wireless energy meter data logger on pc

7/28/2019 Wireless Energy Meter Data Logger on Pc

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INTRODUCTION

In this project we show that ho we monitor the energy meter wirelessly. By

using this technique it is very easy to check the pulse to pulse. When we are

monitoring pulse to pulse then we easily detect the maximum load period,

easily check the meter failure and at the same time we easily monitor the

tapping also.

Logic behind this project is to transfer the pulse of meter via radio frequency

module. With the help of radio frequency module we made connectivity

between meter and central monitor system. In this project we check the pulse

monitoring of two meter at a time.

In this project we use three circuits. One each for the meter and one as a

central receiver and transfer the data on the led.

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Transmitter circuit.

In the transmitter circuit we use one small energy meter to get the data of

pulse . Now first of all we connect a load with the meter. In this section of

the project we use one step down transformer to step down the voltage from

220 volt ac to 9-0-9 ac. This transformer is a centre tap transformer having a

current rating of 1 ampere. Output of the centre tap transformer is connected

to the rectifier circuit. In this project we use full wave rectifier to convert the

ac voltage from the transformer to pulsating dc. This pulsating dc is further

converted into smooth dc with the help of capacitor filter. Capacitor convert

the pulsating dc into smooth dc and with the help of

regulator we regulate the voltage to 5 volt dc.

Here we use 7805 regulator to regulate the voltage

for 5 volt dc.

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Figure 1

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Output from the meter is connected to the electronics transmitter circuit via

optocoupler device. Optocoupler device provide an optical isolation

between meter and electronics circuit. In this project we use pc 817

optocoupler. Pin no 1,2 is connected to meter internally and output of the

optocoupler is connected to the lm358 comparator. Other pin of the

comparator is connected to the variable resistor to set the reference voltage.

As the pulse is on the op-amp then circuit provide a output signal. Meter

provides a 3200 pulse for one unit. These 3200 pulses are transmit by the

RF transmitter serially. Here we use 433 MHz transmitters to transmit the

pulse. We connect a 4 bit encoder between pulse and RF transmitter. We use

HT 12 e encoder to interface the data with RF module HT12 E and HT 12 D

decoder are easily available in the market.

The 212 encoders are a series of CMOS LSIs for remote

control system applications. They are capable of encoding

information which consists of N address bits and 12_N data

bits. Each address/data input can be set to one of the two

logic states. The programmed addresses/ data are

transmitted together with the header bits via an RF or an

infrared transmission medium upon receipt of a trigger

signal. The capability to select a TE trigger on the HT12E or a

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DATA trigger on the HT12A further enhances the application

flexibility of the 212 series of encoders. The HT12A

additionally provides a 38 kHz carrier for infrared systems.

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In this portion of transmitter circuit we add a small IC 555 here. Here IC

555 work as a astable multivibrator to produce a square wave when required.

We use this circuit to check the transmitter for proper working. In actual

meter pulse is not very fast, its according to the load. With the help of IC

555 we generate a artificial pulse for fast pulse. One switch is connected

between artificial pulse and actual pulse . We select the switch position as

we required.

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Figure 4


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In the receiver circuit we use two decoder to get the data. Data is received by

the Rf receiver. This rf module is pair version of the transmitter . Rf

receiver demodulate the data and connected to the decoder circuit. In the

decoder circuit we decode the data with address matching. IN the portion of

project we use two decoder circuit because we use two transmitter with two

different energy meter. In both the encoder and decoder circuit we use

separate address line for easy decoding. This address coding point is very

much important in the project. Output of decoder is connected to the 89s51

controller directly. Controller get the input from decoder and converted into

ASCII code and display the same on the lcd display. Here we use 2 by 16

lcd to display the code with specific address and store the data in ram. In

later on this data is to be store on the external memory 24c02.

Controller not only display the data on lcd but at the same time transfer the

data to pc via max 232 ic.

Microcontroller convert the data into serially and transfer to the pc at the rate

of 9600 bps. 9600 is the default baud rate of the pc for interface. In the pc

we display the same data on HyperTerminal or in visual basic platform

In this project we use one 5 volt regulated power supply to

convert the 220 volt ac in to 5 volt dc with the help of the 5 volt

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regulator circuit. First OF all we step down the 220 volt ac into 6 volt

ac with the help of step down transformer. Step down transformer

step down the voltage from 220 volt ac to 9 volt ac. This ac is further

converted into the dc voltage with the help of the full wave rectifier

circuit

Output of the diode is pulsating dc . so to convert the pulsating dc into

smooth dc we use electrolytic capacitor. Electrolytic capacitor convert

the pulsating dc into smooth dc. This Dc is further regulated by the ic

7805 regulator. IC 7805 regulator provide a regulated 5 volt dc to the

microcontroller circuit and lcd circuit.

Pin no 40 of the controller is connected to the positive supply. Pin no

20 is connected to the ground. Pin no 9 is connected to external

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resistor capacitor to provide a automatic reset option when power is

on.

Reset Circuitry:

Pin no 9 of the controller is connected to the reset circuit. On the

circuit we connect one resistor and capacitor circuit to provide a reset

option when power is on

As soon as you give the power supply the 8051 doesnt start. You

need to restart for the microcontroller to start. Restarting the

microcontroller is nothing but giving a Logic 1 to the reset pin at least

for the 2 clock pulses. So it is good to go for a small circuit which can

provide the 2 clock pulses as soon as the microcontroller is powered.

This is not a big circuit we are just using a capacitor to charge the

microcontroller and again discharging via resistor.

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Crystals

Pin no 18 and 19 is connected to external crystal oscillator to provide

a clock to the circuit.

Crystals provide the synchronization of the internal function and to the

peripherals. Whenever ever we are using crystals we need to put the capacitor

behind it to make it free from noises. It is good to go for a 33pf capacitor.

We can also resonators instead of costly crystal which are low cost

and external capacitor can be avoided.

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But the frequency of the resonators varies a lot. And it is strictly not

advised when used for communications projects.

How is this time then calculated?

The speed with which a microcontroller executes instructions is

determined by what is known as the crystal speed. A crystal is a

component connected externally to the microcontroller. The crystal

has different values, and some of the used values are 6MHZ, 10MHZ,

and 11.059 MHz etc.

Thus a 10MHZ crystal would pulse at the rate of 10,000,000 times

per second.

The time is calculated using the formula

No of cycles per second = Crystal frequency in HZ / 12.

For a 10MHZ crystal the number of cycles would be,

10,000,000/12=833333.33333 cycles.

This means that in one second, the microcontroller would execute

833333.33333 cycles.

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Pin no 1 to pin no 8 is PORT 1 and Pin no 10 to 17 is PORT 3. Pin no

18 and 19 of the ic is connected to the external crystal to provide a

external clock to run the internal CPU of controller . Pin no 20 is

ground pin. Pin no 21 to 28 is PORT 2 pins. Pin no 29,30,31 is not

use in this project. We use these pin when we require a extra

memory for the project. If we internal memory of the 89s51 ( which is

4k rom) then we connect pin no 31 to the positive supply.

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The TWS-434 and RWS-434 are extremely small, and are excellentfor applications requiring short-range RF remote controls. Thetransmitter module is only 1/3 the size of a standard postage stamp,and can easily be placed inside a small plastic enclosure.

TWS-434: The transmitter output is up to 8mW at 433.92MHz with a

range of approximately 400 foot (open area) outdoors. Indoors, therange is approximately 200 foot, and will go through most walls.....

TWS-434A

The TWS-434 transmitter accepts both linear and digital inputs, canoperate from 1.5 to 12 Volts-DC, and makes building a miniature

hand-held RF transmitter very easy. The TWS-434 is approximatelythe size of a standard postage stamp.

TWS-434 Pin Diagram

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Sample Transmitter Application Circuit

RWS-434: The receiver also operates at 433.92MHz, and has asensitivity of 3uV. The RWS-434 receiver operates from 4.5 to 5.5volts-DC, and has both linear and digital outputs.

Click on picture for larger image

RWS-434 Receiver

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RWS-434 Pin Diagram

Sample Receiver Application Circuit

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The example above shows the receiver section using the HT-12D decoder IC

for a 4-bit RF remote control system. The transmitter and receiver can also use

the Holtek 8-bit HT-640/HT-648L remote control encoder/decoder combination

for an 8-bit RF remote control system. Here are the schematics for an 8-bit RF

remote control system:

LIQUID CRYSTAL DISPLAY

A liquid crystal display (LCD) is a thin, flat display device made up of anynumber of color ormonochromepixels arrayed in front of a light source or

reflector. It is prized by engineers because it uses very small amounts of

electric power, and is therefore suitable for use in battery-powered electronicdevices.

