This project report describes a mobile operated robot controlled via a mobile phone. The robot receives DTMF tones decoded from buttons pressed on the mobile phone during a call. An MT8870 DTMF decoder chip processes the tones which are sent to a microcontroller to control motors via an L293D motor driver. The system allows remote control of the robot through button presses on a calling mobile phone without a separate receiver. The report provides details on the components, circuit diagram, programming, and PCB layout.
1. PROJECT REPORT
ON
“Mobile Operated Robot”
Submitted By
VISHRAM ANANT (24), JOEL MENDONCA (33),
GLEVITA MENDONSA (34), JAESON NAZARETH (36)
Under The Guidance Of
Prof: ManaliTayade
Department of Electronics & Telecommunication
Xavier Institute Of Engineering, Mahim.
MUMBAI UNIVERSITY, MUMBAI
2012-2013
2. CERTIFICATE
This is to certify that this Project Report entitled
“MOBILE OPERATED ROBOT”
Is satisfactorily completed by
VISHRAM ANANT (24), JOEL MENDONCA (33),
GLEVITA MENDONSA (34), JAESON NAZARETH (36)
Of T.E(E.X.T.C) class as specified in syllabus.
This report represents their bonafide work in year 2012-2013.
Prof. ManaliTayade Prof. SupravaPatnik
(Project Guide) (H.O.D. – EXTC
Department)
Prof. Y.D. Venkatesh (External Examiner)
(Principal)
3. Mobile Operated Robot
Joel Mendonca, GlevitaMendonsa, VishramAnant, Jaeson Nazareth.
Electronics and Telecommunication Engineering
Xavier Institute of Engineering, Mahim.
Abstract--In this project the robot, is controlled by a made by adding 1336Hz and 770Hz to the other end of
mobile phone that makes call to the mobile phone
the mobile.
attached to the robot in the course of the call, if any
button is pressed control corresponding to the
II. BLOCK DIAGRAM
button pressed is heard at the other end of the call.
The Block Diagram for the circuit is shown alongside
This tone is called dual tone multi frequency tome
(DTMF) robot receives this DTMF tone with the where the input IC is MT 8870, the microcontroller
help of phone stacked in the robot . used is Atmega16 and the motor driver IC is L293D.
Keywords--GSM (Global System for Mobile).
I. INTRODUCTION
The received tone is processed by the atmega16
microcontroller with the help of DTMF decoder
MT8870 the decoder decodes the DTMF tone in to its
equivalent binary digit and this binary number is send
to the microcontroller, the microcontroller is pre-
programmed to take a decision for any given input and
outputs its decision to motor drivers in order to drive
the motors in forward or backward motion. The mobile Fig 1. Block Diagram
that makes a call to the mobile phone stacked in the
robot acts as a remote. So this simple robotic project
does not require the construction of receiver and III.CIRCUIT DIAGRAM
transmitter units. DTMF signaling is used for telephone
signaling over the line in the voice frequency band to
the call switching center. The version of DTMF used
for telephone dialing is known as touch tone. DTMF
assigns a specific frequency (consisting of two separate
tones) to each key that it can easily be identified by the
electroniccircuit. The signal generated by the DTMF
encoder is the direct algebraic submission, in real time Fig 2. Circuit of GSM Robot
of the amplitudes of two sine(or cosine) waves of
A. COMPONENTLIST
different frequencies, i.e. pressing will send a tone
R1,R2 100k resistances
4. R3 330k
R4, R5,R6,R7,R8 10k
C1 0.47 micro farad
C2,C3,C5,C6 22pfarad
c4 0.1micro farad
Xtal1 3.57 MHz
Xtal2 12 MHz
S1 Push to ON Switch
B. COMPONENT DESCRIPTION A DTMFTelephoneKeypad
1.)Dual-Tone Multi-Frequency (DTMF)---- It is used
Table 1.DTMFKeypadFrequencies.
for telecommunication signalling over analog telephone
1209 1336Hz 1477 1633
lines in the voice-frequency band between telephone Hz Hz Hz
handsets and other communications devices and the 697 1 2 3 A
switching centre. The version of DTMF used for Hz
telephone tone dialling is known by the 770 4 5 6 B
trademarkedterm Touch-Tone (cancelled March Hz
13,1984), and is standardized by ITU-T 852 7 8 9 C
Recommendation Q.23. It is Hz
alsoknownintheUKasMF4.Othermulti-frequency 941 * 0 # D
Hz
systemsare used for signalling internal to the telephone
network. As a method of in-band signalling, DTMF
tones were also used by cable television broadcasters Table 2. DTMFEventFrequencies
to indicate the start and stop times of localcommercial
insertion points during station breaks for the benefit of Event Low frequency High frequency
cable companies. Until better out-of-band signalling
equipment was developed in the1990s, Bsy Signal 480 620
fast,unacknowledged, and loud DTMF tone sequences
Dial Tone 350 440
could be heard during the commercial breaks of cable
channels in the United States and elsewhere.
