International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
PC-based Oscilloscope
Thakurendra Singh1, Rohit Tyagi2, Mayank Singh3, Pushpendra Singh4,Kuldeep Kardam5
1
(Faculty PG Department of Electronics & Communication Engineering, Raja Balwant Singh Engineering
Technical Campus, Bichpuri, Agra, U. P., India)
2, 3, 4, 5
(Final Year Students Electronics & Communication Engineering, Raja Balwant Singh Engineering Technical
Campus, Agra, U. P., India)
Abstract : To trace the signal is very important for every
person who is working with the electronic components.
Generally to trace the signals the people prefer the
digital oscilloscope, which is used to display the output
or the paused waveform on the display. We chacterised
the digital oscilloscope with the help of their sample
rate, the analog bandwidth, memory capacity of
oscilloscope and the bit-resolution. In the starting era,
the oscilloscopes have the bandwidth of nearly 100MHz
with an 8-bit resolution of the data, it has two channels,
and at a sample rate is near about 1Gb/s. These
oscilloscopes were limited by their internal memory
capacity due to which the user trade between
measurement duration and the resolution of the data.
The capacity of the measurement of the oscilloscope
increases but with the increase in the memory capacity
the price were also increases. We can reduce the cost of
the oscilloscope by using an external PC instead of the
internal memory of the oscilloscope. But when we talk
about the PC-based Oscilloscope, these oscilloscopes
are less expensive but the performance is limited by the
data transfer rate due to the Pc-bus connection. The PIC
12F675 has a word length of 1024 for program memory,
and a 64 bytes of RAM with a supportive 128 bytes
EEPROM. It also contains the internal oscillator, a
comparator, an ADC and timers. We can use the USB
3.0 for the PC-bus connection which will help in
attaining a higher rate of data transfer of about 5Gb/s
which is 10 times much more faster than the USB 2.0.
The USB 3.0 will help to form or generate a PC-based
Oscilloscope with high data transfer rate, higher
resolution, higher memory than the other oscilloscope.
The cost of the PC-based oscilloscope using PIC
12F675 is also low, so it is also cost efficient. Therefore,
our main aspect is to make an improved version of the
oscilloscope using PIC 12F675 IC.
Keywords - Digital Oscilloscope, PC-based
Oscilloscope, PIC 12F675, Visual Basic 6.0, Micro-C
Pro.
ISSN: 2231-5381
I.
INTRODUCTION
The oscilloscope, or we can say scope in short,
is a device used for drawing the graphs of the voltage vs
time. The oscilloscope draw these graphs very quickly
and easily. Such type of the instrument is clearly useful
for the purpose of the design and the repairing of the
circuits in which the value of the voltage and current
changes with time. As we know that there are many
other devices such as transducer, which is used to
convert the non-electrical quantity like pressure, light
intensity and sound into the electrical quantity or
voltage. By employing a transducer the oscilloscope can
draw the plot of the changes occurred in any measurable
quantity. This capableness of the scope is used in the
science and technology.
The affection of the oscilloscope is the cathode
ray tube or in short CRT. Looking at the front panel of
the instrument, we are viewing the screen section of the
CRO on which the beam of electrons strikes to generate
the trace. Electronic circuits used in the oscilloscope
employ voltage on one of set of the deflection plates to
sweep the beam of electrons around the screen from left
to right at a fixed rate on the time axis. Other component
of the CRO magnify or faded the input signal as
required, and then apply this voltage signal to the other
set of the deflection plates to provide the vertical
movement to the signal. To calibrate time and voltage
scale the controls are furnished to imply any given
situation.
At the closing of the each reading the beam of
the electrons is brought in off and the horizontal
deflection of the voltage is readjust to again start the
beam at the left border of the screen. Since the
oscilloscope is generally utilized to plot a quickly
changing measures so the plot of these signal may end in
few microseconds. When we will repeat the
phenomenon of taking the readings again and again, we
can repeat these sequences so that we can get a suitable
trace of the examined signal. In the oscilloscope, a
circuit called trigger circuit, is used to analyses of the
incoming voltage signal and then put the beam of
electrons at the initial point for the repetition of values
of the different-different data. The result of input signal
available on the screen. In the oscilloscope various
controls are offered to the trigger values as required for
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International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
experiment. The oscilloscope we use has two channels
to plot the two different voltages so that we can compare
the signals.