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Reflective twisted nematic liquid crystal display.

1. Vertical filter film topolarize the light as it enters.2. Glass substrate with ITO electrodes. The shapes of these electrodes

will determine the dark shapes that will appear when the LCD isturned on or off. Vertical ridges etched on the surface are smooth.3. Twisted nematic liquid crystals.4. Glass substrate with common electrode film (ITO) with horizontal

ridges to line up with the horizontal filter.5. Horizontal filter film to block/allow through light.6. Reflective surface to send light back to viewer.

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A subpixel of a color LCD

Overview

Eachpixel of an LCD consists of a layer of liquid crystal molecules alignedbetween two transparent electrodes, and twopolarizing filters, the axes ofpolarity of which are perpendicular to each other. With no liquid crystalbetween the polarizing filters, light passing through one filter would beblocked by the other.

The surfaces of the electrodes that are in contact with the liquid crystalmaterial are treated so as to align the liquid crystal molecules in a particular

direction. This treatment typically consists of a thin polymer layer that isunidirectionally rubbed using a cloth (the direction of the liquid crystalalignment is defined by the direction of rubbing).

Before applying an electric field, the orientation of the liquid crystalmolecules is determined by the alignment at the surfaces. In a twistednematic device (the most common liquid crystal device), the surface

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alignment directions at the two electrodes are perpendicular, and so themolecules arrange themselves in a helical structure, or twist. Because theliquid crystal material is birefringent (i.e. light of different polarizationstravels at different speeds through the material), light passing through one

polarizing filter is rotated by the liquid crystal helix as it passes through theliquid crystal layer, allowing it to pass through the second polarized filter.Half of the light is absorbed by the first polarizing filter, but otherwise theentire assembly is transparent.

When a voltage is applied across the electrodes, a torque acts to align theliquid crystal molecules parallel to the electric field, distorting the helicalstructure (this is resisted by elastic forces since the molecules areconstrained at the surfaces). This reduces the rotation of the polarization ofthe incident light, and the device appears gray. If the applied voltage is large

enough, the liquid crystal molecules are completely untwisted and thepolarization of the incident light is not rotated at all as it passes through theliquid crystal layer. This light will then be polarized perpendicular to thesecond filter, and thus be completely blocked and the pixel will appear

black. By controlling the voltage applied across the liquid crystal layer ineachpixel, light can be allowed to pass through in varying amounts,correspondingly illuminating the pixel.

With a twisted nematic liquid crystal device it is usual to operate the devicebetween crossed polarizers, such that it appears bright with no applied

voltage. With this setup, the dark voltage-on state is uniform. The device canbe operated between parallel polarizers, in which case the bright and darkstates are reversed (in this configuration, the dark state appears blotchy).

Both the liquid crystal material and the alignment layer material containionic compounds. If an electric field of one particular polarity is applied fora long period of time, this ionic material is attracted to the surfaces anddegrades the device performance. This is avoided by applying either analternating current, or by reversing the polarity of the electric field as the

device is addressed (the response of the liquid crystal layer is identical,regardless of the polarity of the applied field).

When a large number of pixels is required in a display, it is not feasible todrive each directly since then each pixel would require independentelectrodes. Instead, the display is multiplexed. In a multiplexed display,electrodes on one side of the display are grouped and wired together

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(typically in columns), and each group gets its own voltage source. On theother side, the electrodes are also grouped (typically in rows), with eachgroup getting a voltage sink. The groups are designed so each pixel has aunique, unshared combination of source and sink. The electronics, or thesoftware driving the electronics then turns on sinks in sequence, and drivessources for the pixels of each sink.

Important factors to consider when evaluating an LCD monitor includeresolution, viewable size, response time (sync rate), matrix type (passive oractive), viewing angle, color support, brightness and contrast ratio, aspectratio, and input ports (e.g. DVI orVGA).

Color displays

In color LCDs each individualpixel is divided into three cells, or subpixels,which are colored red, green, and blue, respectively, by additional filters(pigment filters, dye filters and metal oxide filters). Each subpixel can becontrolled independently to yield thousands or millions of possible colors for

each pixel. OlderCRT monitors employ a similar method.

Color components may be arrayed in variouspixel geometries, depending onthe monitor's usage. If software knows which type of geometry is being usedin a given LCD, this can be used to increase the apparent resolution of themonitor through subpixel rendering. This technique is especially useful fortext anti-aliasing.

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Passive-matrix and active-matrix

A general purpose alphanumeric LCD, with two lines of 16 characters.

LCDs with a small number of segments, such as those used in digitalwatches andpocket calculators, have a single electrical contact for eachsegment. An external dedicated circuit supplies an electric charge to controleach segment. This display structure is unwieldy for more than a few display

elements.

Small monochrome displays such as those found in personal organizers, orolderlaptop screens have a passive-matrix structure employing supertwistnematic (STN) or double-layer STN (DSTN) technology (DSTN corrects acolor-shifting problem with STN). Each row or column of the display has asingle electrical circuit. The pixels are addressed one at a time by row andcolumn addresses. This type of display is called a passive matrix because the

pixel must retain its state between refreshes without the benefit of a steady

electrical charge. As the number of pixels (and, correspondingly, columnsand rows) increases, this type of display becomes less feasible. Very slowresponse times and poorcontrast are typical of passive-matrix LCDs.

High-resolution color displays such as modern LCD computer monitors andtelevisions use an active matrix structure. A matrix ofthin-film transistors(TFTs) is added to the polarizing and color filters. Each pixel has its own

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dedicated transistor, allowing each column line to access one pixel. When arow line is activated, all of the column lines are connected to a row of pixelsand the correct voltage is driven onto all of the column lines. The row line isthen deactivated and the next row line is activated. All of the row lines areactivated in sequence during a refresh operation. Active-matrix displays aremuch brighter and sharper than passive-matrix displays of the same size, andgenerally have quicker response times, producing much better images.

Twisted nematic (TN)

LCD Display Technology

.In-plane switching (IPS)

control

Some LCD panels have defective transistors, causing permanently lit or unlitpixels which are commonly referred to as stuck pixels ordead pixelsrespectively. Unlike integrated circuits, LCD panels with a few defective

pixels are usually still usable. It is also economically prohibitive to discard apanel with just a few defective pixels because LCD panels are much largerthan ICs. Manufacturers have different standards for determining amaximum acceptable number of defective pixels. The maximum acceptable

number of defective pixels for LCD varies a lot (such as zero-tolerancepolicy and 11-dead-pixel policy) from one brand to another, often a hotdebate between manufacturers and customers. To regulate the acceptabilityof defects and to protect the end user, ISO released the ISO 13406-2standard. However, not every LCD manufacturer conforms to the ISOstandard and the ISO standard is quite often interpreted in different ways.

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Examples of defects in LCD displays

LCD panels are more likely to have defects than most ICs due to their largersize. In this example, a 12" SVGA LCD has 8 defects and a 6" wafer hasonly 3 defects. However, 134 of the 137 dies on the wafer will beacceptable, whereas rejection of the LCD panel would be a 0% yield. Thestandard is much higher now due to fierce competition betweenmanufacturers and improved quality control. An SVGA LCD panel with 4defective pixels is usually considered defective and customers can request anexchange for a new one. Some manufacturers, notably in South Korea wheresome of the largest LCD panel manufacturers, such as LG, are located, now

have "zero defective pixel guarantee" and would replace a product even withone defective pixel. Even where such guarantees do not exist, the location ofdefective pixels is important. A display with only a few defective pixels may

be unacceptable if the defective pixels are near each other. Manufacturersmay also relax their replacement criteria when defective pixels are in thecenter of the viewing area.

Zero-power displaysThe zenithal bistable device (ZBD), developed by QinetiQ (formerlyDERA), can retain an image without power. The crystals may exist in one oftwo stable orientations (Black and "White") and power is only required tochange the image. ZBD Displays is a spin-off company from QinetiQ whomanufacture both grayscale and colour ZBD devices.

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A French company, Nemoptic, has developed another zero-power,paper-like LCD technology which has been mass-produced in Taiwan since July2003. This technology is intended for use in low-power mobile applicationssuch as e-books and wearable computers. Zero-power LCDs are incompetition with electronic paper.

Kent Displays has also developed a "no power" display that uses PolymerStabilized Cholesteric Liquid Crystals (ChLCD). The major drawback to theChLCD display is slow refresh rate, especially with low temperatures.

