Owner: born4electronics1 URL:http://www.born4electronics1.blogspot.com/ Join Date: Sun, 09 Mar 2008 12:26:41 -0500 Rating:0 Site Description: complete guide for electronics students
complete guide for electronics students
complete guide for electronics students
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Increase microcontroller code efficiency 2008-03-09 07:36:53 C compilers are getting more and more advanced, but there is always a trade off made between speed and code size. Compiled code can be faster or smaller but not both. So you have to choose which part is more important speed or code size.The Increase of microcontroller code efficiency can be done in many […]
Minimizing microcontroller code size 2008-03-09 07:36:29 Reducing microcontroller code size isn’t ease task, but what if you want resulting code to fit your available memory…Minimizing microcontroller code size can be done in two ways:Firs is using compilers optimization feature by code size. This optimization is very dangerous. Your optimized code may not work as supposed to because compiler may eliminate some […]
Microcontroller eats too much of RAM 2008-03-09 07:36:03 All you know that microcontrollers have limited amount RAM and EEPROM. For instance ATMega128 has 4-Kbytes of RAM, 4-Kbyte of EEPROM. This may seem quite enough for some applications, but more complicated routines require more of RAM. And there is no compiler that can do better optimization on usage of ram than programmer.The main aim […] Read more:Microcontroller
Building embedded software using algorithm flow charts 2008-03-09 07:35:36 Embedded software consists of various functions performing particular tasks. Before writing any ASM or C code it is good to draw algorithm
flow chart. Flow charts are visual method of representing inner algorithm. It is easer analyze the algorithm and write the code according to diagram.The main parts of diagram: Fig 1. Simple series instructions Fig 2. […] Read more:Building
, embedded
ARM Development Tools 2008-03-09 07:35:13 Professional information about ARM microcontrollers; develops improvements to the GNU Tool-chain for ARM processors and provides regular, carefully tested, pre-compiled releases of the GNU Tool-chain; Ships pre-setup GCC build environment with all their Quick-Start Boards/Kits; Embest IDE for ARM, include Compiler,debugger,editor,project manager,flash programmer,JTAG Emulator, Low cost; Embedded Workbench for ARM7,9,11 C/C++ compiler; IDE,Debugger,Simulator which […] Read more:Development
, Tools
Programming microcontrollers AduC70xx using boot-loader and ARMWSD utility 2008-03-09 07:34:43 Firmware for AduC70xx ARM microcontrollers can be uploaded using built in boot-loader. To work with boot-loader Analog Devices offer to use small free program ARMWSD working under windows system. Program doesn’t require installation. ARMWSD communicates with AduC70xx via COM-port. Simple programming steps looks like this: Connect target board to PC COM port; Go to Configure->Parts and select […] Read more:Programming
New ARM7 Microcontrollers from NXP with LCD support 2008-03-09 07:34:18 New microcontroller LPC2478 from NXP company is based on ARM7 core with built in Flash memory and have built in LCD interface. LPC2470 has no Flash memory.LPC24 series have two high speed buses AHB to ensure independent work of peripherals like LCD, 10/100 Ethernet, USB and two channels of CAN. LPC24xx have reasonable low prices […]
32 bit microcontrollers from ATMEL with ARM7 core 2008-03-09 07:33:48 Somehow I’ve been sticked to NXP LPC2xxx series microcontrollers and left other brands behind. There are many major manufacturers of ARM microcontrollers. One of them that is worth to pay attention is Atmel with its AT91SAM7 (Smart ARM7) series. SAM7 series of microcontrollers have built in Flash memory and data memory as well. Core is […]
Microprocessor programming 2008-01-10 01:30:08 The "vocabulary" of instructions which any particular microprocessor chip possesses is specific to that model of chip. An Intel 80386, for example, uses a completely different set of binary codes than a Motorola 68020, for designating equivalent functions. Unfortunately, there are no standards in place for microprocessor instructions. This makes programming at the very lowest level very confusing and specialized. When a human programmer develops a set of instructions to directly tell a microprocessor how to do something (like automatically control the fuel injection rate to an engine), they're programming in the CPU's own "language." This language, which consists of the very same binary codes which the Control Unit inside the CPU chip decodes to perform tasks, is often referred to as Read more:Microprocessor
Microprocessors 2008-01-10 01:29:34 Early computer science pioneers such as Alan Turing and John Von Neumann postulated that for a computing device to be really useful, it not only had to be able to generate specific outputs as dictated by programmed instructions, but it also had to be able to write data to memory, and be able to act on that data later. Both the program steps and the processed data were to reside in a common memory "pool," thus giving way to the label of the stored-program computer. Turing's theoretical machine utilized a sequential-access tape, which would store data for a control circuit to read, the control circuit re-writing data to the tape and/or moving the tape to a new position to read more data. Modern computers use random-access memory devices instead of sequential-access tapes to accomplish essen
