Hello and welcome to my second instructable, where we'll be modifying a cheap RC car to drive it with an Android smartphone over Bluetooth.
  Actually, this was my school project at the Lycée Jules Fil , so I had to produce a complete write-up. Unfortunately, it is in French, but if you want a really in-depth description of the system, and you understand french, you can download it HERE .

   I recommend that you read my first Instructable  for a more detailed explanation on how the thing works.

  The cost of following this instructable is something around 30~40$ if you already have the RC car.

  Disclaimer : In this instructable, you will be using dangerous chemicals (Acetone and Ferric Chloride) and dangerous tools (drill, saw, soldering iron,etc...). I can't be held responsible if you harm yourself following this guide. If you follow this instructable carefully, and protect yourself you won't get hurt.

  So, the RC car will be driven using the accelerometer sensor (like in iPhone/Android racing games) over bluetooth. For that, we'll be using an android app and arduino library named Amarino 2.0 . The system works a little bit like that : 

           |     I²C
          \ /
Android Smartphone
           |     Bluetooth
          \ /
          |     PWM / simple logic
         \ /
         \ /
Rear motor + Dir motor

Dont forget : If you liked my Instructable, please rate it , and let me know in the comments what you think about this Instructable, and what I could do to make it better ! Thanks !

Below is a little video demo :
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AhmedE141 month ago

what a great project , It worked well until I changed the name and password of the bluetooth module (AT command mode) as the arduino stopped receiving data from the bluetooth module , Can anyone tell me why did this happen?

a1r (author)  AhmedE141 month ago
You have to delete the device from you list of paired devices on your phone and redo the pairing process. Afterwards you can add it back in the Amarino app.

why we need to be a pro, to download the project pdf

why we need to be a pro, to download the project pdf

why we need to be a pro, to download the project pdf

b.darawshi3 months ago

good work :) ,,,,,,, can you explain why you multiply value by 24 in this line

intdata[0] * 24

a1r (author)  b.darawshi3 months ago
This value has a max of 10, so I amplify it by 24 to get a value using the (almost) full PWM range (0-255)
意金1 year ago
Hello ^ ^). May I ask a question about the schematic of the DIY PCB. Based on the schematic of IC L293 given, the Pin 8 and Pin 16 are VSS. But they connect the Pin 5V of Arduino and "+" of the 9V battery. Is that all right to connect to a different voltage(5V and 9V) in an IC?
nwalawalkar 意金11 months ago

May be, this can be of great help


a1r (author)  意金1 year ago
Nope. Pin 16 is logic supply (goes to arduino 5V), pin 8 is motor supply, goes to 9V
意金 a1r1 year ago
If the Pin 8 is motor supply, goes to 9V, so may I ask is this necessary to Plugin 9V battery to the RC CAR? IN another way, The RC car has power supply itself(2AA Battery), is this still an useful working part? Appreciate~ ^ ^)
意金 意金1 year ago
Thanks. Finally I figured out. The 5V and 3.3V are out put to motor and blue tooth right? Sorry. ^ ^)
nwalawalkar11 months ago


I am using Eagle 6.5 and while printing the mirror text is printed as dots....

Any help?

