robotics with the Raspberry Pi

User Control for Remote Control Raspberry Pi Car





import RPi.GPIO as gpio
import sys
import time
####
import Tkinter as tk




def init():
    gpio.setmode(gpio.BOARD)
    gpio.setup(7, gpio.OUT)
    gpio.setup(11, gpio.OUT)
    gpio.setup(13, gpio.OUT)
    gpio.setup(15, gpio.OUT)
    #gpio.output(7, True)
    #gpio.output(11, True)

def forward(tf):
    #init()
    gpio.output(13, True)
    gpio.output(15, False)
    
    gpio.output(7, False)
    gpio.output(11, True)
    time.sleep(tf)
    gpio.cleanup()
    
def reverse(tf):
    #init()
    gpio.output(13, False)
    gpio.output(15, True)
    
    gpio.output(7, True)
    gpio.output(11, False)
    time.sleep(tf)
    gpio.cleanup()


def pivot_left(tf):
    #init()
    gpio.output(13, True)
    gpio.output(15, False)
    gpio.output(7, True)
    gpio.output(11, False)
    time.sleep(tf)
    gpio.cleanup()
    

def pivot_right(tf):
    #init()
    gpio.output(13, False)
    gpio.output(15, True)
    gpio.output(7, False)
    gpio.output(11, True)
    time.sleep(tf)
    gpio.cleanup()



def turn_left(tf):
    #init()
    gpio.output(7, True)
    gpio.output(11, True)
    gpio.output(13, True)
    gpio.output(15, False)
    time.sleep(tf)
    gpio.cleanup()


def turn_right(tf):
    #init()
    gpio.output(7, False)
    gpio.output(13, False)
    gpio.output(15, False)
    gpio.output(11, True)

    time.sleep(tf)
    gpio.cleanup()


def key_input(event):
    init()
    print 'Key:', event.char
    key_press = event.char
    sleep_time = 0.030

    if key_press.lower() == 'w':
        forward(sleep_time)
    elif key_press.lower() == 's':
        reverse(sleep_time)
    elif key_press.lower() == 'a':
        turn_left(sleep_time)
    elif key_press.lower() == 'd':
        turn_right(sleep_time)
    elif key_press.lower() =='q':
        pivot_left(sleep_time)
    elif key_press.lower() == 'e':
        pivot_right(sleep_time)
    
        


root = tk.Tk()
root.bind('<KeyPress>', key_input)
root.mainloop()

		

Alright, there is a bit more to this script. I will explain what is happening here, though you can also watch the video for a more in-depth explanation.

First, we needed some way to create a key-logger. The only way I know how is a non-headless way, which is okay, but not ideal. To do it, we're using event-handling built into Tkinter.

Note: import syntax for tkinter is different in Python 2 and Python 3. This is the Python 2 syntax here.

Our Tkinter application is just a simple window that records key presses. It's basically a key-logger.

Since our keylogger application is looping, we no longer need to call the init() function at the beginning of each of the functions.

Our major addition is the key_input() function, which is mainly our tkinter rules. The idea here is to print out what key is being pressed, after running an init(). Then, we define key_press as the key that is pressed.

Next, we have a sleep_time. I chose 0.030 because that allowed me to press and hold the keys for a while, release, and things would stop. Depending on a lot of small variables, your ideal time may vary. Try a few, and make sure you eliminate the lag.

Now we just define rules for each of the possible, acceptable, key-presses.

The next tutorial:






  • Robotics with the Raspberry Pi
  • Programming GPIO example
  • Running GPIO
  • Building Autonomous / RC car intro
  • Supplies needed
  • Motor Control
  • Connecting the four motors
  • Forward and Reverse
  • Turning
  • Pivoting
  • User Control
  • Remotely controlling the car
  • Adding a distance sensor (HC-SR04)
  • Programming with the distance sensor
  • Autopilot and/or auto-correct
  • Autonomous Beginnings
  • Testing Autonomous Code
  • Streaming video example one
  • Less latency streaming option