Finite-state machines 2008-01-10 01:29:05 Feedback is a fascinating engineering principle. It can turn a rather simple device or process into something substantially more complex. We've seen the effects of feedback intentionally integrated into circuit designs with some rather astounding effects: Comparator + negative feedback -----------> controllable-gain amplifierComparator + positive feedback -----------> comparator with hysteresisCombinational logic + positive feedback --> multivibrator In the field of process instrumentation, feedback is used to transform a simple measurement system into something capable of control: Measurement system + negative feedback ---> closed-loop control system Feedback, both positive and negative, has the tendency to add whole new dynamics to the operation of a device or system. Sometimes Read more:machines
Look-up tables 2008-01-10 01:28:30 Having learned about digital memory devices in the last chapter, we know that it is possible to store binary data within solid-state devices. Those storage "cells" within solid-state memory devices are easily addressed by driving the "address" lines of the device with the proper binary value(s). Suppose we had a ROM memory circuit written, or programmed, with certain data, such that the address lines of the ROM served as inputs and the data lines of the ROM served as outputs, generating the characteristic response of a particular logic function. Theoretically, we could program this ROM chip to emulate whatever logic function we wanted without having to alter any wire connections or gates. Consider the following example of a 4 x 2 bit ROM memory (a very small memory!) programmed with the
A binary adder 2008-01-10 01:27:40 Suppose we wanted to build a device that could add two binary bits together. Such a device is known as a half-adder, and its gate circuit looks like this: The Σ symbol represents the "sum" output of the half-adder, the sum's least significant bit (LSB). Cout represents the "carry" output of the half-adder, the sum's most significant bit (MSB). If we were to implement this same function in ladder (relay) logic, it would look like this: Either circuit is capable of adding two binary digits together. The mathematical "rules" of how to add bits together are intrinsic to the hard-wired logic of the circuits. If we wanted to perform a different arithmetic operation with binary bits, such as multiplication, we would have to construct another circuit. The above circuit designs
Memory with moving parts: "Drives" 2008-01-10 01:27:00 The earliest forms of digital data storage involving moving parts was that of the punched paper card. Joseph Marie Jacquard invented a weaving loom in 1780 which automatically followed weaving instructions set by carefully placed holes in paper cards. This same technology was adapted to electronic computers in the 1950's, with the cards being read mechanically (metal-to-metal contact through the holes), pneumatically (air blown through the holes, the presence of a hole sensed by air nozzle backpressure), or optically (light shining through the holes). An improvement over paper cards is the paper tape, still used in some industrial environments (notably the CNC machine tool industry), where data storage and speed demands are low and ruggedness is highly valued. Instead of wood-fiber pa Read more:Memory
Read-only memory 2008-01-10 01:26:25 Read-only memory (ROM) is similar in design to static or dynamic RAM circuits, except that the "latching" mechanism is made for one-time (or limited) operation. The simplest type of ROM is that which uses tiny "fuses" which can be selectively blown or left alone to represent the two binary states. Obviously, once one of the little fuses is blown, it cannot be made whole again, so the writing of such ROM circuits is one-time only. Because it can be written (programmed) once, these circuits are sometimes referred to as PROMs (Programmable Read-Only Memory). However, not all writing methods are as permanent as blown fuses. If a transistor latch can be made which is resettable only with significant effort, a memory device that's something of a cross between a RAM and a ROM can be built
Historical, nonmechanical memory technologies 2008-01-10 01:25:53 Perhaps the most ingenious technique was that of the delay line. A delay line is any kind of device which delays the propagation of a pulse or wave signal. If you've ever heard a sound echo back and forth through a canyon or cave, you've experienced an audio delay line: the noise wave travels at the speed of sound, bouncing off of walls and reversing direction of travel. The delay line "stores" data on a very temporary basis if the signal is not strengthened periodically, but the very fact that it stores data at all is a phenomenon exploitable for memory technology. Early computer delay lines used long tubes filled with liquid mercury, which was used as the physical medium through which sound waves traveled along the length of the tube. An electrical/sound transducer was mounted at eac Read more:Historical
, technologies
Modern nonmechanical memory 2008-01-10 01:25:18 Now we can proceed to studying specific types of digital storage devices. To start, I want to explore some of the technologies which do not require any moving parts. These are not necessarily the newest technologies, as one might suspect, although they will most likely replace moving-part technologies in the future. A very simple type of electronic memory is the bistable multivibrator. Capable of storing a single bit of data, it is volatile (requiring power to maintain its memory) and very fast. The D-latch is probably the simplest implementation of a bistable multivibrator for memory usage, the D input serving as the data "write" input, the Q output serving as the "read" output, and the enable input serving as the read/write control line: If we desire more than one bit's worth Read more:Modern