louie_yo1 year ago
hi! sorry for the noob question (and my english) but does it matter which arduino i use? must it be duemilanove or can i use leonard? thank you!
意金1 year ago
Hi ^ ^)May I ask what is the function of the "jump" on your schematic of the DIY PCB. In my point of view, the RX and TX on Arduino Board is just connected to the DIY PCB board's RX and TX then connects to the RX and TX of blue tooth.
意金1 year ago
Hi, dude~ Excuse me, may I ask where to solder Power switch. Is the same place that the pic showed us? And if consider about the schematic of the DIY PCB, where is the power switch in there? Appreciate~ ^ ^)
意金1 year ago
I have no idea why the pic can't be uploaded. May I ask your email therefore I can send the schematic of the IC L293 to u. That shows the pin of the IC.
意金1 year ago
Hi, a1r. Dude your are awesome! I was doing this as a project of my study. Here is the thing I feel confuse about the PCB schematics that resored by the eagle CAD. If the positive"+" to the 9v, is the negative"-" to the GND or GND 1?
The 9v battery power supply the power to the DIY PCB with L293IC, and the Arduino board, Bluetooth kit are supported by the extra power supply to the blue Arduino board, is that correct? Appreciate your help~ ^ ^
a1r (author)  意金1 year ago
The "-" of the battery goes to one of the two big GND pads next to the L293 and you have to connect the other big GND pad to the Arduino's GND pin (the same one with the blue wire and socket).
意金 a1r1 year ago
So u mean, 2 GND pads near L293, one is connected to "-" of 9v battery and another one is connected to Arduino GND pin, and the big GND pad is also connect to the BT kit's GND am I correct?
a1r (author)  意金1 year ago
意金 a1r1 year ago
Thank you thank you~ ^ ^
意金1 year ago
Thank you thank you~ I connect BT kit directly to the Arduino board just for testing my BT kit see if it is working or not (return policy^ ^)
Sry I still can't get "the BT GND pad connects to a GND pad (near the L293 for example) through two wires connected by a 2-pin connector",
I know BT GND to GND on the PCB near L293, but why throught 2 wires? there is only one wire (the yellow wire in the pic).
Do u mean the 2 pin connector is connected to 16 pin DIP socket?
Simply it is like I don't know where dose the 2 pin connector(yellow wire in the pic) plug in?
sorry~ I don;t speak English much, Appreciate for your patient~ ^ ^) dude
意金1 year ago
Hi wts up dude ^ ^ , so can I say GND is connected to "-"of the 9v battery, and GND1 connects to GND of the Arduino board, and the GND of bluetooth is connected with the 2 port GND came with the Arduino board. Am I correct?
Beside I see the bluetooth has a 2 head plugin connected to GND of the Arduino board, so for the buletooth kit, can I ask do we have to use 2 head plugin to full plug into the 2 ports GND of the Arduino board?
the following images are 2 ports of GND, and 2 heads of the GND plugin which is from the bluetooth, I mean. ^ ^) Appreciate~~
a1r (author)  意金1 year ago
Aaah. You didn't understand correctly: The PCB you made sits ON TOP of the Arduino and utilizes ALL of the Arduino pins (you can't plug something else in them), that's the concept of an Arduino shield.

And the BT GND pad connects to a GND pad (near the L293 for example) through two wires connected by a 2-pin connector (your second photo) like this:
BT GND---------==- ==---------GND pad on the pcb

I did this to be able to shut down the BT module by unplugging this connector: when I uploaded a new sketch, the BT module would cause the upload to fail, so I had to switch it off during that time.

Be sure to look closely to the photos I included in this instructable, they explain pretty much everything (correct wiring and stuff)
意金1 year ago
Thanks thanks~
I find both Dir motor and rear motor have 2 wires. Is there any "+" or "-"or other differences between the 2 wires either from the RC car circuit board or any differences between the 2pads of "Dir moto" or "moto" on DIY circuit board? (in the PCB schematic they are M1,M2.D1,D2, so is there any main difference between M1,M2,or D1,D2?)
For those 2 image, I just directly connect the 2 wire either from the Dir motor or rear motor to the DIY circuit board. Is that correct? Thanks~
And may I ask is it possible to connect the Dir motor and rear motor directly to the Arduino Board...Appreciate~ ^ ^)
a1r (author)  意金1 year ago
Technically, nope no differences, BUT I've written the software so that the DIR pins are meant to be connected to the Direction motor and the Motor pins have to be connected to the Rear motor.

One last thing: if your car turns in the opposite direction, swap the red and black wires soldered to the DIR pins. If the car goes reverse when you tilt your phone forward, swap the red and black wires soldered to the Motor pins.
Amazing thing I'm looking first time android Rc car thanks for the post keep sharing this kind of information.
For everybody with arduino IDE versions higher then 1.0: download the two files in the link below and replace the MeetAndroid.cpp and MeetAndroid.h in the library folder of the Arduino IDE with the new files. Then your code should work. Go to this link: and download the two files named "MeetAndroid.cpp" and "MeetAndroid.h".
a1r (author)  Thom Kouwen1 year ago
Thanks buddy :P
kverula1 year ago
i try to change the battery but there is no improvement. When i use the multimeter in the every pin of IC there is no voltage output. so i think there is a problem in the IC.Need help for troubleshooting plz reply ASAP
kverula1 year ago
I already fixed the problem about the program and i already complete the wiring.when i try to pair with my android the output of the rc car is just a beep.why is that?plz help thx
kverula1 year ago
Plz help i have a problem in the program.This is the error