At the left side of the instrument, the CRT
screen is divided into a one centimeter grid, ruled on the
inside surface of the tube. On the screen the solid lines
provided for determining the vertical and the horizontal
deflection of the signal and the dotted lines are given for
analyses or measure the pulse rise-time. When we will
move along the panel, there will be a power switch and
the CRT controls through which we can control the CRT
functions such as its intensity, focus, etc. When we will
control the intensity of signal on the CRT to provide a
visible trace than the excessive brightness of the signal
will lead to defocus the spot and can harm the screen.
Both of the focus and intensity should be needed to be
set when the value of the signal changes in forceful
manner. Now the position controls are used to centralize
the spot on the CRT, and then the beam finder button is
freed to obtain a suitable display for final adaptation.
II.
WORKING PRINCIPLE
Here we are working on PC-based Oscilloscope
that have two channel or we can say dual channel. This
is basically a microcontroller based CRO that operates
on few megahertz frequency. The primary section is the
power supply section that use DC power from any
source of DC power, this power supply is applied to the
shunt capacitor where shunt capacitor is connected to
the 7805 voltage regulator that again connected to the
capacitor. Here the shunt capacitor is used to filter
pulsating DC into the pure DC supply so that it can be
applied to voltage regulator and again the capacitor is
used to remove the any AC component from the
outgoing supply of the regulator (7805).
Next section is microcontroller that is PIC
12F675, which is an 8-Pin, Flash-Based 8-Bit, PIC ®
Mid-Range CMOS µC, which is available in SOIC, 8pin PDIP, DFN and MLF-S packages. One of the
advantage of PIC12F675 over the previous PIC 12F629
is that it has a 10-bit ADC fabricated inside it. In brief,
the features of the PIC12F675 consists of 1024 words of
program memory, an internal oscillator, 64 Bytes of
RAM and 128 Bytes of EEPROM, an ADC, timers, and
a comparator.
The PIC µC will convert analog data to the
digital form and send a serial information of this
converted data to the computer through any standard
serial port (DB9 connector) or USB to serial convertor.
The data will be send with the help of the RS 232 IC
which is serial port data transfer IC. RS-232 is used for
serial data communication or transmission. The RS-232
strictly fixes the connecting signals between a Data
ISSN: 2231-5381
Terminal Equipment (DTE) i.e. computer terminal and a
Data Circuit-terminating Equipment (DCE) i.e. modem.
Once RS-232 serial port was very important
feature of a computer, this feature was used to establish
connections to modems, printers, mice, data storage,
uninterruptible power supplies, and other peripheral
devices. The USB RS-232 plays a very important role in
the modern personal computers. A large number of PC’s
does not have RS-232 port in them so we place an
external USB-to-RS-232converter, which will perform
the working of RS-232. So here we use RS-232 so that
we can connect the Oscilloscope with every computer.
Than the PC software written in Visual Basic
6.0 will communicate with the PC serial ports and
process the data incoming from PC-based Oscilloscope.
After processing the data the software will plot a graph
of the data in its console screen.
III.
BLOCK DIAGRAM
Fig. 1 Showing the block diagram of PC-based
Oscilloscope.
IV.
CIRCUIT DIAGRAM
Fig. 2 Showing the circuit diagram.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
V.
PROGRAMMING DETAILS
The program for PC-based Oscilloscope is
written in the Visual Basic 6.0.
VI.
1.
2.
3.
Trace of Triangular Wave.
RESULT AND DISCUSSION
Trace of sine wave.
Trace of Square Wave.
The first trace is showing the sine wave of
82.8Hz and 3.1V peak to peak value. We can find these
values by moving the reference lines of time period and
amplitude. The second trace is of square wave which is
107.7Hz and 3.2V peak to peak. The third trace is
showing the triangular wave of 82.4Hz and 3.2V peak to
peak. At the bottom of the trace the hex values of the
output is provided through which we can analyses the
output easily. The output values has more accuracy
comparing to the trace of the analog oscilloscope.
VII.
CONCLUSION
This PC-based oscilloscope has various
advantages over the analog CRO’s as it is working on
10-bits ADC so it has higher accuracy to that of the
analog CRO’s. It consist of 1024-words for the program
memory, 128-bytes of data for EEPROM and the 64bytes of data of the RAM, it also consist an internal
oscillator, timers, an ADC and a comparator which will
make the working of PC-based oscilloscope more
efficient. It is also very much cost efficient and also very
easy to operate. We can use it in the labs for several
result and the graphical studies. This oscilloscope can
allow an utmost of 20 thousands samples of a particular
signal. It has very low or negligible maintenance cost.
It has only limitation that it can process signals
in the range of 0V-5V.
[1]
[2]
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VIII.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
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