The intrinsic part of the embedded system is the sensors. Right from simple tv remote to security systems installed at home. They are also becoming important for weather stations to forecast weather parameters(temperature, wind speed, wind direction, solar radiation, and many more) and in IoT(to gather data, sharing data etc).
Definition and Working of Sensors?
The sensor is a module or a chip that is frequently used to detect the changes happening in the (electrical or optical signals) and revert to the controller or processor (i.e microcontroller or microprocessor). i.e the sensor converts the physical parameters (like temperature, distance etc ) to a measurable electrical signal. For smooth working of the sensor a proper power supply and grounding to be provided.
Classification of Sensors
Depending on the type of sensors the controller accepts two types of input
- This type of sensor senses the superficial parameters (like the speed of air, radiations, the intensity of light etc.) and gives analog voltage as an output.
- The output voltage may be in the range of 0 to 5V.
- Logic High is treated as “1” (3.5 to 5V)
- Logic Low is indicated by “0” (0 to 3.5 V).
Analog sensors produce a analog voltage as the output, whereas Digital sensors produce a discrete values(0’s-OFF and 1’s-ON). Where 0 is low voltage(OFF) and 1 is high voltage(ON). These values are called as digital (binary) signals.
- Analog sensors are made up of analog components like resistors, capacitors, operational amplifiers, diodes and transistors.
- Digital sensors consist of logic gates and microcontroller chips.
- Analog signals are much affected by external noise and create errors in the output signal. But digital signals are capable of noisy surroundings and hence digital sensors are preferred over analog ones.
Cons with digital sensors:
Digital sensors have a low calculation range.
For example: some digital temperature sensor series like HYT217 AND SHT has a lower range of temperature measurement. But analog temperature sensors (RTD) have higher step sizes (+ve and -ve temperature). This feature makes analog sensors suitable for a wide temperature range and stability.