Embedded Systems: microprocessors and microcontrollers

An embedded system is a type of computer that can perform a few specialised tasks. This design is contrary to the normal computer that is designed to perform a number of operations that are in many cases unrelated to each other. Embedded systems are present in many of the devices that are used today and act as their control units. The main issue with embedded systems is their optimality in the terms of cost, space and power consumption etc. as, there is no focus on increasing the functionality of the device. The term embedded system can thus, be used to refer to devices that perform certain specific functions and cannot be used to perform others by loading applications on them. Here are a few characteristic features of embedded systems: Many of the embedded systems have several hardware restraints as they have to process real time inputs and must also be…

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Better performance with AVR XMEGA microcontrollers

It seems that ATMEL do not want to limit the AVR branch with 20MIPS AVR microcontrollers. Recently they introduced new AVR microcontroller family – XMEGA – which is still based on AVR core but has a higher performance along with low power feature. AVR microcontrollers are really optimal where high performance is needed with relatively low code size. Probably XMEGA microcontrollers will fill the gap between standard AVRs and AVR32 microcontrollers. XMEGA microcontrollers are featured with: 2nd generation picoPower technology; faster and innovative inter-peripheral communication; 4 channel DMA controller; Real Time Clock; 8 Event System channels; fast 12-bit and DAC; Cryptography support for AES and DES.

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Encoding and modulation of digital signals

We know that digital signals are stored as binary numbers in memory cells. Let’s see how these digital signals can be transferred in other words – how they can be encoded in to electrical signal shape. When signal has to be sent it has to be modulated. Pulse Code Modulation (PCM) Probably simplest and most common modulation method is pulse code modulation (PCM). In CPM coding information is modulated as voltage levels. If supply voltage is 5V, then binary”1″ is represented as +5V while 0 as 0V level. Only two voltage levels are used to modulate signal. Signal can be sent in parallel (bus mode) or serial mode. In parallel mode whole (let’s say 8 bit) signal can be sent at once via 8 wires, while in serial mode data has to be sampled in time. This transmission method is most popular in embedded systems, for instance, ADC sends converted…

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DSP processors and their characteristics

The processing of the various signals is carried out through implements that are together called as DSP hardware. This includes the hardware that is used for transmission of signals, various devices that are used to enhance or filter the signals, analogue to digital and digital to analogue converters and other processing equipment such as computers. Among the hardware mentioned above, digital signal processors are the ones in which the actual processing takes place. Usually the digital signal processors today have the following characteristics: They are equipped to handle real time processing i.e. they can give the optimal performance even when streaming data is being fed into them. The memories that are used to store programs are different from the ones used to store data. They do not provide hardware that supports multitasking. It can be used as a direct memory access device in supporting or host environments. They take analogue…

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Printed Circuit Board (PCB) Technologies

The term circuit technology usually refers to the various techniques that used in the manufacture of electrical circuits. A large number of devices that are used today make use of printed circuit boards (PCBs). These devices provide a mechanical support for the various components present within the given device and also, the electrical connections between the components. The electrical connections present on the PCB are made out of copper sheets that are laminated on a non-conducting material. Initially a large copper sheet is laminated on the board and then the sections that are not required are removed. Various techniques are used for removal of unwanted copper. Some of them are: Silk Screen Printing: In this technique, an etching resistant ink is applied on those areas that are required and the remaining part is etched off. Photoengraving: Here a photo mask of the circuit required is prepared using desired software and…

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Biosignal Properties

The term Biosignal refers to all the signals that are being generated in the human body or any other living organism or more specifically it is used to represent all those signals from living organisms that are monitored to obtain certain useful information. Primarily, the term refers to signals that are electrical in nature but, some non-electric signals are monitored as well. Typically, the changes in potential difference across a certain tissue in the body are measured in case of bio-electric signals. Let us have a look at few of the properties of biosignals generated by the human body that are analysed to obtain information: In case of Electroencephalography, the activity of the human brain is monitored. Usually, at a synapse (junctions between the cells of the nervous system), flow of ions takes place. This results in the formation of various signals that are used by the body to transfer…

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Digital Signal Processing – Applications

Digital signal processing is the technique used to analyse various digital signals and obtain information form the same. It is also used for transfer of information from one place to another and also involves conversion in between analogue and digital signals. It finds its application in various areas ranging from broadcasting to medicine. Let us have a look at some of the applications of the same. Biomedical Applications: DSP is used extensively in the field of biomedicine. In it, the various signals that are generated by the different organs in the human body are measured in order to find information regarding the health of the same. For example, in case of electrocardiograms, the electric signals generated by the heart are measured. Similarly, the activity of the brain is monitored by electroencephalograms. Automatic Control: These days, many gadgets are available that can perform their tasks automatically. These devices contain various components…

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