Digital memory terms and concepts 2008-01-10 01:24:46 When we store information in some kind of circuit or device, we not only need some way to store and retrieve it, but also to locate precisely where in the device that it is. Most, if not all, memory devices can be thought of as a series of mail boxes, folders in a file cabinet, or some other metaphor where information can be located in a variety of places. When we refer to the actual information being stored in the memory device, we usually refer to it as the data. The location of this data within the storage device is typically called the address, in a manner reminiscent of the postal service. With some types of memory devices, the address in which certain data is stored can be called up by means of parallel data lines in a digital circuit (we'll discuss this in more detail late Read more:Digital
Introduction to DIGITAL STORAGE (MEMORY) Why digital 2008-01-10 01:24:16 Although many textbooks provide good introductions to digital memory technology, I intend to make this chapter unique in presenting both past and present technologies to some degree of detail. While many of these memory designs are obsolete, their foundational principles are still quite interesting and educational, and may even find re-application in the memory technologies of the future. The basic goal of digital memory is to provide a means to store and access binary data: sequences of 1's and 0's. The digital storage of information holds advantages over analog techniques much the same as digital communication of information holds advantages over analog communication. This is not to say that digital data storage is unequivocally superior to analog, but it does address some of the more Read more:Introduction
Network protocols 2008-01-10 01:23:18 Aside from the issues of the physical network (signal types and voltage levels, connector pinouts, cabling, topology, etc.), there needs to be a standardized way in which communication is arbitrated between multiple nodes in a network, even if it's as simple as a two-node, point-to-point system. When a node "talks" on the network, it is generating a signal on the network wiring, be it high and low DC voltage levels, some kind of modulated AC carrier wave signal, or even pulses of light in a fiber. Nodes that "listen" are simply measuring that applied signal on the network (from the transmitting node) and passively monitoring it. If two or more nodes "talk" at the same time, however, their output signals may clash (imagine two logic gates trying to apply opposite signal voltages to a singl
Network topology 2008-01-10 01:22:39 If we want to connect two digital devices with a network, we would have a kind of network known as "point-to-point:" For the sake of simplicity, the network wiring is symbolized as a single line between the two devices. In actuality, it may be a twisted pair of wires, a coaxial cable, an optical fiber, or even a seven-conductor BogusBus. Right now, we're merely focusing on the "shape" of the network, technically known as its topology. If we want to include more devices (sometimes called nodes) on this network, we have several options of network configuration to choose from: Many network standards dictate the type of topology which is used, while others are more versatile. Ethernet, for example, is commonly implemented in a "bus" topolo
Optical data communication 2008-01-10 01:22:11 A modern alternative to sending (binary) digital information via electric voltage signals is to use optical (light) signals. Electrical signals from digital circuits (high/low voltages) may be converted into discrete optical signals (light or no light) with LEDs or solid-state lasers. Likewise, light signals can be translated back into electrical form through the use of photodiodes or phototransistors for introduction into the inputs of gate circuits. Transmitting digital information in optical form may be done in open air, simply by aiming a laser at a photodetector at a remote distance, but interference with the beam in the form of temperature inversion layers, dust, rain, fog, and other obstructions can present significant engineering problems: One way to avoid the pr Read more:Optical
, communication
Electrical signal types 2008-01-10 01:21:40 With BogusBus, our signal
s were very simple and straightforward: each signal wire (1 through 5) carried a single bit of digital data, 0 Volts representing "off" and 24 Volts DC representing "on." Because all the bits arrived at their destination simultaneously, we would call BogusBus a parallel network technology. If we were to improve the performance of BogusBus by adding binary encoding (to the transmitter end) and decoding (to the receiver end), so that more steps of resolution were available with fewer wires, it would still be a parallel network. If, however, we were to add a parallel-to-serial converter at the transmitter end and a serial-to-parallel converter at the receiver end, we would have something quite different. It is primarily with the use of serial technology that we a Read more:types
