What is sensor? Most commonly used sensors in embedded systems. Different types of switches and how to interface switch?

2. What are sensors???
A device which provides a usable output in response to
a specified measurand.
A sensor acquires a physical parameter
and converts it into a signal suitable for
processing (e.g. optical, electrical,
mechanical).
Real
world
Senso
r
Intelligent
system

3. Working:
Physical quantity
Electrical Signals
Microcontroller

4. Need for Sensors
 Sensors are omnipresent. They embedded
in our bodies, automobiles, airplanes,
cellular telephones, radios, chemical plants,
industrial plants and countless other
applications.
 Without the use of sensors, there would be
no automation !!

5. Criteria to choose a sensor:
1.Accuracy
2.Environmental Condition
3.Range
4.Resolution
5.Cost
6.Sensitivity
7.Availability
8.Lifetime

6. Types of Robotics sensors:
1. Environment sensors
2. Motion sensors
3. Touch sensors
4. Proximity sensors
5. IR sensors

7. Environmental sensors:
1.Temperature Sensors:
Temperature sensors appear in building, chemical
process plants, engines, appliances, computers, and many
other devices that require temperature monitoring
2.Pressure Sensors:
A pressure sensor measures pressure, typically of gases
or liquids.
3.Humidity Sensors:
Humidity sensing is very important in control systems
for industrial processes and human comfort.

8. Circuit diagram of IR sersor:

9. I R led
Photodiode
I R SENSOR
-
OPAMP
POT
GND
TO
MICROCONTROLLER
PIN
(LOGIC1)
1
+
vcc
Black line

10. I R led Photodiode
I R SENSOR
-
OPAMP
POT
GND
0
+
White line line
TO
MICROCONTROLLER
PIN
(LOGIC 0)
vcc

11. Instructions
 bit_is_set(PINx , Pin no.);
 bit_is_clear(PINx , Pin no.);
 Header File:
compat/deprecated.h

13. Before going into programming mode
lets learn to interface SWITCH :
 Instructions :
1. sbi(PORTX , Pin no.);
2. cbi(PORTX , Pin no.);
Ex : sbi ( PORTD, 7);
cbi ( PORTD, 7);
1. bit_is_set(PINX ,Pin no.);
2. bit_is_clear(PINX ,Pin no.);
Ex: bit_is_set(PIND,2);
bit_is_clear(PIND,2);
VCC
D2
VCC

14. Program:
 #define F_CPU 16000000
 #include <avr/io.h>
 #include <util/delay.h>
 #include<compat/deprecated.h>
int main(void)
 {
 DDRD=0b11110000;
 PORTD=0b00001111;
 while(1)
 {
 if(bit_is_clear(PIND,2))
 sbi(PORTD,6);
else
if(bit_is_clear(PIND,3))
sbi(PORTD,7);
else
cbi(PORTD,6);
cbi(PORTD,7);
}
}

15. else if(bit_is_clear(PIND,3))
sbi(PORTD,7);
else
cbi(PORTD,6);
cbi(PORTD,7);
}
}