Drawbacks

LCD technology still has a few drawbacks in comparison to some otherdisplay technologies:

While CRTs are capable of displaying multiple video resolutionswithout introducing artifacts, LCD displays produce crisp images only intheir "native resolution" and, sometimes, fractions of that native resolution.Attempting to run LCD display panels at non-native resolutions usuallyresults in the panel scaling the image, which introduces blurriness or"blockiness".

LCD displays have a lowercontrast ratio than that on a plasma displayor CRT. This is due to their "light valve" nature: some light always leaksout and turns black into gray. In brightly lit rooms the contrast of LCDmonitors can, however, exceed some CRT displays due to highermaximum brightness.

LCDs have longer response time than their plasma and CRTcounterparts, older displays creating visible ghosting when images rapidlychange; this drawback, however, is continually improving as thetechnology progresses and is hardly noticeable in current LCD displayswith "overdrive" technology. Most newer LCDs have response times of

around 8 ms. In addition to the response times, some LCD panels have significant

input lag, which makes them unsuitable for fast and time-precise mouseoperations (CAD design, FPS gaming) as compared to CRTs

Overdrive technology on some panels can produce artifacts acrossregions of rapidly transitioning pixels (eg. video images) that looks likeincreased image noise or halos. This is a side effect of the pixels being

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driven past their intended brightness value (or rather the intended voltagenecessary to produce this necessary brightness/colour) and then allowed tofall back to the target brightness in order to enhance response times.

LCD display panels have a limited viewing angle, thus reducing thenumber of people who can conveniently view the same image. As theviewer moves closer to the limit of the viewing angle, the colors andcontrast appear to deteriorate. However, this negative has actually beencapitalized upon in two ways. Some vendors offer screens withintentionally reduced viewing angle, to provide additional privacy, such aswhen someone is using a laptop in a public place. Such a set can also showtwo different images to one viewer, providing a three-dimensional effect.

Some users of older (around pre-2000) LCD monitors complain ofmigraines and eyestrain problems due to flicker from fluorescent

backlights fed at 50 or 60 Hz. This does not happen with most modern

displays which feed backlights with high-frequency current. LCD screens occasionally suffer from image persistence, which is

similar to screen burn on CRT and plasma displays. This is becoming lessof a problem as technology advances, with newer LCD panels usingvarious methods to reduce the problem. Sometimes the panel can berestored to normal by displaying an all-white pattern for extended periodsof time.

Some light guns do not work with this type of display since they donot have flexible lighting dynamics that CRTs have. However, the fieldemission display will be a potential replacement for LCD flat-paneldisplays since they emulate CRTs in some technological ways.

Some panels are incapable of displaying low resolution screen modes(such as 320x200). However, this is due to the circuitry that drives theLCD rather than the LCD itself.

Consumer LCD monitors are more fragile than their CRTcounterparts, with the screen especially vulnerable. However, lighterweight makes falling less dangerous, and some displays may be protectedwith glass shields.

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8051 micro controller

The 8051

The 8051 developed and launched in the early 80`s, is one of the mostpopular micro controller in use today. It has a reasonably large amount ofbuilt in ROM and RAM. In addition it has the ability to access externalmemory.

The generic term `8x51` is used to define the device. The value of x definingthe kind of ROM, i.e. x=0, indicates none, x=3, indicates mask ROM, x=7,indicates EPROM and x=9 indicates EEPROM or Flash.

A note on ROM

The early 8051, namely the 8031 was designed without any ROM. Thisdevice could run only with external memory connected to it. Subsequentdevelopments lead to the development of the PROM or the programmableROM. This type had the disadvantage of being highly unreliable.

The next in line, was the EPROM or Erasable Programmable ROM. Thesedevices used ultraviolet light erasable memory cells. Thus a program could

be loaded, tested and erased using ultra violet rays. A new program couldthen be loaded again.

An improved EPROM was the EEPROM or the electrically erasable PROM.This does not require ultra violet rays, and memory can be cleared usingcircuits within the chip itself.

Finally there is the FLASH, which is an improvement over the EEPROM.While the terms EEPROM and flash are sometimes used interchangeably,the difference lies in the fact that flash erases the complete memory at onestroke, and not act on the individual cells. This results in reducing the timefor erasure.

Different microcontrollers in market.

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PIC One of the famous microcontrollers used in the industries. It is

based on RISC Architecture which makes the microcontroller process faster thanother microcontroller.

INTEL These are the first to manufacture microcontrollers. These are not

as sophisticated other microcontrollers but still the easiest one to learn.

ATMEL Atmels AVR microcontrollers are one of the most

powerful in the embedded industry. This is the only microcontroller having 1kb ofram even the entry stage. But it is unfortunate that in India we are unable to findthis kind of microcontroller.

Intel 8051

Intel 8051 is CISC architecture which is easy to program in assembly language and alsohas a good support for High level languages.

The memory of the microcontroller can be extended up to 64k.

This microcontroller is one of the easiest microcontrollers to learn.

The 8051 microcontroller is in the field for more than 20 years. There are lots of booksand study materials are readily available for 8051.

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Derivatives

The best thing done by Intel is to give the designs of the 8051 microcontroller toeveryone. So it is not the fact that Intel is the only manufacture for the 8051 there morethan 20 manufactures, with each of minimum 20 models. Literally there are hundreds ofmodels of 8051 microcontroller available in market to choose. Some of the majormanufactures of 8051 are

Atmel

Philips

Philips

The Philipss 8051 derivatives has more number of features than in anymicrocontroller. The costs of the Philips microcontrollers are higher than the Atmelswhich makes us to choose Atmel more often than Philips

Dallas

Dallas has made many revolutions in the semiconductor market. Dallass 8051derivative is the fastest one in the market. It works 3 times as fast as a 8051 can process.But we are unable to get more in India.

Atmel

These people were the one to master the flash devices. They are the cheapest

microcontroller available in the market. Atmels even introduced a 20pin variant of 8051named 2051. The Atmels 8051 derivatives can be got in India less than 70 rupees. Thereare lots of cheap programmers available in India for Atmel. So it is always good forstudents to stick with 8051 when you learn a new microcontroller.

]

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Architecture

Architecture is must to learn because before learning new machine it is necessary to learnthe capabilities of the machine. This is some thing like before learning about the car you

cannot become a good driver. The architecture of the 8051 is given below.

The 8051 doesnt have any special feature than other microcontroller. The only feature isthat it is easy to learn. Architecture makes us to know about the hardware features of themicrocontroller. The features of the 8051 are

4K Bytes of Flash Memory

128 x 8-Bit Internal RAM

Fully Static Operation: 1 MHz to 24 MHz

32 Programmable I/O Lines

Two 16-Bit Timer/Counters

Six Interrupt Sources (5 Vectored)

Programmable Serial Channel

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Low Power Idle and Power Down Modes

The 8051 has a 8-Bit CPU that means it is able to process 8 bit of data at a time. 8051 has235 instructions. Some of the important registers and their functions are

Lets now move on to a practical example. We shall work on a simple

practical application and using the example as a base, shall explore the

various features of the 8051 microcontroller.

Consider an electric circuit as follows,

The positive side (+ve) of the battery is connected to one side of a switch.The other side of the switch is connected to a bulb or LED (Light EmittingDiode). The bulb is then connected to a resistor, and the other end of theresistor is connected to the negative (-ve) side of the battery.

When the switch is closed or switched on the bulb glows. When the switchis open or switched off the bulb goes off

If you are instructed to put the switch on and off every 30 seconds, howwould you do it? Obviously you would keep looking at your watch andevery time the second hand crosses 30 seconds you would keep turning theswitch on and off.

Imagine if you had to do this action consistently for a full day. Do you think

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you would be able to do it? Now if you had to do this for a month, a year??

No way, you would say!

The next step would be, then to make it automatic. This is where we use theMicrocontroller.

But if the action has to take place every 30 seconds, how will themicrocontroller keep track of time?

Execution time

Look at the following instruction,clr p1.0

This is an assembly language instruction. It means we are instructing themicrocontroller to put a value of zero in bit zero of port one. Thisinstruction is equivalent to telling the microcontroller to switch on the bulb.The instruction then to instruct the microcontroller to switch off the bulb is,

Set p1.0

This instructs the microcontroller to put a value of one in bit zero of portone.

Dont worry about what bit zero and port one means. We shall learn it inmore detail as we proceed.

There are a set of well defined instructions, which are used whilecommunicating with the microcontroller. Each of these instructions requiresa standard number of cycles to execute. The cycle could be one or more innumber.

How is this time then calculated?

The speed with which a microcontroller executes instructions is determinedby what is known as the crystal speed. A crystal is a component connectedexternally to the microcontroller. The crystal has different values, and someof the used values are 6MHZ, 10MHZ, and 11.059 MHz etc.