Ring Back 440 480
Tone(U.S)
2.) TelephoneKeypad—
Thecontemporarykeypad is l a i d out ina3 x4
grid,although the originalDTMF keypad had an 3.) Tones--
additional column forfournow-defunctmenu selector Theengineershadenvisionedphonesbeingusedtoaccessco
mputers,andsurveyedanumber of
keys.Whenused
companiestoseewhattheywouldneedforthisrole.Thisle
todialatelephonenumber,pressingasinglekeywillpro d tote addition
h of the numbersign
duce apitchconsistingoftwosimultaneous (#,sometimescalledoctothorpeinthiscontext)
puretonesinusoidal frequencies. andasteriskor‟star‟(*)keysaswellasagroupofkeysform
Therowinwhichthekeyappearsdeterminesthe enuselection:A,B,CandD.Inthe
lowfrequency,andthecolumndeterminesthehighfreq end,theletteredkeysweredroppedfrommostphones,an
uency. Forexample,pressingthe keywesultinasound
l
i
r dit was many years before these keys became widely
used for vertical service codes such as *67intheUnited
composed ofboth a 697 and
States and CanadatosuppresscallerID.TheU.S.military
a1209Hztone.Theoriginal keypads had levers alsousedtheletters,relabelled, intheirnowdefunct Auto
i n s i d e ,soeach buttonactivated onphone system.Heretheywere used before diallingthe
twocontacts.Themultipletonesarethereason phone in order to give some calls priority,cutting
forcallingthe systemmultifrequency.These inoverexistingcallsifneedbe.Theideawas
tonesarethendecoded bythe switchingcentre toallowimportanttraffictogetthrough
todeterminewhichkeywaspressed everytime.Thelevels
ofpriorityavailablewereFlashOverride(A),
5. Flash (B),Immediate(C),andPriority What do you'll do? You lend it to your friend Time for
(D),withFlashOverridebeingthe highestpriority. some time, then you let John listen to music on it, then
you let Linda check her e-mails on it, and finally you
C. COMPONENT WORKING let Nancy search on Google. So what did you do? You
allowed each of your friends to share you IPhone for
Figure shows the block diagram and circuit diagram of
the microcontroller- based robot. The important some time. That is, you allowed you IPhone to be
components of this robot are DTMF decoder, shared in time. On the same lines, in GSM, the radio
Microcontroller and motor driver. frequency say 890 MHz is shared by different users in
An MT8870 series DTMF decoder is used here. All time. This means if user A, B, C and D all talk at the
types of the mt8870 series use digital counting same time. You assign the 890 MHz frequency to A for
techniques to detect and decodeall the sixteen DTMF some time and allow him to talk, then you assign 890
tone pairs in to a four bit code output. The built-in-
band to B for some time to speak, then to C , and
dialtone rejection circuit eliminated the need for pre-
filtering. When the input signal given at pin2 (IN-) finally to D, beforecoming back to A. So the process
single ended input configuration is recognized to be continues in a round robin fashion, as long as A, B, C,
effective, the correct four bit decode signal of the and D want to talk. This way many users talk at same
DTMF tone is transferred to Q1 (pin11) through time on the same frequency. This has to be done,
Q4(pin14)outputs. The Atmega16 is a low power, 8 because as we now frequency or Bandwidth is a scarce
bit, CMos microcontroller based on the AVR enhanced resource and is not available in plentiful, so it must be
RISC architecture. It provides the following feature: shared. Now the second principle that GSM uses is
16kb of in system programmable flash memory with
Frequency Division Multiplex. In Frequency Division
read write capabilities, 512bytes of EEPROM, 1KB
SRAM, 32 general purpose input/output lines. 32 Multiplex, users A, B, C and D, all use different
general purpose working registers. All the 32 registers frequency say 890, 900, 910, 920 for their respective
are directly connected to the arithmetic logic unit, communications. A very good example of this is Radio
allowing two independent registers to be accessed in broadcasting. Because all the radio operators like Rad
one signal instruction executed in one clock cycle. The FM, Go FM, and Radio Mirchi want to operate in the
resulting architecture is more code efficient. Outputs same area, they use different frequencies for
from port pins PD0 through PD3 and PD7 of the
communication 91.0FM, 93.5FM, 94.6 FM, 108FM. So
microcontroller are fed to inputs IN1 through IN4 and
to listen to different communications, you have to tune
enable pins (EN1 and EN2) of motor driver L293d
respectively, to drive geared motors. Switch S1 is used in the receiver set to different frequencies. Now, GSM