In file included from RCdroid.pde:6:
C:\Users\jonathan\Desktop\installer arduino\Arduino\arduino-1.0.4\libraries\MeetAndroid/MeetAndroid.h:104: error: conflicting return type specified for 'virtual void MeetAndroid::write(uint8_t)'
C:\Users\jonathan\Desktop\installer arduino\Arduino\arduino-1.0.4\hardware\gizduino-\cores\gizduino/Print.h:48: error: overriding 'virtual size_t Print::write(uint8_t)'

i already followed the instructions but i still i encounter this.plz reply ASAP
sunand c s1 year ago
hi please send me the circuit diagram of this project.i am doing exactly the same project
my e-mail id
kverula1 year ago
I have a question, what if there is no stock for arduino duemilanove, what is other alternate arduino?
a1r (author)  kverula1 year ago
You can use the Uno too
iabir1 year ago
i have a there any was to use bluetooth USB adapter instead of bluetooth serial adapter?...if yes then how?
mohdhafiz1 year ago
Jonathan:can i ask u..i know Proportional Speed ..
how to operation..
u can explain
intdata[0] = int(data[0]);
intdata[0] = intdata[0] * 24;
a1r (author)  mohdhafiz1 year ago
Could ya please give me like the 10 lines of codes surrounding this, I can't figure out like that ... thx
mohdhafiz a1r1 year ago
sorry to many question.

void setup() {
Serial.println("\t\t\t| Starting Up.. |");
pinMode(EnablePinDir, OUTPUT);
pinMode(EnablePinMotor, OUTPUT);
pinMode(LogicPin1Dir, OUTPUT);
pinMode(LogicPin2Dir, OUTPUT);
pinMode(LogicPin1Motor, OUTPUT);
pinMode(LogicPin2Motor, OUTPUT);

Serial.println("\t\t\t| PG-R Ready ! |");
Serial.println("\t\t\t| Have Fun ! |");

meetAndroid.registerFunction(floatValues, 'A');
-what the function..Serial.println("\t\t\t");
// ..===========================================..
// || ||
// || Control Algorithm Beginning here ||
// || ||
// ''===========================================''

// This is for Forward/Reverse
if (-10<=data[0]<=10) {
// Tilt-Proportional Speed
intdata[0] = int(data[0]);
intdata[0] = intdata[0] * 24;
-why multiple "24";

a1r (author)  mohdhafiz1 year ago
The serial functions can be disabled, they're just here for debug
The multiply by 24 is here to adapt the data (ranges from -10 to 10) being sent to the motor controller (which gets -240 to 240).
mohdhafiz a1r1 year ago
how to to identify the axis x or axis y in program?
mohdhafiz a1r1 year ago
What effect I remove or not use Serial.println?.
-240 to 240 range ??..current or voltan.
I weak in the program,new venture into this field..
mohdhafiz1 year ago
Jonathan:tq,my project success..from help of you
a1r (author)  mohdhafiz1 year ago
Your welcome
jonathan thank you for your help? RC CAR dpat now I walk, it turns BT modules are problematic and I replaced it with a new one.
but? there is still a problem if the wheel goes forward, backward, left and right making a sound "BEEP"??
Why is that?? Is there something slah with my chip? but I have replaced it with the new still reads "BEEP"?
asmuransyah:powerful enough,try battery change...,or.r_gc.r_pw.r_qf.&bvm=bv.42768644,d.bmk&biw=1241&bih=640&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=iCQpUZ2FA9GGrAe4koEY#um=1&hl=en&tbm=isch&sa=1&q=+nicad%2Fnimh+pack+&oq=+nicad%2Fnimh+pack+&gs_l=img.3...18648.22262.4.22668.,or.r_gc.r_pw.r_qf.&bvm=bv.42768644,d.bmk&fp=5d827613dcf2ae72&biw=1241&bih=640&
maniza22041 year ago
im having problem with the programmed, could u plez help me ?
it says :
C:\Users\LaPtOp PuNoH\Desktop\mat\arduino-1.0\libraries\MeetAndroid/MeetAndroid.h:104: error: conflicting return type specified for 'virtual void MeetAndroid::write(uint8_t)'
C:\Users\LaPtOp PuNoH\Desktop\mat\arduino-1.0\hardware\arduino\cores\arduino/Print.h:48: error: overriding 'virtual size_t Print::write(uint8_t)

maniza2204 :read intruction correctly..
u must insert one libray android to sofware Arduino...
- Download the Amarino Arduino Library
- Extract it in your libraries folder : arduino_install_dir/libraries/extract_meetandroid.zip_here

asmuransyah:i see connect false..Motor d1 and motor d2,must connect parallel..
if you more disconcerted, check the circuit using circuit draw ..

