This hack illustrates the Wi-Fi robot which is made from a remote control car that can be driven over the internet or with a laptop wirelessly from up to 500m away by strapping a standard Linksys router. It can be driven without line of sight using a live-feed network camera. The brain behind its operation is comprised of an ATmega168 microcontroller and it can honk at people with its horn. The finished product can be seen below along with a video of its operation.

A pretty large RC car is required because of the addition of extra weight from different components such as a network camera, router, heavier batteries, and extra circuits. Every single RC car uses Realtek RX2/TX2 chips or a pin-compatible alternative which makes it easy to interface a microcontroller directly to these pins.

The Linksys WRT54GL router shown in the images below was modified in order to have a 1GB SD Card and 2 serial ports. One of the serial ports id a console port and the other is a TTS/1.

The PIC16F628A microcontroller was used since it provides the smallest footprint board and can be controlled completely over what the code was doing. In comparison, the AVR Butterfly produced an error in the bootloader when the batteries ran low one time during the usage. It corrupted the code and cannot be reprogrammed unless a new bootloader is loaded. A photo of the PIC microcontroller is shown below.

There are about 6 wires in most toy RC cars that go into the steering motor assembly which contains a metallic wiper that moves with the motor and the extra wires are used to relay which position the motor is in. the setup for this wiper circuit differs in each different RC car. The steering circuit is shown below.

Some high-end RC car batteries shown below were used since the project consumes some major battery power. The batteries are rated about 7.2V and each battery takes about 1.5hrs to charge. The batteries are wired in series for about 16V when fully charged. The standard ATX power supply Molex connectors were used to replace all of the RC battery connectors.

The 4 diodes placed in series with the 7812 12V rail powers the 9.6V rail. Less than 2.8V was dropped across the 4 diodes in series to produce 9V for the devices that need less than 12V since a diode takes less than 0.7V to turn ON. All of the devices are on the 9.2V rail because the camera required 9V and the horn wasn’t loud enough when it was tried on the 5V rail. A heatsink was attached to the 12V regulator to compensate the heat. The power arrangement is shown in the below images.

To reset the microcontroller and allow it to download new code, the Freeduino MaxSerial uses serial pin 4-DTR. The MaxSerial resets when the router serial port starts sending data which is not good to happen. A quick hardware modification is required that will basically add a program-locked mode so that new code can’t be uploaded and the microcontroller can’t be reset by the serial port by pulling-up the DTR pin to +9V.

The type of camera used can be seen in the photos below which runs on an ARM processor at 250MHz with 64MB RAM included. Also shown is a cheap buzzer that is connected to the microcontroller which obtains greater voltage and current using a transistor. This adds the fun feature of being able to honk at people.

When all things are put together, only the base of the RC car was used and all decorative and non-functional parts were stripped off. To avoid conductivity issues, plastic nuts and bolts were used for bolting the circuit boards to the sides of the front part of the car while the PIC controller board was bolted securely to the side of the car. A small modification to the mounting hardware that came with the camera was done when the camera was mounted to the front. To allow for routing the wires, a number of holes were drilled as shown in the images below.