.5 makes the SOD pin high. This pin is connected to a relay that then connects an externally placed pump to its supply, prompting the pump to start and dispense milk.

The regulation function of the ACCF is carried internally by the microprocessor that maintains a timer for 5 min and allows for a maximum of 3 interrupts within this 5 min time frame, each interrupt opening the valve for 30sec.

The schematic, calculation and code are given below:

3. Schematic

4. BOARD FILE

5. CALCULATIONS

The code we will be using for the delay will involve a register pair, and is as follows:

LXI B,0FFFFH

LOOP4: DCX B

MOV A,C

ORA B

JNZ LOOP4

The MPU runs on a 4MHz crystal and thus, the calculations are as follows:

Clock Frequency (F) = 2MHz

T states in loop (T)= 24

Value of Register Pair = (65535)10

Therefore: Time Delay (TL) = (T x 65535 / F)

=0.78642 sec

For a Time Delay of 30sec : Value of Register = 30/ TL

= (38)10

= (26)16

For a Time Delay of 5min: Value of Register = 300/TL

= (383)10

= (17F)16

the final code comes out as:

6.CODE

.ORG 0000H

JMP START

.ORG 003CH

JMP SERV

.ORG 0050H

SERV: NOP

MVI A,0CBH

SIM

CALL DELAY

MVI A,5BH

SIM

MVI A,4BH

SIM

DCR L

JZ DISINT

EI

DISINT: RET

DELAY: MVI H,026H

LOOP2: DCX B

MOV A,C

ORA B

JNZ L111OOP2

LXI B,0FFFFH

DCX D

DCR H

JNZ LOOP2

RET

.ORG 0100H

START: LXI SP, 83FFH

MVI A,0BH

SIM

MVI A,4BH

SIM

EI

MVI L,03H

LXI D,017FH

LOOP3: LXI B,0FFFFH

LOOP4: DCX B

MOV A,C

ORA B

JNZ LOOP4

DCX D

MOV A,E

ORA D

JNZ LOOP3

JMP START

Some observations on the code: 1. The register pairs BC and DE are used for the main 5min counter, while registers BC

and H are used for the 30sec counter. Reg L is used to maintain the number of interrupts

left for the 3 count mark.

2. The subroutine continues the same counter as that of the main progam, and at the

same time, decrements its 30sec counter.

3. The program also has provisions to continue the SOD high for a full 30sec, even if the

interrupt is given with a time of <30sec left on the 5min counter.

Here are few images of our project

7.BIBILOGRAPHY

GAONKAR, R. S., & GAONKAR, R. S. (1996). Microprocessor architecture, programming, and applications with the 8085.

DATASHEETS

www.alldatasheet.com/datasheet-pdf/pdf/27996/TI/74LS139.html

http://www.datasheetarchive.com/8085%20opcode-datasheet.html

datasheet.octopart.com/REG1117-3.3-Texas-Instruments-datasheet-5435934.pdf