Jonathan:I hope the tech is correct, if there are errors please show
a1r (author)  mohdhafiz1 year ago
Hum, you're right, you do have to install the library. BUT for asmuransyah's wiring, it IS in fact CORRECT: First of all the Init sequence does run, and secondly, I can't find any flaws by looking at his photos.

The issue comes from the BT module: either it's a 5V module and he should remove the resistor divider (ONLY if it's a 5V module), either he's using a different baud rate (I really think this is the problem).
if init is the source sketch?? I do not know where init is???
please help me ... I really need your help???
a1r (author)  asmuransyah1 year ago
Dude, if your car goes forward backward left then right, that means that the init sequence works just fine, and that you have nothing to worry about concerning your soldering job. BUT can you just give me the link where you bought the bt module ? If you don't, then I can't help you anymore.
a1r (author)  a1r1 year ago
Oh and yeah, his soldering is also pretty messy and unfinished (i.e. he didn't heat the pads long enough) : that equals to poor signal transmission, it could also be an issue.
so?? do i have to reset again for my car to be good in soldering ...
My RC CAR after me upload arduino sketch in arduino wheels front move left and right, for wheels back move forward and backward. But if me remote from smart phone cannot respond RC CAR.........
a1r (author)  asmuransyah1 year ago
If the init sequence completes, then the Arduino/soldering part is done right --> the problem comes from the bt module: try to find a link to the datasheet/product page so I can have a look at it. Does the application successfully connects to the bt module?
Jonathan this my RC Car picture, please help me check wahts wrong this my RC car
a1r (author) 1 year ago
modhafiz: It seems either your chip is dead (i doubt that), or, more likely, your battery isn't powerful enough: try to use a nicad/nimh pack (7.4V or more) in place of the 9V battery.

