Ask Question, Ask an Expert


Ask Electrical & Electronics Expert

1. Introduction

Intelligent homes are becoming increasingly popular as cost/performance ratio of microcontrollers is continuously dropping.  These systems incorporate a variety of transducers to detect and transmit status of the home to a supervisory microcomputer. Heating, lighting, security and other parameters are usually controlled by the microcomputer to give a comfortable and safe environment for the residents.

The block diagram of a simple home automation system is demonstrated below:

1242_Block diagram of automation system.jpg

2. Input and output connections

Details of connections to the microcontroller input and output ports are describeed below:

Analogue inputs:

Light Intensity Sensor (LDR) is connected to channel 0 of ADC (RA0).
Manual Control (potentiometer) is connected to channel 1 of ADC (RA1).

Analogue outputs:

Intensity of light emitted by the LED is controlled by PWM1 output (RC1).
Intensity of light emitted by the LED is controlled by PWM2 output (RC2).

Digital outputs:

LEDs connected to RC5 is used specify that a security link is broken.
RB0-RB5 outputs are connected to LCD.

Digital inputs:

RC3 switch is used to set desired ambient light on RC1 (light 1).
All window and door contacts are wire OR-ed and connected to RC4 input.
RC6 switch is used to increment security code from 0-9
RC7 is used to enter any of the three digit security code.

Table below shows the function of each bit of PORTC.
Bit number      Connection               Function
0                      Not used                    X
1                  PWM1 output               Controlled by Potentiometer (POT)
2                  PWM2 output               Controlled by LDR
3                 Sets light intensity         When held high, the desired ambient light 1 can be set
4                 Security loop                 High indicates a security breach
5                 Alarm                           Flashing LED
6                 Security code entry        High-Low transition increments code by one
7                  Enter code                   High-low transition enters one of 3 security digits

3. Objective:

To develop a ‘C’ program to emulate the intelligent home and evaluate its operation using E-BLOCK boards in the T5/03 Embedded Systems laboratory.

4. Purpose:

1. To prepare a structured and annotated ‘C’ program.
2. To provide evidence of the development of each stage of the program. This will consist of producing a logbook and a formal report.
3. To introduce new ideas or improvements to the system.

5. Tasks

The computer performs the following tasks.

1. The intensity of two lights is controlled either manually from potentiometer (dimmer mode) or automatically by measuring the intensity of ambient light using the LDR and adjusting the light output.

a) The intensity of LED connected to RC1 is adjusted by potentiometer. Press and hold RC3 switch and adjust the potentiometer from 0-5 V and show the set intensity on first line one of the LCD. The LED should light up to the required intensity when RC3 is released.

b) Intensity of LED connected to RC2 is controlled automatically by measuring the ambient light. When LDR is covered, the LED lights up to its maximum intensity (about 5 V) and turn off when uncovered. As you move your hand over the LDR, the intensity of the LED should change accordingly.

2. Contacts on the windows and doors are linked to form a continuous loop. RC4 is connected to the loop. When the window or door opens, voltage on the loop changes to 5V. This can be simulated by pressing the switch connected to RC4. A high on this pin indicates a security breach if the system is armed.

3. Security system could be armed and disarmed by entering a 3-digit code. Press the switch connected to RC6 repeatedly to change the first digit of the code from 0-9 as shown on the second line of the LCD When the first digit is displayed on the LCD, press the switch connected to RC7 to enter the digit and move to the next digit. After all three digits are entered, the LED connected to RC5 is turned on to indicate the security system is armed. The system can be disarmed in a same manner by entering a different code. Use following codes for the security system:

To arm the system: 123
To disarm the system: 230
The codes should be cleared after they have been entered for security reasons.

4. When the security loop is broken while the system is armed, the LED connected to RC5 must start to flash at a regular intervals (e.g. twice /second) for 30 seconds. During this period if the system is disarmed the LED must stop flashing and return to its off status. Though, if it is not disarmed in time then the system must automatically disarm itself.
Use Timer 0 in interrupt mode for flashing the RC5 LED.
Use Timer 1 in interrupt mode for timing 30 seconds.

7. Evidence
1- Formal report and logbook kept while developing

Electrical & Electronics, Engineering

  • Category:- Electrical & Electronics
  • Reference No.:- M91718

Have any Question? 

Related Questions in Electrical & Electronics

A a continuous-time signal xt cospi2p is sampled every t

(a) A continuous-time signal x(t) = cosπ2p is sampled every T seconds, resulting in the discrete-time signal x[n] = x(nT) Determine whether the sampled signal is periodic for (b) For those sampled signals in part (a) tha ...

An automotive alternator is rated 500 v-a and 20 v it

An automotive alternator is rated 500 V-A and 20 V. It delivers its rated V-A at a power factor of 0.85. The resistance per phase is 0.05 Ω, and the field takes 2 A at 12 V. If friction and windage loss is 25 W and core ...

Repeat given problem if the dielectric is paraffincoated

Repeat given Problem if the dielectric is paraffincoated paper. Problem Find the capacitance of a parallel plate capacitor if the area of each plate is 0.075 m2 and the distance between the plates is 1.77 mm. The dielect ...

Consider the circuit in given figure with transistor

Consider the circuit in given Figure with transistor parameters, h FE  = 120, V BE  (on) = 0.7 V, and V A  = ∞. Using nodal analysis, determine the input resistance R i f .

The mean breaking strength of cotton threads must be at

The mean breaking strength of cotton threads must be at least 215 grams for the thread to be used in a certain garment. A random sample of 50 measurements on a certain thread gave a mean breaking strength of 210 grams an ...

For the circuits of given figure find the voltage across

For the circuits of given figure, find the voltage across and charge on each capacitor after each capacitor has charged to its final value.

A 2microf capacitor is charged to 12 v and then connected

A 2µF capacitor is charged to 12 V and then connected across a resistor of 100 Ω. (a) Determine the initial energy stored in the capacitor. (b) Determine the energy stored in the capacitor after two time constants have e ...

The term baud gives the signaling rate in symbols per

The term baud gives the signaling rate in symbols per second. For binary systems signaling rate in bauds is equivalent to data rate in bits per second because in a binary system the signaling element takes on one of two ...

The input to a filter is a discrete-time zero-mean random

The input to a filter is a discrete-time, zero-mean, random process whose autocorrelation function is for some constant such that   We wish to filter this process so that the output of the filter is white. That is, we wa ...

Consider the system where the neutral and ground wires are

Consider the system where the neutral and ground wires are bonded at the customer's side. Assume that the neutral wire from the utility has a resistance of 2Ω; the neutral wire is grounded at the source side where the gr ...

  • 4,153,160 Questions Asked
  • 13,132 Experts
  • 2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

A cola-dispensing machine is set to dispense 9 ounces of

A cola-dispensing machine is set to dispense 9 ounces of cola per cup, with a standard deviation of 1.0 ounce. The manuf

What is marketingbullwhat is marketing think back to your

What is Marketing? • "What is marketing"? Think back to your impressions before you started this class versus how you

Question -your client david smith runs a small it

QUESTION - Your client, David Smith runs a small IT consulting business specialising in computer software and techno

Inspection of a random sample of 22 aircraft showed that 15

Inspection of a random sample of 22 aircraft showed that 15 needed repairs to fix a wiring problem that might compromise

Effective hrmquestionhow can an effective hrm system help

Effective HRM Question How can an effective HRM system help facilitate the achievement of an organization's strate