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Thus a 10MHZ crystal would pulse at the rate of 10,000,000 times persecond.

The time is calculated using the formula

No of cycles per second = Crystal frequency in HZ / 12.

For a 10MHZ crystal the number of cycles would be,

10,000,000/12=833333.33333 cycles.

This means that in one second, the microcontroller would execute 833333.33333 cycles.

Therefore for one cycle, what would be the time? Try it out.

The instruction clr p1.0 would use one cycle to execute. Similarly, the instruction setbp1.0 also uses one cycle.

So go ahead and calculate what would be the number of cycles required to be executed toget a time of 30 seconds!

Getting back to our bulb example, all we would need to do is to instruct themicrocontroller to carry out some instructions equivalent to a period of 30 seconds, likecounting from zero upwards, then switch on the bulb, carry out instructions equivalent to30 seconds and switch off the bulb.

Just put the whole thing in a loop, and you have a never ending on-off sequence.

Let us now have a look at the features of the 8051core, keeping the aboveexample as a reference,

1. 8-bit CPU.( Consisting of the A and B registers)

Most of the transactions within the microcontroller are carried out throughthe A register, also known as the Accumulator. In addition all arithmeticfunctions are carried out generally in the A register. There is anotherregister known as the B register, which is used exclusively for

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multiplication and division.

Thus an 8-bit notation would indicate that the maximum value that can beinput into these registers is 11111111. Puzzled?

The value is not decimal 111, 11,111! It represents a binary number, havingan equivalent value of FF in Hexadecimal and a value of 255 in decimal.

We shall read in more detail on the different numbering systems namely theBinary and Hexadecimal system in our next module.

2. 4K on-chip ROM

Once you have written out the instructions for the microcontroller, where do

you put these instructions?

Obviously you would like these instructions to be safe, and not get deletedor changed during execution. Hence you would load it into the ROM

The size of the program you write is bound to vary depending on theapplication, and the number of lines. The 8051 microcontroller gives youspace to load up to 4K of program size into the internal ROM.

4K, thats all? Well just wait. You would be surprised at the amount of stuffyou can load in this 4K of space.

Of course you could always extend the space by connecting to 64K ofexternal ROM if required.

3. 128 bytes on-chip RAM

This is the space provided for executing the program in terms of movingdata, storing data etc.

4. 32 I/O lines. (Four- 8 bit ports, labeled P0, P1, P2, P3)

In our bulb example, we used the notation p1.0. This means bit zero of portone. One bit controls one bulb.

Thus port one would have 8 bits. There are a total of four ports named p0,

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p1, p2, p3, giving a total of 32 lines. These lines can be used both as input oroutput.

5. Two 16 bit timers / counters.

A microcontroller normally executes one instruction at a time. Howevercertain applications would require that some event has to be trackedindependent of the main program.

The manufacturers have provided a solution, by providing two timers. Thesetimers execute in the background independent of the main program. Oncethe required time has been reached, (remember the time calculationsdescribed above?), they can trigger a branch in the main program.

These timers can also be used as counters, so that they can count the numberof events, and on reaching the required count, can cause a branch in the main

program.

6. Full Duplex serial data receiver / transmitter.

The 8051 microcontroller is capable of communicating with external deviceslike the PC etc. Here data is sent in the form of bytes, at predefined speeds,also known as baud rates.

The transmission is serial, in the sense, one bit at a time

7. 5- interrupt sources with two priority levels (Two external and three

internal)

During the discussion on the timers, we had indicated that the timers cantrigger a branch in the main program. However, what would we do in casewe would like the microcontroller to take the branch, and then return back to

the main program, without having to constantly check whether the requiredtime / count has been reached?

This is where the interrupts come into play. These can be set to either thetimers, or to some external events. Whenever the background program hasreached the required criteria in terms of time or count or an external event,the branch is taken, and on completion of the branch, the control returns to

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the main program.

Priority levels indicate which interrupt is more important, and needs to beexecuted first in case two interrupts occur at the same time.

8. On-chip clock oscillator.

This represents the oscillator circuits within the microcontroller. Thus thehardware is reduced to just simply connecting an external crystal, to achievethe required pulsing rate.

PIN FUNCTION OF IC 89C51.

1 Supply pin of this ic is pin no 40. Normally we apply a 5 volt regulated dcpower supply to this pin. For this purpose either we use step downtransformer power supply or we use 9 volt battery with 7805 regulator.

2 Groundpin of this ic is pin no 20. Pin no 20 is normally connected to theground pin ( normally negative point of the power supply.

3 XTAL is connected to the pin no 18 and pin no 19 of this ic. The quartzcrystal oscillator connected to XTAL1 and XTAL2 PIN. These pins also needs

two capacitors of 30 pf value. One side of each capacitor is connected tocrystal and other pis is connected to the ground point. Normally we connect

a 12 MHz or 11.0592 MHz crystal with this ic.. But we use crystal upto 20

MHz to this pins

4 RESETPIN.. Pin no 9 is the reset pin of this ic.. It is an active high pin.On applying a high pulse to this pin, the micro controller will reset and

terminate all activities. This is often referred to as a power on reset. The high

pulse mustbe high for a minimum of 2 machine cycles before it is allowed to go low.

5. PORT0 Port 0 occupies a total of 8 pins. Pin no 32 to pin no 39. It can beused for input or output. We connect all the pins of the port 0 with the pullup

resistor (10 k ohm) externally. This is due to fact that port 0 is an open drain

mode. It is just like a open collector transistor.

6. PORT1. ALL the ports in micrcontroller is 8 bit wide pin no 1 to pin no 8because it is a 8 bit controller. All the main register and sfr all is mainly 8 bitwide. Port 1 is also occupies a 8 pins. But there is no need of pull up resistor

in this port. Upon reset port 1 act as a input port. Upon reset all the ports act

as a input port

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7. PORT2. port 2 also have a 8 pins. It can be used as a input or output.There is no need of any pull up resistor to this pin.

PORT 3. Port3 occupies a totoal 8 pins from pin no 10 to pin no 17. It can

be used as input or output. Port 3 does not require any pull up resistor. Thesame as port 1 and port2. Port 3 is configured as an output port on reset. Port3 has the additional function of providing some important signals such asinterrupts. Port 3 also use for serial communication.

ALE ALE is an output pin and is active high. When connecting an 8031 to externalmemory, port 0 provides both address and data. In other words, the 8031 multiplexes

address and data through port 0 to save pins. The ALE pin is used for demultiplexing theaddress and data by connecting to the ic 74ls373 chip.

PSEN. PSEN stands for program store eneable. In an 8031 based system in which anexternal rom holds the program code, this pin is connected to the OE pin of the rom.

EA. EA. In 89c51 8751 or any other family member of the ateml 89c51 series all comewith on-chip rom to store programs, in such cases the EA pin is connected to the Vcc.

For family member 8031 and 8032 is which there is no on chip rom, code is stored inexternal memory and this is fetched by 8031. In that case EA pin must be connected to

GND pin to indicate that the code is stored externally.

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SPECIAL FUNCTION REGISTER ( SFR) ADDRESSES.

ACC ACCUMULATOR 0E0H

B B REGISTER 0F0H

PSW PROGRAM STATUS WORD 0D0H

SP STACK POINTER 81H

DPTR DATA POINTER 2 BYTES

DPL LOW BYTE OF DPTR 82H

DPH HIGH BYTE OF DPTR 83H

P0 PORT0 80H

P1 PORT1 90H

P2 PORT2 0A0H

P3 PORT3 0B0H

TMOD TIMER/COUNTER MODE CONTROL 89H

TCON TIMER COUNTER CONTROL 88H

TH0 TIMER 0 HIGH BYTE 8CH

TLO TIMER 0 LOW BYTE 8AH

TH1 TIMER 1 HIGH BYTE 8DH

TL1 TIMER 1 LOW BYTE 8BH

SCON SERIAL CONTROL 98H

SBUF SERIAL DATA BUFFER 99H

PCON POWER CONTROL 87H

INSTRUCTIONS

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SINGLE BIT INSTRUCTIONS.

SETB BIT SET THE BIT =1

CLR BIT CLEAR THE BIT =0

CPL BIT COMPLIMENT THE BIT 0 =1, 1=0

JB BIT,TARGET JUMP TO TARGET IF BIT =1

JNB BIT, TARGET JUMP TO TARGET IF BIT =0

JBC BIT,TARGET JUMP TO TARGET IF BIT =1 &THEN CLEAR THE BIT

MOV INSTRUCTIONS

MOV instruction simply copy the data from one location to another location

MOV D,S

Copy the data from(S) source to D(destination)

MOV R0,A ; Copy contents of A into Register R0

MOV R1,A ; Copy contents of A into register R1

MOV A,R3 ; copy contents of Register R3 into Accnmulator.