asmuransyah: I'm gonna need more info: does the car make the init sequence or not (first, check that the init isn't commented in the Arduino code). Does it complete the full sequence (all directions) or reset before that? Again, there's a good chance that your 9V batt isn't powerful enough: use NiCad/NiMh.
jonathan i have check all the soldering? all seemingly well on the multimeter ... so what should I do to be able to make in the remote RC ...??
mohdhafiz1 year ago
Jonathan.I'm getting "beep" sounds,motor forward..
why motor not running..
hi mohdhafiz may i look u RC car?? can u upload u picture RC CAR...
mohdhafiz1 year ago
i double check solderimg using multimeter,it negligent...
i use ic l293d. and change l293b..same not respond motor...
Jonathan.?.thank you for guild me..
mohdhafiz1 year ago
Jonathan..i have the same problem as asmuransyah ..
data sent from my phone .rc car not respond..u can guild me?
a1r (author)  mohdhafiz1 year ago
Triple-check each step to make sure you have soldered everything right, and use a multimeter (in continuity tester "buzzer" mode) to check EVERY solder joint and while you're at it check the pcb too. When you are done, and if it still doesn't work, I'll try to help
mohdhafiz1 year ago
Jonathan..i have the same problem as asmuransyah ..
data sent from my phone .rc car not respond..u can guild me?
Jonathan?? i make the RC Car android with follow you instruction, but my phone cannot respond mobile RC CAr dan cannot remote. so how me make the phohe work and can remote the mobil...
a1r (author)  asmuransyah1 year ago
Try to use an older version of arduino, like 0027 or something older. BTW, did you read ALL the comments, for a problem resembling yours that could have been already solved? Just sayin'
y??? i had reade all comment but not 1 give me guid me for my TC car??? can u help me??
Jonathan?? i make the RC Car android with follow you instruction, but my phone cannot respond mobile RC CAr dan cannot remote. so how me make the phohe work and can remote the mobil...
mohdhafiz2 years ago
hello..i follow to step intruction..
1.Gnd connect to (-)battery,other one Gnd1,what is to connect?.
2.why my bluetooth not detect use Battery,i try connect use USB to arduino.bluelooth can detect my Fon bluetooth,,,
and after device connect my fon,motor not running...
Please tell me sooner if this type of conection works :D
Thank you for your amazing post !
mohdhafiz2 years ago
what function use power sw,
can change switch push button?...
asmuransyah2 years ago
Hai jonathan richo?? can give me you paper anroid rc in english language.... you can send the paper at my e-mail please give me jonathan i need tou paper??
asmuransyah2 years ago
hi?? can i using blutooth DFRobot Bluetooth V3 and arduino uno for Android RC Car....
arun.dh932 years ago
Its a great step by step tutorial.
You have used arduino here.Can we use avr? I use atmega 32 for all my projects so how do i do it? Is there any library for that?
techboy4112 years ago
Can it work with my iPhone 3Gs?
techboy4112 years ago
Can it work with my iPhone 3Gs?
koko4622 years ago
as I walk to the arduino with 9v and 12v pcb. to walk strong engines
safire0072 years ago
hello there my phone is detecting the bluetooth module but when i turn on the accelerometer sensor the motors wont move.i use sony xperia arc s phone.
mohdhafiz2 years ago
can u upload full draw circuit..
i hope u can help me,
i want make this project,,,
mohdhafiz2 years ago
Hello,u can upload to programs IC..
pls or mail box me
koko46252 years ago
You could send me an email I send my doubts haci if not too much trouble. my email is
fckingdavai2 years ago
An Arduino Duemilanove with BlueTooth integrated will work fine for this application? instead of using an arduino duemilanove and a separate bluetooth adapter?
a1r (author)  fckingdavai2 years ago
koko46252 years ago
Hi, I'm new at this. my question is I can replace the Arduino Duemilanove by Arduino Mega 2560? something affects me or not?
jm1312 years ago
sir I also want to make one of this. can you pls give me the program codes for the accelerometer? and also the codes you used in the arduino and eagle cad? if yes you can send it to my email and pls confirm..l thanks...
Mr Jonathan i have problem seeing the bluetooth module in my fone, can you please guide me in this one? all is properly connected as well as the 9v battery :(
asmuransyah2 years ago
Hallo mr. Jonathan Rico can i make you project for my My college thesis.....
I am interested in your work, and I wanted to make my final ... I hope you allow me to make it as my final project.
a1r (author)  asmuransyah2 years ago
Of course, no problem !
asmuransyah a1r2 years ago
thanks mr.jonathan Rico......
which bluetooth module should i use ??
can any1 plz give the exact specifications ??
can i use l293d motor controler
dude, can i solder the wires like this:
1.Conect arduino and vin pin to the motor controllers pin 16 or 9v pad
2.Than i conect both gnd pads with jumper wire and conect them all to gnd pad of the arduino and shield
3.Than than the motors (that's clear) thanks :)
4.As a power source i conect the arduino with 9 volt battery, clip, and male conector that fits on the arduino, and switch.
Please tell me sooner if this type of conection works :D
Thank you for your amazing post !
a1r (author)  evilcomputer2 years ago
Yup, but you'll very likely have a brown-out: the 9v battery can't supply enough juice for both the motors and the arduino, and the arduino will reset, closing the bluetooth connection. It's bettery to use a NiCad or NiMh or even LiPoly battery if you can find one that's >7volts
can i use 6v acu battery :D
dude can you tell me if this project works with this bt module and how do i conect it
syanikog2 years ago
Hey I got the car working twice with this tutorial. I then tried to rewire it and have not been able to get it working again. I replaced the fresh 9v battery with a rechargeable one. Is there any chance I burned out my L293E by putting it in wrong? i imagine putting it in backward wouldn't change much, just switching from 9V to 5V right? I also tried putting my bluesmirf module on 5V instead of 3v3 as well as grounding through the battery and arduino board and didn't find anything different. Do you know any simple ways to test my L293E? I think my phone is connecting and sending a signal (I just tested it with a servo).
Harsh2982 years ago
can i use ATMega168 (Based on Arduino Diecimila) pls reply me fast
a1r (author)  Harsh2982 years ago
mmitkovski2 years ago
Why I'm getting "beep" sounds ?
a1r (author)  mmitkovski2 years ago
The sound is coming from the motors
mmitkovski a1r2 years ago
Yes, but why ?
a1r (author)  mmitkovski2 years ago
The arduino IC generates a PWM pulse that is amplified by the motor driver (the IC on the shield) and then fed into the motor. Since the pwm frquency is in our hearing range (490Hz), the magnets and the coil in the motor act like a speaker, that's why your motors are buzzing.
mmitkovski2 years ago
How to put IC ? What is the correct position, which side to be up, which down ? Thanks
Real_Neo2 years ago
I'm getting a compile error with your code