Data flow 2008-01-10 01:21:06 Buses and networks are designed to allow communication to occur between individual devices that are interconnected. The flow of information, or data, between nodes can take a variety of forms: With simplex communication, all data flow is unidirectional: from the designated transmitter to the designated receiver. BogusBus is an example of simplex communication, where the transmitter sent information to the remote monitoring location, but no information is ever sent back to the water tank. If all we want to do is send information one-way, then simplex is just fine. Most applications, however, demand more: With duplex communication, the flow of information is bidirectional for each device. Duplex can be further divided into two sub-categories: Half-duplex communic
Networks and busses 2008-01-10 01:20:36 This collection of wires that I keep referring to between the tank and the monitoring location can be called a bus or a network. The distinction between these two terms is more semantic than technical, and the two may be used interchangeably for all practical purposes. In my experience, the term "bus" is usually used in reference to a set of wires connecting digital components within the enclosure of a computer device, and "network" is for something that is physically more widespread. In recent years, however, the word "bus" has gained popularity in describing networks that specialize in interconnecting discrete instrumentation sensors over long distances ("Fieldbus" and "Profibus" are two examples). In either case, we are making reference to the means by which two or more digital devices
Practical considerations of ADC circuits 2008-01-10 01:19:18 Perhaps the most important consideration of an ADC is its resolution. Resolution is the number of binary bits output by the converter. Because ADC circuits take in an analog signal, which is continuously variable, and resolve it into one of many discrete steps, it is important to know how many of these steps there are in total. For example, an ADC with a 10-bit output can represent up to 1024 (210) unique conditions of signal measurement. Over the range of measurement from 0% to 100%, there will be exactly 1024 unique binary numbers output by the converter (from 0000000000 to 1111111111, inclusive). An 11-bit ADC will have twice as many states to its output (2048, or 211), representing twice as many unique conditions of signal measurement between 0% and 100%. Resolution is very impo Read more:Practical
Delta-Sigma () ADC 2008-01-10 01:18:14 One of the more advanced ADC technologies is the so-called delta-sigma, or ΔΣ (using the proper Greek letter notation). In mathematics and physics, the capital Greek letter delta (Δ) represents difference or change, while the capital letter sigma (Σ) represents summation: the adding of multiple terms together. Sometimes this converter is referred to by the same Greek letters in reverse order: sigma-delta, or ΣΔ. In a ΔΣ converter, the analog input voltage signal is connected to the input of an integrator, producing a voltage rate-of-change, or slope, at the output corresponding to input magnitude. This ramping voltage is then compared against ground potential (0 volts) by a comparator. The comparator acts as a sort of 1-bit ADC, producing 1 bit of output ("high" or "low") depen Read more:Delta
, Sigma
Slope (integrating) ADC 2008-01-10 01:17:40 So far, we've only been able to escape the sheer volume of components in the flash converter by using a DAC as part of our ADC circuitry. However, this is not our only option. It is possible to avoid using a DAC if we substitute an analog ramping circuit and a digital counter with precise timing. The is the basic idea behind the so-called single-slope, or integrating ADC. Instead of using a DAC with a ramped output, we use an op-amp circuit called an integrator to generate a sawtooth waveform which is then compared against the analog input by a comparator. The time it takes for the sawtooth waveform to exceed the input signal voltage level is measured by means of a digital counter clocked with a precise-frequency square wave (usually from a crystal oscillator). The basic schematic dia Read more:Slope
Tracking ADC 2008-01-10 01:17:07 A third variation on the counter-DAC-based converter theme is, in my estimation, the most elegant. Instead of a regular "up" counter driving the DAC, this circuit uses an up/down counter. The counter is continuously clocked, and the up/down control line is driven by the output of the comparator. So, when the analog input signal exceeds the DAC output, the counter goes into the "count up" mode. When the DAC output exceeds the analog input, the counter switches into the "count down" mode. Either way, the DAC output always counts in the proper direction to track the input signal. Notice how no shift register is needed to buffer the binary count at the end of a cycle. Since the counter's output continuously tracks the input (rather than counting to meet the input and then resetting ba Read more:Tracking
Successive approximation ADC 2008-01-10 01:16:17 One method of addressing the digital ramp ADC's shortcomings is the so-called successive-approximation ADC. The only change in this design is a very special counter circuit known as a successive-approximation register. Instead of counting up in binary sequence, this register counts by trying all values of bits starting with the most-significant bit and finishing at the least-significant bit. Throughout the count process, the register monitors the comparator's output to see if the binary count is less than or greater than the analog signal input, adjusting the bit values accordingly. The way the register counts is identical to the "trial-and-fit" method of decimal-to-binary conversion, whereby different values of bits are tried from MSB to LSB to get a binary number that equals the origin
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