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Increase microcontroller code efficiency
2008-03-09 13:36:00 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 [?] More About: Microcontroller , Code , Efficiency
Minimizing microcontroller code size
2008-03-09 13:36:00 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 [?] More About: Microcontroller , Code , Size
Building embedded software using algorithm flow charts
2008-03-09 13:35:00 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. [?] More About: Software , Building , Charts , Embedded Software
Microcontroller eats too much of RAM
2008-03-09 13:35:00 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 [?] More About: Microcontroller
Programming microcontrollers AduC70xx using boot-loader and ARMWSD utility
2008-03-09 13:34:00 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 [?] More About: Programming , Utility , Microcontrollers , Boot , Loader
ARM Development Tools
2008-03-09 13:34:00 http://www.arm.com/ Professional information about ARM microcontrollers;http://www.codesourcery. com/gnu_toolchains/arm.html develops improvements to the GNU Tool-chain for ARM processors and provides regular, carefully tested, pre-compiled releases of the GNU Tool-chain;http://www.EmbeddedArtists.com / Ships pre-setup GCC build environment with all their Quick-Start Boards/Kits;http://www.embedinfo.com/ Embest IDE for ARM, include Compiler,debugger,editor,project manager,flash programmer,JTAG Emulator, Low cost;http://www.iar.com/ Embedded Workbench for ARM7,9,11 C/C++ compiler;http://www.keil.com/ IDE,Debugger,Simulator which [?] More About: Tools , Development
New ARM7 Microcontrollers from NXP with LCD support
2008-03-09 13:33:00 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 [?] More About: Support , Microcontrollers
32 bit microcontrollers from ATMEL with ARM7 core
2008-03-09 13:31:00 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 [?] More About: Microcontrollers
Data
2008-02-15 08:22:00 Atomic masses shown in parentheses indicate the most stable isotope (longest half-life) known. Electron configuration data was taken from Douglas C. Giancoli's Physics, 3rd edition. Average atomic masses were taken from Kenneth W. Whitten's, Kenneth D. Gailey's, and Raymond E. Davis' General Chemistry, 3rd edition. In the latter book, the masses were specified as 1985 IUPAC values. More About: Data
Table (portrait view)
2008-02-15 08:21:00 Periodic table of chemical elements. More About: View , Table , Portrait
Table (landscape view)
2008-02-15 08:20:00 Periodic table of chemical elements. More About: Landscape , View , Table
Switches, process actuated
2008-02-15 08:12:00 It is very important to keep in mind that the "normal" contact status of a process-actuated switch refers to its status when the process is absent and/or inactive, not "normal" in the sense of process conditions as expected during routine operation. For instance, a normally-closed low-flow detection switch installed on a coolant pipe will be maintained in the actuated state (open) when there is regular coolant flow through the pipe. If the coolant flow stops, the flow switch will go to its "normal" (unactuated) status of closed. A limit switch is one actuated by contact with a moving machine part. An electronic limit switch senses mechanical motion, but does so using light, magnetic fields, or other non-contact means. More About: Process , Switches
Wires and connections
2008-02-15 08:06:00 Older electrical schematics showed connecting wires crossing, while non-connecting wires "jumped" over each other with little half-circle marks. Newer electrical schematics show connecting wires joining with a dot, while non-connecting wires cross with no dot. However, some people still use the older convention of connecting wires crossing with no dot, which may create confusion. For this reason, I opt to use a hybrid convention, with connecting wires unambiguously connected by a dot, and non-connecting wires unambiguously "jumping" over one another with a half-circle mark. While this may be frowned upon by some, it leaves no room for interpretational error: in each case, the intent is clear and unmistakable: More About: Connections
Potential pitfalls
2008-02-15 08:06:00 Fallacious reasoning and poor interpersonal relations account for more failed or belabored troubleshooting efforts than any other impediments. With this in mind, the aspiring troubleshooter needs to be familiar with a few common troubleshooting mistakes. Trusting that a brand-new component will always be good. While it is generally true that a new component will be in good condition, it is not always true. It is also possible that a component has been mis-labeled and may have the wrong value (usually this mis-labeling is a mistake made at the point of distribution or warehousing and not at the manufacturer, but again, not always!). Not periodically checking your test equipment. This is especially true with battery-powered meters, as weak batteries may give spurious readings. When using meters to safety-check for dangerous voltage, remember to test the meter on a known source of voltage both before and after checking the circuit to be serviced, to make sure the meter is in p...
