Getting familiar with Hardware - Sensors

1. Lectures on IoT © IOT-OPEN.EU Consortium
Project Ref. 2016-1-PL01-KA203-026471

2. Erasmus+ disclaimer
This project has been funded with support from the
European Commission. This publication reflects
the views only of the author, and the Commission
cannot be held responsible for any use which may
be made of the information contained therein.

3. Hardware
Sensors

4. Sensors
•Electronic element or subsystem used for detecting the
environmental parameter.

5. Light Sensors
•LDR – Light Dependent Resistor
•Photodiode
•Phototransistor
•Photovoltaic cell

6. • P-N junction (PIN photodiode)
• Photoconductive mode – reverse biased, changes the
current.
• Photovoltaic mode – zero bias, generates voltage
• Avalanche photodiode – increases current by reaching
avalanche breakdown reverse voltage.
Photodiode

7. Phototransistor
•Base-Collector junction - photodiode
•Light generates base current
•Transistor amplifies this current
•Slower than photodiodes

8. LDR
•High resistance in the dark – MΩ
•Low resistance in light – hundreds of
ohms
•Build with semiconductor but not a
P-N junction
•Slower than photodiodes
•Temperature sensitive

9. Thermistor
•NTC (Negative temperature coefficient)
• Decreases resistance while temperature
raises
•PTC (Positive temperature coefficient)
• Increases resistance while temperature
raises

10. Hall effect sensor
•Varies its output voltage in response
to a magnetic field.

11. MEMS sensors
• Microelectromechanical
sensor
•Magnetic field sensors
•Accelerometers
•Gyroscopes
•IMU (inertial measurement unit)
•Analog or digital output

12. Air pressure
•Pressure and temperaturę
•I2C interface

13. GPS
•Global Positioning System
•NMEA protocol
•UART interface

14. Humidity
•Usually humidity +
temperature

15. •Pressure, weight
•Bridge connection
Tensometer

16. Reading sensors
•Analog
• Built-in ADC
•Digital
• Switch
• TWI (I2C)
• SPI
• One-wire
• UART

17. The end ;)