DIRECT LOADING THROUGH MOV

MOV A,#23H ; Direct load the value of 23h in A

MOV R0,#12h ; direct load the value of 12h in R0

MOV R5,#0F9H ; Load the F9 value in the Register R5

ADD INSTRUCTIONS.

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ADD instructions adds the source byte to the accumulator ( A) and place the result in the

Accumulator.

MOV A, #25H

ADD A,#42H ; BY this instructions we add the value 42h in Accumulator

( 42H+ 25H)

ADDA,R3 ;By this instructions we move the data from register r3 to

accumulator and then add the contents of the register into

accumulator .

SUBROUTINE CALL FUNCTION.

ACALL,TARGET ADDRESS

By this instructions we call subroutines with a target address within 2k bytes from the

current program counter.

LCALL, TARGET ADDRESS.

ACALL is a limit for the 2 k byte program counter, but for upto 64k byte we use

LCALL instructions.. Note that LCALL is a 3 byte instructions.ACALL is a two byte instructions.

AJMP TARGET ADDRESS.

This is for absolute jump

AJMPstand for absolute jump. It transfers program execution to the target address

unconditionally. The target address for this instruction must be

withib 2 k byte of program memory.

LJMP is also for absoltute jump. It tranfer program execution to the target addres

unconditionally. This is a 3 byte instructions LJMP jump to anyaddress within 64 k byte location.

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INSTRUCTIONS RELATED TO THE CARRY

JC TARGET

JUMP TO THE TARGET IF CY FLAG =1

JNC TARGET

JUMP TO THE TARGET ADDRESS IF CY FLAG IS = 0

INSTRUCTIONS RELASTED TO JUMP WITHACCUMULATOR

JZ TARGET

JUMP TO TARGET IF A = 0

JNZ TARGET

JUMP IF ACCUMULATOR IS NOT ZERO

This instructions jumps if registe A has a value other than zero

INSTRUCTIONS RELATED TO THE ROTATE

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RL A

ROTATE LEFT THE ACCUMULATOR

BY this instructions we rotate the bits of A left. The bits rotated out of A arerotated back into A at the opposite end

RR A

By this instruction we rotate the contents of the accumulator from right to

left from LSB to MSB

RRC A

This is same as RR A but difference is that the bit rotated out of register first

enter in to carry and then enter into MSB

RLC A

ROTATE A LEFT THROUGH CARRY

Same as above but but shift the data from MSB to carry and carry to LSB

RET

This is return from subroutine. This instructions is used to return from a

subroutine previously entered by instructions LCALL and ACALL.

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RET1

THIS is used at the end of an interrupt service routine. We use this

instructions after intruupt routine,

PUSH.

This copies the indicated byte onto the stack and increments SP by . This

instructions supports only direct addressing mode.

POP.

POP FROM STACK.

This copies the byte pointed to be SP to the location whose direct address is

indicated, and decrements SP by 1. Notice that this instructions supports

only direct addressing mode.

DPTR INSTRUCTIONS.

MOV DPTR,#16 BIT VALUE

LOAD DATA POINTER

This instructions load the 16 bit dptr register with a 16 bit immediate value

MOV C A,@A+DPTR

This instructions moves a byte of data located in program ROM into register

A. This allows us to put strings of data, such as look up table elements.

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MOVC A,@A+PC

This instructions moves a byte of data located in the program area to A. the address of thedesired byte of data is formed by adding the program counter ( PC) register to the original

value of the accumulator.

INC BYTE

This instructions add 1 to the register or memory location specified by the

operand.

INC A

INC Rn

INC DIRECT

DEC BYTE

This instructions subtracts 1 from the byte operand. Note that CY is

unchanged

DEC A

DEC Rn

DEC DIRECT

ARITHMATIC INSTRUCTIONS.

ANL dest-byte, source-byte

This perform a logical AND operation

This performs a logical AND on the operands, bit by bit, storing the result in

the destination. Notice that both the source and destination values are byte

size only

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`

DIV AB

This instructions divides a byte accumulator by the byte in register B. It is

assumed that both register A and B contain an unsigned byte. After the

division the quotient will be in register A and the remainder in register B.

TMOD ( TIMER MODE ) REGISTER

Both timer is the 89c51 share the one register TMOD. 4 LSB bit for the timer 0 and 4MSB for the timer 1.

In each case lower 2 bits set the mode of the timer

Upper two bits set the operations.

GATE: Gating control when set. Timer/counter is enabled only while the INTXpin is high and the TRx control pin is set. When cleared, the timer is enabled wheneverthe TRx control bit is set

C/T : Timer or counter selected cleared for timer operation ( input from internalsystem clock)

M1 Mode bit 1

M0 Mode bit 0

M1 M0 MODE OPERATING MODE

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0 0 0 13 BIT TIMER/MODE

0 1 1 16 BIT TIMER MODE

1 0 2 8 BIT AUTO RELOAD

1 1 3 SPLIT TIMER MODE

PSW ( PROGRAM STATUS WORD)

CY PSW.7 CARRY FLAG

AC PSW.6 AUXILIARY CARRY

F0 PSW.5 AVAILABLE FOR THE USER FRO GENERAL PURPOSE

RS1 PSW.4 REGISTER BANK SELECTOR BIT 1

RS0 PSW.3 REGISTER BANK SELECTOR BIT 0

0V PSW.2 OVERFLOW FLAG

-- PSW.1 USER DEFINABLE BIT

P PSW.0 PARITY FLAG SET/CLEARED BY HARDWARE

PCON REGISATER ( NON BIT ADDRESSABLE)

If the SMOD = 0 ( DEFAULT ON RESET)

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TH1 = CRYSTAL FREQUENCY

256---- ____________________

384 X BAUD RATE

If the SMOD IS = 1 CRYSTAL FREQUENCY

TH1 = 256--------------------------------------

192 X BAUD RATE

There are two ways to increase the baud rate of data transfer in the 8051

1. To use a higher frequency crystal

2. To change a bit in the PCON register

PCON register is an 8 bit register . Of the 8 bits, some are unused, and some are used forthe power control capability of the 8051. the bit which is used for the serial

communication is D7, the SMOD bit. When the 8051 is powered up, D7 ( SMOD BIT)

OF PCON register is zero. We can set it to high by software and thereby double the

baud rate

BAUD RATE COMPARISION FOR SMOD = 0 AND SMOD =1

TH1 ( DECIMAL) HEX SMOD =0 SMOD =1

-3 FD 9600 19200

-6 FA 4800 9600

-12 F4 2400 4800

-24 E8 1200 2400

XTAL = 11.0592 MHZ

IE ( INTERRUPT ENABLE REGISTOR)

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EA IE.7 Disable all interrupts if EA = 0, no interrupts is acknowledgedIf EA is 1, each interrupt source is individually enabled or disbaledBy sending or clearing its enable bit.

IE.6 NOT implemented

ET2 IE.5 enables or disables timer 2 overflag in 89c52 only

ES IE.4 Enables or disables all serial interrupt

ET1 IE.3 Enables or Disables timer 1 overflow interrupt

EX1 IE.2 Enables or disables external interrupt

ET0 IE.1 Enables or Disbales timer 0 interrupt.

EX0 IE.0 Enables or Disables external interrupt 0

INTERRUPT PRIORITY REGISTER

If the bit is 0, the corresponding interrupt has a lower priority and if the bit is 1 thecorresponding interrupt has a higher priority

IP.7 NOT IMPLEMENTED, RESERVED FOR FUTURE USE.

IP.6 NOT IMPLEMENTED, RESERVED FOR FUTURE USE

PT2 IP.5 DEFINE THE TIMER 2 INTERRUPT PRIORITY LELVEL

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PS IP.4 DEFINES THE SERIAL PORT INTERRUPT PRIORITY LEVEL

PT1 IP.3 DEFINES THE TIMER 1 INTERRUPT PRIORITY LEVEL

PX1 IP.2 DEFINES EXTERNAL INTERRUPT 1 PRIORITY LEVEL

PT0 IP.1 DEFINES THE TIMER 0 INTERRUPT PRIORITY LEVEL

PX0 IP.0 DEFINES THE EXTERNAL INTERRUPT 0 PRIORITY LEVEL

SCON: SERIAL PORT CONTROL REGISTER , BIT ADDRESSABLE

SCON

SM0 : SCON.7 Serial Port mode specifier

SM1 : SCON.6 Serial Port mode specifier

SM2 : SCON.5

REN : SCON.4 Set/cleared by the software to Enable/disable reception

TB8 : SCON.3 The 9th bit that will be transmitted in modes 2 and 3, Set/clearedBy software

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RB8 : SCON.2 In modes 2 &3, is the 9th data bit that was received. In mode 1,If SM2 = 0, RB8 is the stop bit that was received. In mode 0RB8 is not used

T1 : SCON.1 Transmit interrupt flag. Set by hardware at the end of the 8th

bitTime in mode 0, or at the beginning of the stop bit in the otherModes. Must be cleared by software

R1 SCON.0 Receive interrupt flag. Set by hardware at the end of the 8th bitTime in mode 0, or halfway through the stop bit time in the otherModes. Must be cleared by the software.