Likely failures in unproven systems
2008-02-15 08:05:00 "All men are liable to error;" John Locke Whereas the last section deals with component failures in systems that have been successfully operating for some time, this section concentrates on the problems plaguing brand-new systems. In this case, failure modes are generally not of the aging kind, but are related to mistakes in design and assembly caused by human beings. Wiring problems In this case, bad connections are usually due to assembly error, such as connection to the wrong point or poor connector fabrication. Shorted failures are also seen, but usually involve misconnections (conductors inadvertently attached to grounding points) or wires pinched under box covers. Another wiring-related problem seen in new systems is that of electrostatic or electromagnetic interference between different circuits by way of close wiring proximity. This kind of problem is easily created by routing sets of wires too close to each other (especially routing signal cables close to po... More About: Systems
Likely failures in proven systems
2008-02-15 08:04:00 The following problems are arranged in order from most likely to least likely, top to bottom. This order has been determined largely from personal experience troubleshooting electrical and electronic problems in automotive, industry, and home applications. This order also assumes a circuit or system that has been proven to function as designed and has failed after substantial operation time. Problems experienced in newly assembled circuits and systems do not necessarily exhibit the same probabilities of occurrence. Operator error A frequent cause of system failure is error on the part of those human beings operating it. This cause of trouble is placed at the top of the list, but of course the actual likelihood depends largely on the particular individuals responsible for operation. When operator error is the cause of a failure, it is unlikely that it will be admitted prior to investigation. I do not mean to suggest that operators are incompetent and irresponsible -- quite the c... More About: Systems , Proven
Microprocessors
2008-01-10 08:29:00 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 essentially the same thing, except with greater capability. A helpful illustration is that of early automatic machine tool control technology. Called open-loop, or sometimes just NC (numerical co...
Microprocessor programming
2008-01-10 08:29:00 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 machine language. While machine language software can be "worded" in binary notation, it is often written in hexadecimal form, because it is easier for human beings to work with. For example, I'... More About: Programming
Finite-state machines
2008-01-10 08:28:00 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, these new dynamics find useful application, while other times they are merely interesting. With look-up tables programmed into memory devices, feedback from the data outputs back to the address i... More About: Machines , State
Look-up tables
2008-01-10 08:27:00 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 functionality of a half adder: If this ROM has been written with the above data (representing a half-adder's truth table), driving the A and B address inputs will cause the respective memor... More About: Tables
A binary adder
2008-01-10 08:27:00 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 ? 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 will only perform one function: add two binary bits together. To make them do something else would take re-wiring, and perhaps different componentry. In this sense, digital arithmetic circuits ...
Memory with moving parts: "Drives"
2008-01-10 08:26:00 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 paper, mylar material is often used, with optical reading of the tape being the most popular method. Magnetic tape (very similar to audio or video cassette tape) was the next logical improvement i... More About: Memory , Moving , Parts
Read-only memory
2008-01-10 08:25:00 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. Such a device is given a rather oxymoronic name: the EPROM (Erasable Programmable Read-Only Memory). EPROMs come in two basic varieties: Electrically-erasable (EEPROM) and Ultraviolet-erasable (U... More About: Read
Historical, nonmechanical memory technologies
2008-01-10 08:25:00 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 each end, one to create sound waves from electrical impulses, and the other to generate electrical impulses from sound waves. A stream of serial binary data was sent to the transmitting transducer as... More About: Memory , Technologies , Historical
Digital memory terms and concepts
2008-01-10 08:24:00 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 later in this lesson). With other types of devices, data is addressed in terms of an actual physical location on the surface of some type of media (the tracks and sectors of circular computer disks, fo... More About: Memory , Concepts , Terms , Digital
Modern nonmechanical memory
More articles from this author:2008-01-10 08:24:00 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 of storage (and we probably do), we'll have to have many latches arranged in some kind of an array where we can selectively address which one (or which set) we're reading from or writing to. Usin... More About: Memory , Modern 1, 2 |
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