"In file included from RCdroid.cpp:6:
C:\Arduino\arduino IDE\libraries\MeetAndroid/MeetAndroid.h:104: error: conflicting return type specified for 'virtual void MeetAndroid::write(uint8_t)'
C:\Arduino\arduino IDE\hardware\arduino\cores\arduino/Print.h:48: error: overriding 'virtual size_t Print::write(uint8_t)'

Is it possible that they updated the Print.h library recently?
I found a solution, had to change the write function's return type in the MeetAndroid library. Also, with Arduino IDE 1.0 they changed some library names, so they should be updated in the MeetAndroid version you have posted here.
bjpayton043 years ago
Wanting to do this project but Im running into some problems. I have a Samsung Captivate(ATT) and I cant seem to connect my bluesmirf to my phone. I am able to pair but not connect. Another question, does anyone know how far the Bluesmirf gold will allow you to go? Im doing this as a project/gift and for the project part I was told that my phone needs to be able to shutdown the rc car when it is out of range? Help please! I have less than a month to do such a project. Thanks in advance
Also, with my android it will not allow me to download Amarino to my cellphone it only allows apps from the Android market. Any ideas as to how I can get this toolkit on my phone?
a1r (author)  bjpayton043 years ago
Hum. We have two problems. The first one is easy to overcome, the other is tougher.

- For the "auto shutdown" feature, you have to implement a 'time control' loop. If the time since the last accelerometer info was received is too high, make the car stop. This is implemented on the Arduino side. (hint : use the millis() arduino function). First, try to implement this on your own, and if you're really having a tough time doing this (read: more than an hour of struggling), post another comment, and I'll post the updated code.

- For your AT&T captivate, I shall say one thing : welcome to the wonderful world of CyanogenMod ! This is an optimized android os (read: runs MUCH faster) that replaces your current Android OS. After doing this, you'll have A LOT more control of your phone, and will be able to sideload apps (install .apk files from your sd card, enabling you to install the amarino application), and will also be able to connect to the BlueSMIRF Gold.
Read THIS first and then get the actual CyanogenMod HERE.

- You can expect 10+ meters of distance with your bluesmirf.

bjpayton04 a1r3 years ago
Well Ive tried for more than an hour or so to get the time control loop to work. I worked on it over the past two days. Could you show me the updated code and I will use it to try and write one myself. Thanks ARI
a1r (author)  bjpayton043 years ago
Ok, here's the updated code. I've commented out the lines that you have to pay attention to (right after the rc algorithm's start). As I gave my RC car to a friend of mine, could you please test that code on yours, and post back the results ?
Oh, and, I've set the delay to a reasonable 1second, so keep moving your phone ever so slightly to make sure the car doesn't suddenly stop.

a1r (author)  a1r3 years ago
Oh, I forgot, did you success in flashing your phone with a custom ROM ?
bjpayton04 a1r3 years ago
Is that code you sent me written to support the bluesmirf? Had a little difficulty when I loaded it.
a1r (author)  bjpayton043 years ago
Nope. I only understood that you had problems implementing the "stop car if signal lost" function. This function is the only thing that I've added to the code. What problems are you experiencing with the Bluesmirf, could you please be a little more precise ?
bjpayton04 a1r3 years ago
It uploaded fine to my arduino, but I had trouble with sending signals from the phone. Will try to fix it though. And let you know how it works out. I have one last question concerning this project. Making a battery pack has never been something Ive excelled at. did you use a voltage regulator to run your rc car?
a1r (author)  bjpayton043 years ago
Nope. But after many, many brownouts (the arduino shutting down because the motors were draining too much power from the 9v batt, causing a voltage drop and resetting the Arduino), I really wish I had used a battery pack.

If you're lazy,  This battery pack has a 5v regulator built-in, outputs 800mA (which is plenty for the motor + arduino), and has an usb charger built-in. It is a bit bulky for a small RC car, but I recommend that you buy one, instead of using a 9v batt.

