/wifi_controlled_rc_car

control a cheap RC car over WiFi using HTTP GET commands, sent from a web browser or python file.

Primary LanguagePythonGNU General Public License v3.0GPL-3.0

WiFi controlled RC car

This project offers an easy way to control a cheap RC car over WiFi using HTTP GET commands, sent from a web browser or python file. The implementation provides a convenient solution for vision or Machine Learning applications (ex. reinforcement learning) to test the developed models in the real world, not just in a simulator.

"Drift tin car", cheap RC car with hacked WiFi module esp8266-01

WiFi features

  • mDNS support, the RC car easily can be accessed through local the network: "http://esprccar.local/"
  • button combinations allowed (like forward + turn left)
  • selectable "virtual press" duration

Command set - browser

To list all available features, just access the http://esprccar.local/ location, by default an info page will be returned as plain text. Commands can be composed according to the needs, using the "set" query parameters. After a command was sent, an HTTP response on the processed parameters and values is returned.

Command structure:

http://esprccar.local/set?p0=1&duration=1000&p3=1
- set - command to set the port values
- p0...p3 - selectable ports, can be combined according to the needs
- duration - in [ms] defines the pin activation time (pulse LOW to HIGH and back)
- query starts with "?", more commands can be combined using "&". i.e. ...?p0=1&p3=1&p2=1&duration=1000
- sending values without 'duration' variable, set the port value to 1/0.

Command set - application

A basic python GUI application is provided, see basic_gui.py, to demostrate how to drive the RC car using the keyboard.

basic gui

By pressing the q,w,e,a,s,d keys the car will move like with the original remote control. If duration set from the trackbar, the key pressed will be reseted after a period of time. Letting the value on zero, allows the key repetitions. Note: q - left+forward, w - forward, e - right+forward, a-left, s-backward, d - right

The application provides a simple cmd_api function, that can be used to send commands from the python file. cmd_api("0001") - will set the ports p3=0, p2=0, p1=0, p0=1 cmd_api("xx01") - will set the ports p1=0, p0=1, while ignores p3, p2 settings

HW preparation

  • esp-01 module + programmer [1]
  • 1kOhm resitor for CH_PF pin to Vcc
  • 2x4 pin connector

ESP8266-01, source:[2]

Identify the button pins, see the picture below, and pins from ESP01 module above [2].

We will need to wire:

  • GND to the ground (- balck wire)
  • Vcc to the 3V (+ red wire)
  • IO1, IO2, TXD, RXD to the button pins
  • 1kOhm resistor, between esp Vcc and CH_PF pin Note: order of the GPIO pins does not matter, can be compensated from the SW.

Note: for more advanced RC controls, a set of relays or optocoupler can be added between the GPIOs and buttons. for This RC no galvanic separation was needed.

After the wiring is ready, the RC_car_controls_test.ino code can be uploaded to test all the connections for the buttons to work. If you are confident that all is working, edit the RC_car_wifi_control.ino project and put your local SSID for the WiFi and password.

Improvements
  1. An on/off button could be added to separate the esp8266-01 from the permanent supply when connected to the RC.
  2. Update the HW with the optocoupler variant for more generic use.
  3. Masking the set functions port parameters when processed in the SW.
  4. Send commands without the "duration" parameter to set permanently the GPIOs (on or off). In this way, the solution can be used for diverse IoT projects.

Resources

  1. Flash Program ESP-01 using USB Serial Adapter
  2. ESP-01 802.11 b/g/n Wi-Fi Module
  3. HTTP Request Methods
  4. send http requests as fast as possible in-python

/Enjoy.