keyboard_control.py

# Autor:	Ingmar Stapel
# Date:		20141229
# Version:	1.0
# Homepage:	www.raspberry-pi-car.com

import sys, tty, termios, os
import L298NHBridge as HBridge
import wirus

speedleft = 0
speedright = 0

# Instructions for when the user has an interface
print("w/s: direction")
print("a/d: steering")
print("e: autonomous mode")
print("q: stops the motors")
print("p: print motor speed (L/R)")
print("x: exit")

# The catch method can determine which key has been pressed
# by the user on the keyboard.
def getch():
    fd = sys.stdin.fileno()
    old_settings = termios.tcgetattr(fd)
    try:
        tty.setraw(sys.stdin.fileno())
        ch = sys.stdin.read(1)
    finally:
        termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
    return ch

# Infinite loop
# The loop will not end until the user presses the
# exit key 'X' or the program crashes...

def printscreen():
    # Print the motor speed just for interest
    os.system('clear')
    print("w/s: direction")
    print("a/d: steering")
    print("q: stops the motors")
    print("x: exit")
    print("========== Speed Control ==========")
    print "left motor:  ", speedleft
    print "right motor: ", speedright

while True:
    # Keyboard character retrieval method. This method will save
    # the pressed key into the variable char
    char = getch()

    # The car will drive forward when the "w" key is pressed
    if(char == "w"):

        # synchronize after a turning the motor speed

        # if speedleft > speedright:
        # speedleft = speedright

        # if speedright > speedleft:
        # speedright = speedleft

        # accelerate the RaPi car
        speedleft = speedleft + 0.1
        speedright = speedright + 0.1

        if speedleft > 1:
            speedleft = 1
        if speedright > 1:
            speedright = 1

        HBridge.setMotorLeft(speedleft)
        HBridge.setMotorRight(speedright)
        printscreen()

        # The car will reverse when the "s" key is pressed
    if(char == "s"):

        # synchronize after a turning the motor speed

        # if speedleft > speedright:
        # speedleft = speedright

        # if speedright > speedleft:
        # speedright = speedleft

        # slow down the RaPi car
        speedleft = speedleft - 0.1
        speedright = speedright - 0.1

        if speedleft < -1:
            speedleft = -1
        if speedright < -1:
            speedright = -1

        HBridge.setMotorLeft(speedleft)
        HBridge.setMotorRight(speedright)
        printscreen()

        # Stop the motors
    if(char == "q"):
        speedleft = 0
        speedright = 0
        HBridge.setMotorLeft(speedleft)
        HBridge.setMotorRight(speedright)
        printscreen()

        # The "d" key will toggle the steering right
    if(char == "d"):
        #if speedright > speedleft:
        speedright = speedright - 0.1
        speedleft = speedleft + 0.1

        if speedright < -1:
            speedright = -1

        if speedleft > 1:
            speedleft = 1

        HBridge.setMotorLeft(speedleft)
        HBridge.setMotorRight(speedright)
        printscreen()

        # The "a" key will toggle the steering left
    if(char == "a"):
        #if speedleft > speedright:
        speedleft = speedleft - 0.1
        speedright = speedright + 0.1

        if speedleft < -1:
            speedleft = -1

        if speedright > 1:
            speedright = 1

        HBridge.setMotorLeft(speedleft)
        HBridge.setMotorRight(speedright)
        printscreen()

    # The "x" key will break the loop and exit the program
    if(char == "x"):
        HBridge.setMotorLeft(0)
        HBridge.setMotorRight(0)
        HBridge.exit()
        print("Program Ended")
        break

    if (char == "e"):
        HBridge.exit()
        wirus.Wirus()

        # The keyboard character variable char has to be set blank. We need
    # to set it blank to save the next key pressed by the user
    char = ""
# End