If you know soldering basics, and that you want to build a good battery pack (the size of 2 AAs), I recommend this guide. This DIY Lithium pack will output 7.4v at a high output current (more than 2amps), plus, it costs less than 8$. You can get a charger for this pack here. I will be updating this instructable by adding a step to assemble this battery.

bjpayton04 a1r3 years ago
I hate to bother you but I have been running into this problem. I downloaded the Amarino toolkit to my tablet and when I try to add an event it crashes, did this with my phone also. Did you encounter this problem? Thanks
a1r (author)  bjpayton043 years ago
No. I think this problem is caused by your android version. It is reported problems with some samsung devices (in stock ROM) and htc devices (running htc sense). Try to flash another rom.
bjpayton04 a1r3 years ago
I tried it with my toshiba tablet. It runs 3.1 version
a1r (author)  bjpayton043 years ago
Uh. I dont know if the amarino apk I gave you is optimized for honeycomb. Maybe try to contact the amarino developer.
bjpayton04 a1r3 years ago
Got my board working. However when I upload the program it does not recognize that the signals should come from my phone. Instead it goes backwards, forwards, and the wheels go left right. Im connected to the bluetooth however it is not receiving signals from my phone. Help please :-(
a1r (author)  bjpayton043 years ago
Could you post a youtube video, I think i know what the problem is.
bjpayton04 a1r3 years ago
Not yet..spoke with ATT they supposedly released an OTA update that allows downloads from an open source...using someone else phone at the moment...I will know tomorrow if it works if not I'm trying your method.
bjpayton043 years ago
The code I wrote would not work properly with my project. I used your code to for my project and it worked to a certain extinct. The car tries to go forward, however, I have trouble with the left and right control. Could you help.
a1r (author)  bjpayton043 years ago
Yeah, I can help. But I need more info: post your code on, and also, It would help me a lot if you could shoot a quick vid and upload it to youtube.
francisroan3 years ago
sorry i still didnt read the instructable before asking so no need to reply!
francisroan3 years ago
what is the D1 D2 M1 M2 in the schematic?
a1r (author)  francisroan3 years ago
In the arduino code, that is :
They connect to the control terminals on the L293 chip, and are used to tell the motors (or solenoid) in which direction move. The EnablePin is to set the motor's speed.
francisroan3 years ago
can u give me the schematics?? all the wiring coz im not gonna make a pcb... ill try it out on a breadboard so pls??
a1r (author)  francisroan3 years ago
It seems you still didn't read the instructable ! The schematic is in the zip that you download on step 2. It's extension is .sch, and you have to open it with Eagle CAD (see step 1).
francisroan a1r3 years ago
sorry (again but i was downloading it while i was typing it ... my mistake ...and thanks ...coz ur the one and only person who replies to my every need all other people would just not reply ...(because i ask a lot of questions!!!as u can see) ur a nice guy ( take it as a comliment) i respect u and i hope i can ask any more questionssssss????????????? THANK U!!!11
Amir.Cekic3 years ago
Ur Car is great but Can u tell how to connect the solenoid to the Arduino and How to connect the DC motor to the arduino. Tell me where to put the cables and what kind of wires do i need plz hhelppp me
and if i downlaod the PDF does it tell me Step by step how to make the RC car
techboy4113 years ago
Do you need an app or BT to use this
This is a a great step-by-step!

If you decide to solder this type of Bluetooth module in this way, be very careful, and use flux! I've broken a couple of modules using this method. The connections on the side of the module are fragile, and if the wires are pulled in any way, the connections on the board are likely to break off. I ruined one module/board just by putting too much heat on the terminals while soldering and they fell off. Since I didn't use flux, the solder was refusing to stick, and it forced me to apply to much heat. On another board I was able to get the wires soldered, but then the power wire broke with some very light touches, and the exposed copper terminal came with it.

It might be better to create a footprint for this module on the board that we etched in earlier steps. Then we could place the module on our etched board and just drop solder on the terminals that are needed. It's obvious why the author didn't choose this approach. Doing so would make this Instructable less-usable, because the Eagle file would have this board's footprint on it, and that would mean users would have to purchase the exact same module (which might be difficult to acquire, or out of production).

