A car seat is designed to ensure that a parent does not forget a sleeping child in the back of their car. There are two sensors in the car seat. The first one is located directly under the child. The purpose of this sensor is to detect if the seat is being occupied by a child. The other sensor detects if a fob key is 10 meters away from the seat. If the key is over 10 meters away, the sensor will give a high reading. If the key is less then 10 meters away, the key will give a low reading. There are two outputs to this machine. The first is a notification that is sent to the parent if the child is left in the car, and the second is a cooling system that turns on if the child remains in the car while the parent is away. If the child is in the seat and the parent walks away with the fob key, then the circuit will move into a first violation state and a notification will be sent to the parent. If this same reading is made on the next clock cycle, then the machine will move into a second violation state and another notification will be sent. If this happens again the machine will move toward an emergency state where both the cooling system is turned on and the notification is sent. In this emergency state, the cooling system will only be turned off if the child is removed from the seat. However, if a parent approaches a car, within 10 meters, while in the emergency state the machine will not send a notification, but it will keep the cooling system on.

Required:
You are to design TWO finite-state synchronous machines, one being a Moore design and the other being a Mealy design. Depending on the application you have to decide whether you have to synchronize the outputs of the Mealy machine or not. You can use either D flip flops or J-K flip flops for your designs. Mixing different types of flip flops with different trigger edge sensitivity is possible but not recommended. Note that two designs which differ by only the type of flip flop (e. g., J-K vs. D) or number of states (i. e., changing the type of FF or inserting more unnecessary states) is not considered conceptually different.

Infrared sensor is most used sensor in wireless technology where remote controlling functions and detection of surrounding objects/ obstacles are involved. this post will discuss about what is infrared sensor, its working principle, how it works, types, applications, advantages and disadvantages. what is infrared sensor

ir sensor is a simple electronic device which emits and detects ir radiation in order to find out certain objects/obstacles in its range. some of its features are heat and motion sensing.

ir sensors use infrared radiation of wavelength between 0.75 to 1000µm which falls between visible and microwave regions of electromagnetic spectrum. ir region is not visible to human eyes. infrared spectrum is categorized into three regions based on its wavelength i.e. near infrared, mid infrared, far infrared.

wavelength regions of infrared spectrum

near ir – 0.75µm to 3 µm
mid ir – 3 µm to 6 µm
far ir – > 6 µm
1 introduction to infrared sensor

fig. 1 – introduction to infrared sensor

working principle of infrared sensor

infrared sensors works on three fundamental physics laws:

planck’s radiation law: any object whose temperature is not equal to absolute zero (0 kelvin) emits radiation.
stephan boltzmann law: the total energy emitted at all wavelengths by a black body is related to the absolute temperature.
wein’s displacement law: objects of different temperature emit spectra that peak at different wavelengths that is inversely proportional to temperature.
key elements of infrared detection system

the key elements of infrared detection system are:

ir transmitter

ir transmitter acts as source for ir radiation. according to plank’s radiation law, every object is a source of ir radiation at temp t above 0 kelvin. in most cases black body radiators, tungsten lamps, silicon carbide, infrared lasers, leds of infrared wavelength are used as sources.

transmission medium

as the name suggests, transmission medium provides passage for the radiation to reach from ir transmitter to ir receiver. vacuum, atmosphere and optical fibers are used as medium.

ir receiver

generally ir receivers are photo diode and photo transistors. they are capable of detecting infrared radiation. hence ir receiver is also called as ir detector. variety of receivers are available based on wavelength, voltage and package.

ir transmitter and receivers are selected with matching parameters. some of deciding specifications of receivers are photosensitivity or responsivity, noise equivalent power and detectivity.