This is the code and simple circuit diagram for a wifi-enabled remote control car driven by an Arduino Uno + Arduino WiFi Shield. The base for our car is a toy RC car called the B-Furious, which is driven by one DC motor and can move forwards or backwards, but cannot turn left or right.
The motor driver circuit and code work effectively, but we could not make the wifi shield work consistently enough to drive the car.
We adapted our circuit from the Arduino starter kit's 'Zoetrope' project (project #10), which controls a DC motor's direction and speed via buttons and a potentiometer. We left the Arduino's output signals, the H-bridge, and the power supplies in place, but swapped out the buttons and pot for HTTP requests processed by a small server running on the Arduino.
The three blue wires in the schematic below are what carry signals from the Arduino to the motor. The leftmost wire, from Arduino pin #9 to the lower-left pin of the H-bridge, is an on/off switch. The other two wires control the direction: the motor turns forward if the left one is HIGH and the right one is LOW and vice-versa. The speed is controlled by a parameter passed in the HTTP request.
Note: we used an L293DNE H-bridge, not the LD293D depicted in the schematic.
The most up-to-date version of the code is in CurrentReceiver/CurrentReceiver.ino.
| Function | Action Performed |
|---|---|
setup() |
Runs wifiSetup() and motorSetup() |
wifiSetup() |
Connects to the wireless network |
printWiFiStatus() |
Prints Arduino's IP address and signal strength |
motorSetup() |
Puts the Arduino control pins in output mode |
loop() |
Waits for requests and processes them |
parseClientInput() |
Splits the incoming HTTP GET request into on/off, direction, and speed parameters. |
motorControl() |
Sets the motor's speed and direction |
The car can be controlled via CURL:
curl -G http://<Arduino's-ip-address> <params>
<params> is a string of integers.
- The first integer, 0 or 1, indicates whether the motor is to be turned on or off.
- The second integer, 0 or 1, indicates the motor's direction.
- the third integer, 000 to 255, indicates the motor's speed.
For example,
curl -G http://<ip-address> 11255
sends the car forward at top speed.
curl -G http://<ip-address> 10020
moves the car backward very slowly.
curl -G http://<ip-address> 01255
curl -G http://<ip-address> 00000
curl -G http://<ip-address> 00125
All of the above (and anything else beginning with a zero) turn the motor off.
While our own code and circuit are functional, we were never able to drive our car because of problems with the Arduino's wifi shield. We had to restart everything any time the Arduino disconnected from the wireless network, which happened frequently enough that it rendered the car unusable.
We did experiment with the Spark Core, an alternative microcontroller with built-in wifi. It showed promise, but had its own problems. After a couple of weeks of finicking with the hardware, we decided to drop the project.