TCON TIMER COUNTER CONTROL REGISTER

This is a bit addressable

TF1 TCON.7 Timer 1 overflow flag. Set by hardware when the Timer/Counter 1Overflows. Cleared by hardware as processor

TR1 TCON.6 Timer 1 run control bit. Set/cleared by software to turn TimerCounter 1 On/off

TF0 TCON.5 Timer 0 overflow flag. Set by hardware when the timer/counter 0

Overflows. Cleared by hardware as processor

TR0 TCON.4 Timer 0 run control bit. Set/cleared by software to turn timerCounter 0 on/off.

IE1 TCON.3 External interrupt 1 edge flag

ITI TCON.2 Interrupt 1 type control bit

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IE0 TCON.1 External interrupt 0 edge

IT0 TCON.0 Interrupt 0 type control bit.

- 8051 Instruction Set

Arithmetic Operations

Mnemonic Description Size Cycles

ADD A,Rn Add register to Accumulator (ACC). 1 1

ADD A,direct Add direct byte to ACC. 2 1

ADD A,@Ri Add indirect RAM to ACC . 1 1

ADD A,#data Add immediate data to ACC . 2 1

ADDC A,Rn Add register to ACC with carry . 1 1

ADDC A,direct Add direct byte to ACC with carry. 2 1

ADDC A,@Ri Add indirect RAM to ACC with carry. 1 1

ADDC A,#data Add immediate data to ACC with carry. 2 1

SUBB A,Rn Subtract register from ACC with borrow. 1 1

SUBB A,direct Subtract direct byte from ACC with borrow 2 1

SUBB A,@Ri Subtract indirect RAM from ACC with borrow. 1 1

SUBB A,#data Subtract immediate data from ACC with borrow. 2 1

INC A Increment ACC. 1 1

INC Rn Increment register. 1 1

INC direct Increment direct byte. 2 1

INC @Ri Increment indirect RAM. 1 1

DEC A Decrement ACC. 1 1

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DEC Rn Decrement register. 1 1

DEC direct Decrement direct byte. 2 1

DEC @Ri Decrement indirect RAM. 1 1

INC DPTR Increment data pointer. 1 2

MUL AB Multiply A and B Result: A


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XRL A,direct Exclusive OR direct byte to ACC. 2 1

XRL A,@Ri Exclusive OR indirect RAM to ACC. 1 1

XRL A,#data Exclusive OR immediate data to ACC. 2 1

XRL direct,A Exclusive OR ACC to direct byte. 2 1

XRL direct,#data XOR immediate data to direct byte. 3 2

CLR A Clear ACC (set all bits to zero). 1 1

CPL A Compliment ACC. 1 1

RL A Rotate ACC left. 1 1

RLC A Rotate ACC left through carry. 1 1

RR A Rotate ACC right. 1 1

RRC A Rotate ACC right through carry. 1 1

SWAP A Swap nibbles within ACC. 1 1

Data Transfer


MOV A,Rn Move register to ACC. 1 1

MOV A,direct Move direct byte to ACC.2 1

MOV A,@Ri Move indirect RAM to ACC. 1 1

MOV A,#data Move immediate data to ACC. 2 1

MOV Rn,A Move ACC to register. 1 1

MOV Rn,direct Move direct byte to register. 2 2

MOV Rn,#data Move immediate data to register. 2 1

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MOV direct,A Move ACC to direct byte. 2 1

MOV direct,Rn Move register to direct byte. 2 2

MOV direct,direct Move direct byte to direct byte. 3 2

MOV direct,@Ri Move indirect RAM to direct byte. 2 2

MOV direct,#data Move immediate data to direct byte. 3 2

MOV @Ri,A Move ACC to indirect RAM. 1 1

MOV @Ri,direct Move direct byte to indirect RAM. 2 2

MOV @Ri,#data Move immediate data to indirect RAM. 2 1

MOV DPTR,#data16 Move immediate 16 bit data to data pointer register. 3 2

MOVC A,@A+DPTR Move code byte relative to DPTR to ACC (16 bit address).1 2

MOVC A,@A+PC Move code byte relative to PC to ACC (16 bit address).1 2

MOVX A,@Ri Move external RAM to ACC (8 bit address). 1 2

MOVX A,@DPTR Move external RAM to ACC (16 bit address). 1 2

MOVX @Ri,A Move ACC to external RAM (8 bit address). 1 2

MOVX @DPTR,A Move ACC to external RAM (16 bit address). 1 2

PUSH direct Push direct byte onto stack. 2 2

POP direct Pop direct byte from stack. 2 2

XCH A,Rn Exchange register with ACC. 1 1

XCH A,direct Exchange direct byte with ACC. 2 1

XCH A,@Ri Exchange indirect RAM with ACC. 1 1

XCHD A,@Ri Exchange low order nibble of indirectRAM with low order nibble of ACC 1 1

Boolean Variable Manipulation

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CLR C Clear carry flag. 1 1

CLR bit Clear direct bit. 2 1

SETB C Set carry flag. 1 1

SETB bitSet direct bit 2 1

CPL C Compliment carry flag. 1 1

CPL bit Compliment direct bit. 2 1

ANL C,bit AND direct bit to carry flag. 2 2

ANL C,/bit AND compliment of direct bit to carry. 2 2

ORL C,bit OR direct bit to carry flag. 2 2

ORL C,/bit OR compliment of direct bit to carry. 2 2

MOV C,bit Move direct bit to carry flag. 2 1

MOV bit,C Move carry to direct bit. 2 2

JC rel Jump if carry is set. 2 2

JNC rel Jump if carry is not set. 2 2

JB bit,rel Jump if direct bit is set. 3 2

JNB bit,rel Jump if direct bit is not set. 3 2

JBC bit,rel Jump if direct bit is set & clear bit. 3 2

Program BranchingMnemonic Description Size Cycles

ACALL addr11 Absolute subroutine call. 2 2

LCALL addr16 Long subroutine call. 3 2

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RET Return from subroutine. 1 2

RETI Return from interrupt. 1 2

AJMP addr11 Absolute jump. 2 2

LJMP addr16 Long jump. 3 2

SJMP rel Short jump (relative address). 2 2

JMP @A+DPTR Jump indirect relative to the DPTR. 1 2

JZ rel Jump relative if ACC is zero. 2 2

JNZ rel Jump relative if ACC is not zero. 2 2

CJNE A,direct,rel Compare direct byte to ACC and jump if not equal. 3 2

CJNE A,#data,rel Compare immediate byte to ACC and jump if not equal.3 2

CJNE Rn,#data,rel Compare immediate byte to register and jump if not equal.32

CJNE @Ri,#data,rel Compare immediate byte to indirect and jump if not equal.32

DJNZ Rn,rel Decrement register and jump if not zero. 2 2

DJNZ direct,rel Decrement direct byte and jump if not zero. 3 2

The RW line is the "Read/Write" control line. When RW is low (0), the information on

I

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HOW TO PROGRAM BLANKCHIP.

8051 micro controller

The 8051

The 8051 developed and launched in the early 80`s, is one of the mostpopular micro controller in use today. It has a reasonably large amount ofbuilt in ROM and RAM. In addition it has the ability to access external

memory.

The generic term `8x51` is used to define the device. The value of x definingthe kind of ROM, i.e. x=0, indicates none, x=3, indicates mask ROM, x=7,indicates EPROM and x=9 indicates EEPROM or Flash.

Different micro controllers in market.

PIC One of the famous microcontrollers used in the

industries. It is based on RISC Architecture which makes themicrocontroller process faster than other microcontroller.

INTEL These are the first to manufacture

microcontrollers. These are not as sophisticated other microcontrollersbut still the easiest one to learn.