for manual reset. uses a combination of TDMA and FDMA. This means
that users A and B are not only sharing the channel in
IV. TECHNOLOGY USED time but also frequency. This means that user A is on
A. SOFTWARE USED the channel 890Mhz for 2 seconds, then jumps to
900Mhz channel for the next two seconds, then jumps
1. Schematic designed on Eagle.
2. Circuit board layout prepared on Eagle. to 910Mhz for the next 2 seconds and so on... Thus,
3. C programming. each user is uses a different frequency at different time
slots. This is called Frequency Hopping.
B. GSM TECHNOLOGY
GSM stands for Global System for Mobile V. PCB LAYOUT
Communications. Just like computers, mobile phones Making a PCB is very simple; it does not consume a lot
have evolved over time. There were first generation of time and the results look professional. After reading
mobile phones in the 70's, there are 2nd generation this How-To and watching the step by step video, you
mobile phones in the 80's and 90's, and now there are will be able to make your own PCB in your workshop
3rd generation mobile phones which we call as 3G using just a few inexpensive materials.
phones. So this GSM is called a 2nd generation, or 2G Many people use protoboard and point-to-point wire
communications technology. Now, GSM makes use of everything, but needing multiple copies of the same
two principles. The first called Time division circuit is the reason that forces many away from using
Multiplexing is very simple. Let's say that one of your protoboard. After making your first circuit board, you
friends possesses the new and sleek Apple's IPhone. might not point-to-point wire anything again! For your
Everyone wants to try a hand at your new accessory. first circuit board, one goal is to keep the circuit single
6. sided so you can etch using single sided copper clad. will embed steel into the copper. Clean off the residual
This will allow you to gain some experience before dust with a slightly damp paper towel.
moving on to double-sided. If you need topside traces,
simply run a few jumper wires on the top. There are
many complete circuit layouts you could try like the
Hack a Day design challenge winner.Here is a list of
materials you will need to produce a single-sided board.
With the exception of the copper clad and PCB drills,
everything on this list is easily obtained at your local
store. Materials: Muratic acid, common household
hydrogen peroxide, safety goggles, good quality
magazine pages (cut to 8×11), laser printer, single sided
1 ounce copper clad, a plastic container the board will
fit in, soft plastic brush, clothes iron, lacquer thinner,
rubber gloves, paper towel, tin snips, drill or rotary
tool, PCB drill bits, Scotch Brite scrubbing pad, good
ventilation, 5-gallon plastic pail full of water. Find a hard, very flat, sturdy, heat resistant surface.
Empty the water out of the clothes iron and set the iron
Now, here is how you do it:
on the hottest setting. Allow the iron to get hot.
Print the bottom side layer on a piece of paper from a
high quality magazine. Use one actual page from the
magazine, the thicker and shinier the magazine paper This is both side of a piece of copper clad. Place the
the better, but do not use the cover. You must use a blank side facing down and copper side facing up.
laser printer, not an inkjet. If your printer uses ink Align printing/paper onto copper clad board with the
cartridges and not toner cartridges, it will not work. If printing facing the copper. Do not allow it to move.
you do not have a laser printer, you can work around
this by printing to white paper and using a photocopier
set to the darkest setting to copy the layout to the
magazine paper. If the paper jams in the printer, you
are not using a thick-enough magazine page. Again, do
not use the magazine covers, as they do not work.
Magazine pages are used because they work well, and
they are cheap! The reason they work is because the
paper is very glossy and the toner does not adhere well
to the glossy pages. The printing used on the magazine
page is ink and it does not come off, but toner does.
