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15 Июля 2017 Infrared Communication Infrared Communication
SPI – Serial Peripheral Interface
SPI (Serial Peripheral Interface) is a full duplex synchronous serial communication interface used for short distance communications. It is usually used for communication between different modules in a same device or PCB. SPI devices communicates each other using a master slave architecture with a single master. Multiple slaves are supported through individual slave select lines.SPI is called as a 4-wire bus as it requires four wires for its communication as shown below. In the case of single slave communications we need only 3 wires, as slave select (SS) is not required. So SPI requires more communication lines in contrast to UART, I2C, USB etc.Hope you got the basic idea of an SPI bus. Now let’s see in little more detailed level like how it is working in hardware level. SPI having relatively very simple hardware compared to other serial communication protocols like UART, I2C etc. Its operation is based on shift registers (usually 8 bit). Each devices (master and slave) uses shift registers to shift data in and out of the system.For the sake of explanation, I omitted Buffer Register. It acts as an interface between user (processor, programmer) and SPI. Usually shift register won’t be directly accessible. So if we need to transmit data, we will write it to the buffer register. So it will automatically written to shift register when it is free and transmission will start. Similarly data is received in the shift register is automatically transferred to buffer register once the reception is complete. We can easily read from it. Thus buffer register will avoid all glitches that can happen if we try to read or write to shift register directly while transmission is taking place.
3 Июля 2017 Infrared Communication Infrared Communication
How do an IR transmitter and receiver work?
The IR transmitter consists of the LED that emits the IR(Infra Red) radiation.This is received by the photo diode, which acts as IR receiver at the receiving end. Since the IR radiation is invisible to human eye it is perfect for using in wireless communication. A electronic remote device mainly consists of this IR transmitter and receiver. A remote control patterns a flash of invisible light which is turned into an instruction and is received by the receiver module. So how it works? The IR signal is modulated during transmission. Modulation means assigning pattern to the data to be sent to the receiver.The most commonly used IR modulation is about 38khz.
3 Июля 2017 Infrared Communication Infrared Communication
Other Uses for Infrared Technology
Although IR no longer plays a large role in transferring files from one computer to the next, it is still valuable technology in other fields.Among them are:Night vision. Infrared amplifies light in low-light situations.Art history. IR technology is used to peek beneath layers of paint on artwork to see what lies beneath.Heating. Infrared can generate and conduct heat. Infrared is popular in saunas and in restaurant food-warming stations.Thermography. IR technology determines ​the relative temperature of objects.Weather forecasting. IR technology is used by weather satellites to determine temperature and cloud formations.
3 Июля 2017 Infrared Communication Infrared Communication
IR wireless
Some engineers consider IR technology to be a sub-specialty of optical technology. The hardware is similar, and the two forms of energy behave in much the same way. But strictly speaking, "optical" refers to visibleelectromagnetic radiation, while "infrared" is invisible to the unaidedeye. To compound the confusion, IR is sometimes called "infrared light."IR wireless is used for short- and medium-range communications andcontrol. Some systems operate in line-of-sight mode; this means that theremust be a visually unobstructed straight line through space between the transmitter(source) and receiver (destination). Other systems operate in diffuse mode,also called scatter mode. This type of system can function when the sourceand destination are not directly visible to each other. An example is a televisionremote-control box. The box does not have to be pointed directly at the set,although the box must be in the same room as the set, or just outside the room with thedoor open.
30 Июня 2017 Infrared Communication Infrared Communication
Communication Using Infrared Technology
Infrared band of the electromagnet corresponds to 430THz to 300GHz and a wavelength of 980nm. The propagation of light waves in this band can be used for a communication system (for transmission and reception) of data. This communication can be between two portable devices or between a portable device and a fixed device.There are two types of Infrared communicationPoint to Point: It requires a line of sight between the transmitter and a receiver. In other words the transmitter and the receiver should be pointed to each other and there shouldn’t be any obstacles between them. Example is the remote control communication.Diffuse Point: It doesn’t require any line of sight and the link between the transmitter and the receiver is maintained by reflecting or bouncing of the transmitted signal by surfaces like ceilings, roof, etc. Example is the wireless LAN communication systemAdvantages of IR communication:Security: Infrared communication has high directionality and can identify the source as different sources emit radiation of different frequencies and thus the risk of information being diffused is eliminated.Safety: Infrared radiation is not harmful to human beings. Hence infrared communication can be used at any place.High Speed data Communication: The data rate of Infrared communication is about 1Gbps and can be used for sending information like video signal.

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