ATMEL Atmels AVR microcontrollers are one of the most

powerful in the embedded industry. This is the only microcontrollerhaving 1kb of ram even the entry stage. But it is unfortunate that inIndia we are unable to find this kind of microcontroller.

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Intel 8051

Intel 8051 is CISC architecture which is easy to program in assemblylanguage and also has a good support for High level languages.

The memory of the microcontroller can be extended up to 64k.

This microcontroller is one of the easiest microcontrollers to learn.

The 8051 microcontroller is in the field for more than 20 years. There arelots of books and study materials are readily available for 8051.

First of all we select and open the assembler and wrote a program code in

the file. After wrote a software we assemble the software by using internal

assembler of the 8051 editor. If there is no error then assembler assemble

the software abd 0 error is show the output window.

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now assembler generate a ASM file and HEX file. This hex file is useful for

us to program the blank chip.

Now we transfer the hex code into the blank chip with the help of serial

programmer kit. In the programmer we insert a blank chip 0f 89s51 series .

these chips are multi time programmable chip. This programming kit is

seperatally available in the market and we transfer the hex code into blank

chip with the help of the serial programmer kit

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NOTES ONLCD

LCD DETAIL .

Frequently, an 8051 program must interact with the outside world using input and output

devices that communicate directly with a human being. One of the most common devices

attached to an 8051 is an LCD display. Some of the most common LCDs connected to

the 8051 are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20

characters per line by 2 lines, respectively.

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HD44780U, which refers to the controller chip which receives data from an external

source (in this case, the 8051) and communicates directly with the LCD.

44780 BACKGROUND

AN EXAMPLE HARDWARE CONFIGURATION

DB0 EQU P1.0

DB1 EQU P1.1

DB2 EQU P1.2

DB3 EQU P1.3

DB4 EQU P1.4

DB5 EQU P1.5

DB6 EQU P1.6

DB7 EQU P1.7

EN EQU P3.7

RS EQU P3.6

RW EQU P3.5

DATA EQU P1Having established the above equates, we may now refer to our I/O lines by their 44780

name. For example, to set the RW line high (1), we can execute the following insutrction:

SETB RW

HANDLING THE EN CONTROL LINE

with the following instruction:

SETB EN

And once we've finished setting up our instruction with the other control lines and data

bus lines, we'll always bring this line back low:

CLR EN

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Programming Tip: The LCD interprets and executes our command at the instant

the EN line is brought low. If you never bring EN low, your instruction will never

be executed. Additionally, when you bring EN low and the LCD executes your

instruction, it requires a certain amount of time to execute the command. The time

it requires to execute an instruction depends on the instruction and the speed of

the crystal which is attached to the 44780's oscillator input.

CHECKING THE BUSY STATUS OF THE LCD

As previously mentioned, it takes a certain amount of time for each instruction to be

executed by the LCD. The delay varies depending on the frequency of the we will usethis code every time we send an instruction to

WAIT_LCD:

SETB EN ;Start LCD command

CLR RS ;It's a command

SETB RW ;It's a read command

MOV DATA,#0FFh ;Set all pins to FF initially

MOV A,DATA ;Read the return value

JB ACC.7,WAIT_LCD ;If bit 7 high, LCD still busy

CLR EN ;Finish the command

CLR RW ;Turn off RW for future commands

RET

Thus, our standard practice will be to send an instruction to the LCD and then call our

WAIT_LCD routine to wait until the instruction is completely executed by the LCD.

This will assure that our program gives the LCD the time it needs to execute instructions

and also makes our program compatible with any LCD, regardless of how fast or slow it

is.

Programming Tip: The above routine does the job of waiting for the LCD, but

were it to be used in a real application a very definite improvement would need to

be made: as written, if the LCD never becomes "not busy" the program will

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effectively "hang," waiting for DB7 to go low. If this never happens, the program

will freeze. Of course, this should never happen and won't happen when the

hardware is working properly. But in a real application it would be wise to put

some kind of time limit on the delay--for example, a maximum of 256 attempts to

wait for the busy signal to go low. This would guarantee that even if the LCD

hardware fails, the program would not lock up.

INITIALIZING THE LCD

SETB ENCLR RSMOV DATA,#38hCLR ENLCALL WAIT_LCD

Programming Tip: The LCD command 38h is really the sum of a number of

option bits. The instruction itself is the instruction 20h ("Function set"). However,

to this we add the values 10h to indicate an 8-bit data bus plus 08h to indicate that

the display is a two-line display.

We've now sent the first byte of the initialization sequence. The second byte of the

initialization sequence is the instruction 0Eh. Thus we must repeat the initialization code

from above, but now with the instruction. Thus the next code segment is:

SETB EN

CLR RS

MOV DATA,#0Eh

CLR EN

LCALL WAIT_LCD

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Programming Tip: The command 0Eh is really the instruction 08h plus 04h to

turn the LCD on. To that an additional 02h is added in order to turn the cursor on.

The last byte we need to send is used to configure additional operational parameters of

the LCD. We must send the value 06h.

SETB EN

CLR RS

MOV DATA,#06h

CLR EN

LCALL WAIT_LCD

Programming Tip: The command 06h is really the instruction 04h plus 02h to

configure the LCD such that every time we send it a character, the cursor position

automatically moves to the right.

So, in all, our initialization code is as follows:

INIT_LCD:

SETB EN

CLR RS

MOV DATA,#38h

CLR EN

LCALL WAIT_LCD

SETB EN

CLR RS

MOV DATA,#0Eh

CLR EN

LCALL WAIT_LCD

SETB EN

CLR RS

MOV DATA,#06h

CLR EN

LCALL WAIT_LCD

RET

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Having executed this code the LCD will be fully initialized and ready for us to send

display data to it.

CLEARING THE DISPLAY

When the LCD is first initialized, the screen should automatically be cleared by the 447e,

it's a good idea to make it a subroutine:

CLEAR_LCD:

SETB EN

CLR RS

MOV DATA,#01h

CLR EN

LCALL WAIT_LCD

RET

How that we've written a "Clear Screen" routine, we may clear the LCD at any time by

simply executing an LCALL CLEAR_LCD.

Programming Tip: Executing the "Clear Screen" instruction on the LCD also

positions the cursor in the upper left-hand corner as we would expect.

WRITING TEXT TO THE LCD

Now we get to the real meat of what we're trying to do: All this effort is really so we can

display text on the LCD. Really, we're pretty much done.

Once again, writing text to the LCD is something we'll almost certainly want to do over

and over--so let's make it a subroutine.

WRITE_TEXT:

SETB EN

SETB RS

MOV DATA,A

CLR EN

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LCALL WAIT_LCD

RET

The WRITE_TEXT routine that we just wrote will send the character in the accumulator

to the LCD which will, in turn, display it. Thus to display text on the LCD all we need to

do is load the accumulator with the byte to display and make a call to this routine. Pretty

easy, huh?

A "HELLO WORLD" PROGRAM

Now that we have

LCALL INIT_LCD

LCALL CLEAR_LCD

MOV A,#'H'

LCALL WRITE_TEXT

MOV A,#'E'

LCALL WRITE_TEXT

MOV A,#'L'

LCALL WRITE_TEXT

MOV A,#'L'LCALL WRITE_TEXT

MOV A,#'O'

LCALL WRITE_TEXT

MOV A,#' '

LCALL WRITE_TEXT

MOV A,#'W'

LCALL WRITE_TEXT

MOV A,#'O'

LCALL WRITE_TEXT

MOV A,#'R'

LCALL WRITE_TEXT

MOV A,#'L'

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LCALL WRITE_TEXT

MOV A,#'D'

LCALL WRITE_TEXT

The above "Hello World" program should, when executed, initialize the LCD, clear the

LCD screen, and display "Hello World" in the upper left-hand corner of the display.

CURSOR POSITIONING

The

Thus, the

SETB EN

CLR RS

MOV DATA,#0C4h

CLR EN

LCALL WAIT_LCD

The above code will position the cursor on line 2, character 10. To display "Hello" in the

upper left-hand corner with the word "World" on the second line at character position 10

just requires us to insert the above code into our existing "Hello World" program. This

results in the following:

LCALL INIT_LCD

LCALL CLEAR_LCD

MOV A,#'H'

LCALL WRITE_TEXT

MOV A,#'E'

LCALL WRITE_TEXT

MOV A,#'L'

LCALL WRITE_TEXT

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MOV A,#'L'

LCALL WRITE_TEXT

MOV A,#'O'

LCALL WRITE_TEXT

SETB EN

CLR RS

MOV DATA,#0C4h

CLR EN

LCALL WAIT_LCD

MOV A,#'W'

LCALL WRITE_TEXT

MOV A,#'O'

LCALL WRITE_TEXT

MOV A,#'R'

LCALL WRITE_TEXT

MOV A,#'L'

LCALL WRITE_TEXT

MOV A,#'D'

LCALL WRITE_TEXT

PIN WISE DETAIL OF LCD

1. Vss GROUND

2. Vcc +5VOLT SUPPLY

3 Vee POWER SUPPLY TO CONTROL CONTRAST

4. RS RS = 0 TO SELECT COMMAND REGISTER RS = 1 TO SELECT DATA REGISTER

5. R/W R/W = 0 FOR WRITER/W = 1 FOR READ

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F. DISPLAY ON CURSOR BLINKING.

