I upgraded my remote controlled car from a drive-by-wire system and added Bluetooth control with an iPhone/iPad. The Bluefruit LE Connect for iOS can be downloaded from the app store. After connecting to the device, select Controller > Control Pad.
The Adafruit tutorial was extremely helpful for setting up the nRF8001 Bluetooth module. The tutorial also contains detailed information of all the pinouts.
First, I soldered the pins to the nRF8001 Bluetooth Module. I then connected the Bluetooth module to a pre-soldered shield that could be combined with a small breadboard.
I tested the Bluetooth with the the echoDemo example code that came with the Adafruit nRF8001 Arduino library. Although the Arduino serial monitor says that the the Bluetooth device was being broadcasted, I was unable to connect to the device on the app. Turns out the pre-soldered shield was defective. After transferring the Bluetooth module and wiring to a separate breadboard, everything worked as it should.
In the wiring diagram below, the blue wires are hardwired for the Bluetooth module, while the yellow and green wire can be connected to any pin.
In the picture above, the car is powered by a rechargeable battery pack. I found that the wheels wouldn't move when the Arduino is connected to a 9V battery, but would function as it should when powered by a USB connection (to a laptop or battery pack). The rechargeable battery pack is very convenient and saves you from having to buy new batteries.
I noticed that one of the wheels tends to spin faster than the other, causing the car to curve when directed forwards. The fix this, I changed the speed of the motors for each wheel in the Arduino code to compensate for the difference. I also moved the battery pack of 4 AA batteries over the motors to increase traction and control.
I built a small obstacle course and tested out the upgraded Bluetooth controlled vehicle. Now that it is no longer constrained by a remote control leash, I am able to drive the vehicle from a longer distance and not have to worry about the leash getting tangled on surrounding objects. Lots of fun! Check out my video below.