Toner is actually a plastic polymer, and different toners
may yield varied results. In our experience, a genuine
HP toner cartridge was used with great success; an
Office Max brand yielded poor results. The sole Firmly press the iron onto the back of the magazine
purpose of the toner is the protect the copper below it paper, sandwiching it between the copper clad and the
from etching away, you only want the uncovered areas iron. Pressing hard without moving the iron, hold the
to etch. Next, wash your hands to remove any oils. iron perfectly still for one full minute. Do not move the
Keep handling to a minimum once the pages are printed iron at all during this minute, and push hard, really
and do not touch the laser printing with your fingers; hard!
this could get oils on the printing. Keep pages as flat as
possible. Then, for four more minutes, slowly move the iron
Very carefully, remove the copper clad from the around making sure to put a lot of pressure on the
packaging. Do not touch the copper surface for the paper, but not allowing the paper to slide on the copper.
same reason as above. You can cut the copper clad to When done, let the board fully cool before you move it
size using a tin snip if needed. Use the Scotch Brite at all. This will allow the toner to adhere to the copper
and prevent you from being burned.
scrubbing pad to gently buff the surface (Scotch Brite is
a popular brand of of plastic scrubbing pad meant to Put the board in cold water and let soak for five
emulate steel wool). Do not use steel wool because it minutes. After five minutes, try to peel the wet paper
7. from the board leaving only the toner/print from your DTMF generator with tone depending upon key
laser printer. Only the toner should be left adhering to pressed. DTMF Decoder, i.e., IC CM8870 decodes the
the copper. If the paper does not come off easily, let it received tone & gives binary equivalent of it to the
soak in the water for a while longer. If necessary, rub
microcontroller. The controller is programmed such
with your finger to remove any paper, leaving only the
toner. It‟s ok if there are a few excess paper fibers stuck that appropriate output is given to Motor Driver IC
to the toner. L293D which will drive the two DC Motors connected
If you find not every trace adhered to the copper clad or to it. The concept used for driving is „Differential
it is misaligned, use lacquer thinner and paper towel to Drive‟. So, ultimately the two motors rotate phone.
clean the toner from the copper board and start over. If According to the key pressed on the keypad of the cell
the traces look good then move on. Inspect the traces
carefully, however, because what you see now will be ACKNOWLEDGMENT
your finished product.
It is our privilege to acknowledge with deep sense of
In a well-ventilated area with a fan, add 2-cups
hydrogen peroxide to a plastic container. Gently pour in gratitude to our project guide, Prof. ManaliTayadefor
1-cup Muriatic acid, to create the etching solution. her valuable suggestions and guidance throughout our
Always wear goggles, gloves, and do not inhale the course of study and timely help given to us in the
fumes. Do not use any metal containers, measuring completion of our project.
cups, stainless steel sinks, or tools with this mixture as
this mixture will aggressively etch metal. Acid safety, We are highly obliged to the entire staff of Electronics
think “triple A”, for Always Add the Acid, it‟s and Telecommunication Department for their kind help
whatever is in the container that will end up splashing. and co-operation. We also take this opportunity to
This etching solution, while made with common
thank all my colleagues for offering all possible help.
chemicals, should command respect. It is dangerous to
you and surroundings treat it with respect. Ferric
Chloride is another common etching solution, it is not a REFERENCES
safer solution to use, and both are equally dangerous. 1 Wikipedia-Thefreeencyclopedia
Put the board copper side up in the plastic container 2 http://www.8051projects.info/
filled with etching solution. Use a soft plastic brush to 3 http://www.instructables.com/
gently wipe the board. You will notice the copper begin 4 http://www.alldatasheet.com/
to dissolve. It takes about 3-4 minutes to get all the 5 http://www.datasheet4u.com/
exposed copper dissolved. You just have to watch to 6 http://www.datasheetcatalog.com/
make sure it is gone in all areas between the traces. Do 7 cell phone operated land rover ElectronicsFor
not leave the board in the etching mix for too long as You‟Magazine , Edition (July 2008)
the traces will dissolve under the toner that is protecting 8 “DTMFTester” , „ElectronicsFor
them. Tinning prevents the copper from oxidizing, You‟Magazine , Edition(June2003)
which can make it hard to solder to in the future. If you 9 http://hackaday.com/2008/07/28/how-to-etch-
choose, you can tin all the traces with solder and a a-single-sided-pcb/
soldering iron now. This actually makes drilling much
easier because it helps to center the drill bit. Make sure
to clean off excess flux if you do this. You could use
Tint to chemically plate the copper. Here is a different
tutorial describing its use.Drill all the holes for the
through-hole parts using the correct size PCB drill bit
and rotary tool. Drill large mounting holes with a
normal drill. PCB drill bits are carbide and made to
drill through fiber glass that would quickly dull
standard bits. There are a few very common sizes of
bits and these are often sold in packs. We use .0260″
for IC holes and .0310″ for resistors and caps.Print out
the top side silkscreen layer on magazine paper and
iron this onto the top side, using the same processes as
above. Again, run under water and peel off the paper.
Now you have the component ID‟s on the top side.
VI. CONCLUSION