10. SHIFT CURSOR POSITION TO LEFT

14. SHIFT CURSOR POSITION TO RIGHT

18. SHIFT THE ENTIRE DISPLAY TO THE LEFT

1C SHIFT THE ENTIRE DISPLAY TO THE RIGHT

80 FORCE CURSOR TO BEGINNING OF IST LINE

C0 FORCE CURSOR TO BEGINNING OF 2ND LINE

38 2 LINES AND 5 X 7 MATRIX

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77/103

org 000bh

reti

org 0013h

reti

org 001bh

reti

org 0023h

reti

da

a

mov pulse_cont0_hi,a

mov a,pulse_cont0_hi

cjne a,#10h,inte0_end

mov pulse_cont0_lo,#00h

mov pulse_cont0_hi,#00h

inte0_end:

mov a,pulse_cont0_lo

mov 1ah,a

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mov 1bh,#0d

lcall DELAY_RM

LCALL write


mov 1ah,a

mov 1bh,#1d

lcall DELAY_RM

LCALL write

setb ex0

pop acc

pop psw

reti

TIMER_0:

push psw

push acc

clr tr0

mov tl0,#0b2h

mov th0,#06Ch

mov a,cont

add a,#01h

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mov cont,a

cjne a,#20d,TIMER_NXT

mov cont,#0d

clr flag1

da

a

mov pulse_cont1_lo,a


addc a,#0d

da

a

mov pulse_cont1_hi,a


cjne a,#10h,inte1_end



inte1_end:


mov 1ah,a

mov 1bh,#2d

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lcall DELAY_RM

LCALL write


mov 1ah,a

mov 1bh,#3d

lcall DELAY_RM

LCALL write

setb ex1

pop acc

pop psw

reti

main:

mov psw,#00h

mov sp,#070h

mov tmod,#21h

mov tcon,#05h

mov scon,#50h

anl pcon,#7fh

mov ie,#00h

mov ip,#00h

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mov tl1,#0fdh

mov th1,#0fdh

mov tl0,#0b0h

mov th0,#03ch

mov p0,#0ffh

mov p1,#0ffh

mov p2,#0ffh

mov p3,#0ffh





clr lcd_rs

clr lcd_rw

clr lcd_en

lcall INIT_LCD

lcall CLR_LCD

lcall

data_cheke

mov dptr,#MSG0

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83/103

lcall

DELAY


anl a,#0fh

ADD a,#30h

lcall

TRANS

lcall

DELAY


anl a,#0fh

ADD a,#30h

lcall

TRANS

lcall

DELAY


anl a,#0fh

ADD a,#30h

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lcall

TRANS

lcall

DELAY


anl a,#0fh

ADD a,#30h

lcall

TRANS

lcall

DELAY


anl a,#0fh

lcall

TRANS

lcall

DELAY


anl a,#0fh

ADD a,#30h

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lcall

TRANS

lcall

DELAY

mov

a,#13d

lcall

TRANS

lcall

DELAY

ljmp wait

display:

mov LCD_DATA,#08dh

lcall COMMAND_BYTE

lcall DELAY41


anl a,#0fh

ADD a,#30h

mov LCD_DATA,a

lcall DATA_BYTE

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lcall DELAY41

mov LCD_DATA,#08eh

lcall COMMAND_BYTE

lcall DELAY41


swap a

anl a,#0fh

ADD a,#30h

mov LCD_DATA,a

lcall DATA_BYTE

lcall DELAY41

mov LCD_DATA,#08fh

lcall COMMAND_BYTE

lcall DELAY41


anl a,#0fh

ADD a,#30h

mov LCD_DATA,a

lcall DATA_BYTE

lcall DELAY41

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mov LCD_DATA,#0cdh

lcall COMMAND_BYTE

lcall DELAY41


anl a,#0fh

ADD a,#30h

mov LCD_DATA,a

lcall DATA_BYTE

lcall DELAY41

mov LCD_DATA,#0ceh

lcall COMMAND_BYTE

lcall DELAY41


swap a

anl a,#0fh

ADD a,#30h

mov LCD_DATA,a

lcall DATA_BYTE

lcall DELAY41

mov LCD_DATA,#0cfh

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lcall COMMAND_BYTE

lcall DELAY41


anl a,#0fh

ADD a,#30h

mov LCD_DATA,a

lcall DATA_BYTE

lcall DELAY41

ret

TRANS:

mov

sbuf,a

jnb ti

lcall

ELAY_RM

ret

LINE_1:

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mov LCD_DATA,#080h

lcall COMMAND_BYTE

lcall DELAY41

lcall WRITE_MSG

ret

LINE_2:

mov LCD_DATA,#0c0h

lcall COMMAND_BYTE

lcall DELAY41

lcall WRITE_MSG

ret

INIT_LCD:

mov LCD_DATA,#038h

lcall COMMAND_BYTE

lcall DELAY41

mov LCD_DATA,#038h

lcall COMMAND_BYTE

lcall DELAY41

mov LCD_DATA,#038h

lcall COMMAND_BYTE

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lcall DELAY41

mov LCD_DATA,#038h

lcall COMMAND_BYTE

lcall DELAY41

mov LCD_DATA,#008h

lcall COMMAND_BYTE

lcall DELAY41

mov LCD_DATA,#00ch

lcall COMMAND_BYTE

lcall DELAY41

mov LCD_DATA,#006h

lcall COMMAND_BYTE

lcall DELAY41

ret

CLR_LCD:

mov LCD_DATA,#001h

lcall COMMAND_BYTE

lcall DELAY41

ret

WRITE_MSG:

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mov a,#00h

movc a,@a+dptr

cjne a,#'$',WRITE_CONT

ret

WRITE_CONT:

mov LCD_DATA,a

lcall DATA_BYTE

ljmp WRITE_MSG

COMMAND_BYTE:

clr lcd_rs

lcall DELAY

ljmp CMD10

DATA_BYTE:

setb lcd_rs

lcall DELAY

CMD10:

clr lcd_rw

lcall DELAY

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setb lcd_en

lcall DELAY

clr lcd_en

lcall DELAY

ret

DELAY:

mov r0,#10d

DEL:

djnz r0,DEL

ret

DELAY1:

mov r0,#0d

mov r1,#0d

DEL1:

djnz r0,DEL1

djnz r1,DEL1

ret

DELAY_RM:

mov r0,#0d

mov r1,#5d

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DEL_RM:

djnz r0,DEL_RM

djnz r1,DEL_RM

ret

DELAY10:

mov r0,#0d

mov r1,#0d

mov r2,#10d

DEL10:

djnz r0,DEL10

djnz r1,DEL10

djnz r2,DEL10

ret

DELAY41:

mov r0,#0d

mov r1,#15d

DLP410:

djnz r0,DLP410

djnz r1,DLP410

ret

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data_cheke:

mov 1bh,#4d

lcall DELAY_RM

lcall read

mov

a,19h

cjne

a,#0d,data_chanj

ljmp

data_load_eeprom

data_chanj:

mov

1ah,#0d

mov

1bh,#0d

lcall DELAY_RM

LCALL write

mov

1ah,#0d

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mov

1bh,#1d

lcall DELAY_RM

LCALL write

mov

1ah,#0d

mov

1bh,#2d

lcall DELAY_RM

LCALL write

mov

1ah,#0d

mov

1bh,#3d

lcall DELAY_RM

LCALL write

mov

1ah,#0d

mov

1bh,#4d

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97/103

ret

;;;;;;;;;;;;; for 24c04 ;;;;;;;;;;;;;;;

read: PUSH B

MOV B, A

ACALL START

JC NOBUS

MOV A, #00H

ORL A, #0A0H

ACALL SHOUT

JC XR1

MOV A,1bh

ACALL SHOUT

JC XR1

MOV A, B

lCALL R_CRNT

lJMP XR2

XR1: lCALL STOP

NOBUS: SETB 1

XR2:

MOV 19h, A

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POP B

RET

STAR

wireless energy meter data logger on pc

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