In conclusion, if you solder the wires to this type of module as shown in the photo, be very careful both during and after soldering, and use flux to get the solder to bond efficiently!
vnovachki3 years ago
Where are used input pins from Arduino (D8,D9,D11,D12) ? I can see that they are connected with input of IC , but are they used (at Arduino code, or anywhere) ? Thank you!
a1r (author)  vnovachki3 years ago
Yup, they're used in the Arduino code, you're right. In fact the H-Bridge (the IC used to drive the motors) needs more info than just a PWM pin. It has to know in which direction the motor has to be running, and these 4 pins (the H-Bridge is in fact, 4 half bridges) are just that info. (PS: All the juicy details here)
mmitkovski3 years ago
Can I use this tutorial to build a helicopter? Or that toy has a more motors? Thanks
a1r (author)  mmitkovski3 years ago
Uh, yeah, maybe, you could but it would be kinda hard. Controlling an helicopter is a bit trickiest than controlling an RC car. It's just not the same thing. You can have a look at my new instructable (which is talking about an heli). If you manage to get it working, let me know !
Omer Faruk3 years ago

I have got a term project look like this project. But I need all source codes this project because i want study on that codes. Please can you send me all source codes??

a1r (author)  Omer Faruk3 years ago
Man, look better : the Arduino sources are in Step 11 . BTW, If you want the sources of the Android application, look at the developer's website or the google code page.
godspeed7x73 years ago
Very nice man!!!Proved very helpful to me just one question about the bluetooth module used,Can i just hack open a USB bluetooth dongle and use the module inside it for this instructable???which pins of the USB will be the 3.3V ,ground ,TX and RX???Please answer fast ,i'm ,i'm in a hurry for my school sicience fair!!!Thankyou!!!
a1r (author)  godspeed7x73 years ago
Uh, sorry I thought I had answered you before, but it seems that the answer wasn't published :(
You can't just hack open an usb bluetooth dongle to use the module inside, 'cause the usb protocol is kinda heavy for the little arduino. Again, sry for not answering before.
Mutantflame3 years ago
This looks fun! Unfortunate that I have an iPhone and not an android device in this case. I wish I could make it.

By the way, I was the three thousandth, three hundredth and thirty third person to view this. What a lot of 3s!
a1r (author)  Mutantflame3 years ago
Then funniest thing is that, in the very beginning, the project was supposed to use an ipod touch as controller :D  Back then (in March 2011), the BtStack project didn't have support to establish an RFCOMM connection to the arduino's bt module. So I decided to switch to Android, I sold my ipod and bought a moto Defy.
But don't lose hope : check out the iDroid project. If you have a iPhone 2G or and iPhone 3G, you can dualboot android on your iPhone.
Good luck !
mmitkovski3 years ago
Hi, I'm interesting to make this project. Is it ok to buy this board or maby I need deferent model ?

a1r (author)  mmitkovski3 years ago
Yup, you can use that board, no problem !
mmitkovski a1r3 years ago
Thank you , this project is excellent :) Also I want to know why the IC is soldered of the opposite side of the pcb ?
Thanks again .
a1r (author)  mmitkovski3 years ago
Thanks ! Regarding the IC, I was obliged to solder it on the opposite side of the shield, as the atmega IC on the arduino was taking all the space on the other side.
tank10003 years ago
couldn't this be done with the arduino BT insted of making a shield?
a1r (author)  tank10003 years ago
Of course. But you'll still need some component to drive the motors 'cause the arduino can't output enough current to control motors by himself. If you're using an arduino bt, just skip the steps related to the bt module. See my previous instructable for more info.
tank1000 a1r3 years ago
you could just build the shild and then power it with the same amount of power that the arduino gives
a1r (author)  tank10003 years ago
If you're problem is making the shield, and you already have an arduino bt, you could just buy a motor driver shield like this one :
tank1000 a1r3 years ago
My problem isn`t making the shield i just have a small car where the shield won´t fit in unless i use the BT or get the shieled to work with an arduino nano if possible.
a1r (author)  tank10003 years ago
Uh, ok. Well I have the same problem (I just took off the car windows, the arduino+shield combo was just sticking out of the car), and yes the shield could be adaptable to an arduino nano, as I've included the schematic in the eagle project zip (see step 2), you only have to rearrange the pcb layout. Good luck, man !
tank1000 a1r3 years ago
Thanks! i´ll post pictures when i´m done with my own car
stavros0153 years ago
Men thats crazy i like it and i'm gonna make it
a1r (author)  stavros0153 years ago