06-04-2010, 05:18 PM
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SEMINAR ON MICROPROCESSOR BASED LENGTH MEASUREMENT
INTRODUCTION
An electronic scale and length measurement apparatus including electronic length measurement transducer for providing an electrical signal indicative of the length of an object to be measured.
These signals are processed by an electronic signal processing circuit including a microprocessor, a ROM and a transducer.
CONVENTIONAL LENGTH MEASURING DEVICE
The conventional length measuring devices are that they have no memory.
Readouts are analog based.
Cannot be hand held and are not easily portable.
Do not include structure to measure  the length.
MICROPROCESSOR BASED LENGTH MEASURING DEVICE
Measured by means of an apertured tape .
A pair of light emitting diodes (LED's) and photocells provide a plurality of electronic pulses as a function of the length
The pulses are counted by the microprocessor and the count is converted to a digital value indicative of the length of the device
Program stored in the ROM causes the pulse to be counted by incrementing the count when the tape is pulled out and decrementing when the tape is retracted.
DESIGN OF A MICROCONTROLLER BASED LENGTH MEASUREMENT SYSTEM FOR A CONTINUOUSLY ROLLING CLOTH OR PAPER
8031,ROM less version of 8051.
Accuracy of less than 1 cm.
Principle of photoelectric tachometer is used to sense the displacement
The pulses are converted to form readable by on-chip TIMER.
The equivalent length is obtained by multiplying the no of pulses with a caliberation constant.
TRANSDUCER
We use mouse as a displacement trasducer.
The mouse contains two sets of opto-electrical arrangements one for X-direction movement and other for Y-direction movement.
The length of the cloth or paper to be measured moves under the mouse so as to rotate the mouse ball.
The no. of electrical pulses generated is propertional to the length of the cloth.
INTERNAL MECHANISM OF MOUSE
MOUSE OVER ROLLING CLOTH
SIGNAL CONDITIONING
The signal generated by infrared opto-electrical arrangement needs to be converted into proper rectangular pulse.
This requires a clamping circuit and comparator arrangement as shown in the next figure.
The above circuit clamps the waveform generated by the mouse to 0 volts
The comparator further converts it to a rectangular pulse sequence of amplitude 0-5 volts.
THE WAVE SHAPING CIRCUIT
MICROCONTROLLER SYSTEM
The microprocessor system designed for this purpose contains following main functional units.
1.8031 circuit
2.EPROM 2732,RAM 6264 and interfacing circuit
3.Display unit
The 8031 circuit contains microcontroller IC 8031, its reset circuit and an octal latch 74373 to separate the multiplexed address and data lines.
MICROCONTROLLER SYSTEM
The memory and address decoding circuit contain the external program memory IC 2732, external data RAM 6264 and the address decoding circuit.
The ICs 74138 and 7408 are used for address decoding of the EPROM and RAM.
The complete system runs at 10 MHz frequency.
ADVANTAGES
This is very compact.
it is very accurate and that accurate calibration of the device may be obtained.
apparatus includes a memory whereby previously measured
lengths may be stored and recalled.
a digital readout is provided which is more easy to read than the prior art analog readouts.
CONCLUSION
Microprocessor based length measurement system provides an
easier basis for length measurement eradicating the difficulties
that occur in conventional instruments. Moreover this is a solid
alternative to conventional length measuring devices.
SEMINAR ON MICROPROCESSOR BASED LENGTH MEASUREMENT
INTRODUCTION
An electronic scale and length measurement apparatus including electronic length measurement transducer for providing an electrical signal indicative of the length of an object to be measured.
These signals are processed by an electronic signal processing circuit including a microprocessor, a ROM and a transducer.
CONVENTIONAL LENGTH MEASURING DEVICE
The conventional length measuring devices are that they have no memory.
Readouts are analog based.
Cannot be hand held and are not easily portable.
Do not include structure to measure  the length.
MICROPROCESSOR BASED LENGTH MEASURING DEVICE
Measured by means of an apertured tape .
A pair of light emitting diodes (LED's) and photocells provide a plurality of electronic pulses as a function of the length
The pulses are counted by the microprocessor and the count is converted to a digital value indicative of the length of the device
Program stored in the ROM causes the pulse to be counted by incrementing the count when the tape is pulled out and decrementing when the tape is retracted.
DESIGN OF A MICROCONTROLLER BASED LENGTH MEASUREMENT SYSTEM FOR A CONTINUOUSLY ROLLING CLOTH OR PAPER
8031,ROM less version of 8051.
Accuracy of less than 1 cm.
Principle of photoelectric tachometer is used to sense the displacement
The pulses are converted to form readable by on-chip TIMER.
The equivalent length is obtained by multiplying the no of pulses with a caliberation constant.
TRANSDUCER
We use mouse as a displacement trasducer.
The mouse contains two sets of opto-electrical arrangements one for X-direction movement and other for Y-direction movement.
The length of the cloth or paper to be measured moves under the mouse so as to rotate the mouse ball.
The no. of electrical pulses generated is propertional to the length of the cloth.
INTERNAL MECHANISM OF MOUSE
MOUSE OVER ROLLING CLOTH
SIGNAL CONDITIONING
The signal generated by infrared opto-electrical arrangement needs to be converted into proper rectangular pulse.
This requires a clamping circuit and comparator arrangement as shown in the next figure.
The above circuit clamps the waveform generated by the mouse to 0 volts
The comparator further converts it to a rectangular pulse sequence of amplitude 0-5 volts.
THE WAVE SHAPING CIRCUIT
MICROCONTROLLER SYSTEM
The microprocessor system designed for this purpose contains following main functional units.
1.8031 circuit
2.EPROM 2732,RAM 6264 and interfacing circuit
3.Display unit
The 8031 circuit contains microcontroller IC 8031, its reset circuit and an octal latch 74373 to separate the multiplexed address and data lines.
MICROCONTROLLER SYSTEM
The memory and address decoding circuit contain the external program memory IC 2732, external data RAM 6264 and the address decoding circuit.
The ICs 74138 and 7408 are used for address decoding of the EPROM and RAM.
The complete system runs at 10 MHz frequency.
ADVANTAGES
This is very compact.
it is very accurate and that accurate calibration of the device may be obtained.
apparatus includes a memory whereby previously measured
lengths may be stored and recalled.
a digital readout is provided which is more easy to read than the prior art analog readouts.
CONCLUSION
Microprocessor based length measurement system provides an
easier basis for length measurement eradicating the difficulties
that occur in conventional instruments. Moreover this is a solid
alternative to conventional length measuring devices.