Why not control your RC car with smart phone? Smart Racer WiFi is RC receiver replacement, which uses WiFi (or Bluetooth) as communication protocol and your smart phone as remote controller. Just plug it instead of regular receiver, launch the Android (or iOS) app and you are ready to go. As addition feature the device can also drive RC cars lights.

The main features are:

• Control RC car from Android phone or iPhone (Bluetooh version only).
• Control RC servo and ESC
• Control 5 Leds (front, back, reverse and turn signals)
• Drive RC car up to 70m away.
• Drives Brushed and Brushless motors.
• Works with 1:10 and 1:18 models (1:18 is recommended)
• Powered directly from ESC power
• Control using REST API
• Connection lost cut off (RC stops on WiFi disconnection)

Using WiFi API

The WiFi version device provides REST service API for you to build your own controlling applications.

• Connect to MyRC-5646546 wifi with magicpass123 password.
• http://192.168.4.1/lights/0/on - turns right turn lights on
• http://192.168.4.1/lights/0/off - turns right turn lights off
• http://192.168.4.1/lights/1/on - turns left turn lights on
• http://192.168.4.1/lights/1/off - turns left turn lights off
• http://192.168.4.1/lights/2/on - turns front lights on
• http://192.168.4.1/lights/2/off - turns front lights off
• http://192.168.4.1/lights/3/on - turns back lights on
• http://192.168.4.1/lights/3/off - turns back lights off
• http://192.168.4.1/lights/4/on - turns reverse lights on
• http://192.168.4.1/lights/4/off - turns reverse lights off
• http://192.168.4.1/state?servo=steerValue&esc=throttleValue – sets steering (steerValue between 0 and 20000, where 1500 – usually is centre, 1000 – max steer to the left, 2000 – max steer to the right) and throttle (throttleValue between 0 and 20000, where 2000 – usually max forward speed, 1000 – max reverse speed, 1500 – idle speed) values in µs. If this request is not received for 1 sec, the servo and esc are turned off.
• For faster access steering and throttle values could be sent as binary stream to udp socket at 192.168.4.1:9999 address. Each packed should contain 4 bytes where 0-1 bytes – steering and 2-3 bytes – throttle values in little endian format (uint16_t).

Using Bluetooth API

The control board main part is a cc2541 module by Texas Instruments. This module provides 8051 CPU and Bluetooth radio in one package.

The main part of firmware is its Bluetooth Smart GATT table that defines device services and characteristics. So this firmware has one service for controlling a car and this service has several characteristics/attributes:

• 0xacc2 - Steering attribute – the value from 250 to 500, there 335 is centre, 250 is a left turn and 500 is a right turn (and values in the between could be used for precise control, lower and higher values could be used, depending on Servo).
• 0xacc1 - Throttle attribute – the value from 345 to 422, there 400 value keeps motor off, 345 lets it run backward at full speed and 422 lets it run forward at its full speed (the intermediate values could be used for controlling motor speed, make it run a little bit slower or faster, lower and higher values could be used, depending on ESC).
• 0xa101 - Lights attribute – depending on written values, the Bluetooth module turns on/off the specified lights. (16-bit number for controlling each individual light. 0x0001 – first light on, 0x0002 - second light on, 0x0004 third light on, 0x0008 – fourth light on, 0x0010 – fifth light on.)

Connecting receiver:

• Plug Servo connector to S, VCC, GND pins,
• Plug ESC connector to, T, VCC, GND pins.
• Plug lights to connectors on the right side of the board (the leds + lead should go to leftmost pins, the – led lead should go to the right connector.

Using Android/iPhone app:

• Download the Android app from Google Play
• or Download iPhone app from App store
• Use connect button to connect to your RC car (the name initially would be some random number, that could be changed in settings)
• Briefly touch the throttle arrow – that would start sending idle signal to ESC and starts it.
• User arrow or accelerometer to control steering and throttle.

Two hardware versions:

• WiFi version, controllable from Android phone only, provides REST service
• Bluetooth version, controllable from Android phone and iPhone, provides Bluetooth Low Energy service.

Source code and schematics:

• all code is available at the GitHub

PS. RC car and lights wiring are not included with Smart Racer.