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.. _py_keyboard_control:

3. Keyboard Control
================================


In this project, we will learn how to use the keyboard to remotely control the PiCar-X. 
You can control the PiCar-X to move forward, backward, left, and right.

**Run the Code**

.. raw:: html

    <run></run>

.. code-block::

    cd ~/picar-x/example
    sudo python3 3.keyboard_control.py

Press keys on keyboard to control PiCar-X! 

    * w: Forward 
    * a: Turn left 
    * s: Backward 
    * d: Turn right
    * i: Head up
    * k: Head down
    * j: Turn head left
    * l: Turn head right     
    * ctrl + c: Press twice to exit the program

**Code**

.. code-block:: python

    from picarx import Picarx
    from time import sleep
    import readchar

    manual = '''
    Press keys on keyboard to control PiCar-X!
        w: Forward
        a: Turn left
        s: Backward
        d: Turn right
        i: Head up
        k: Head down
        j: Turn head left
        l: Turn head right
        ctrl+c: Quit
    '''

    def show_info():
        print("\033[H\033[J",end='')  # clear terminal windows
        print(manual)


    if __name__ == "__main__":
        try:
            pan_angle = 0
            tilt_angle = 0
            px = Picarx()
            show_info()
            while True:
                key = readchar.readkey()
                key = key.lower()
                if key in('wsadikjl'): 
                    if 'w' == key:
                        px.set_dir_servo_angle(0)
                        px.forward(80)
                    elif 's' == key:
                        px.set_dir_servo_angle(0)
                        px.backward(80)
                    elif 'a' == key:
                        px.set_dir_servo_angle(-35)
                        px.forward(80)
                    elif 'd' == key:
                        px.set_dir_servo_angle(35)
                        px.forward(80)
                    elif 'i' == key:
                        tilt_angle+=5
                        if tilt_angle>35:
                            tilt_angle=35
                    elif 'k' == key:
                        tilt_angle-=5
                        if tilt_angle<-35:
                            tilt_angle=-35
                    elif 'l' == key:
                        pan_angle+=5
                        if pan_angle>35:
                            pan_angle=35
                    elif 'j' == key:
                        pan_angle-=5
                        if pan_angle<-35:
                            pan_angle=-35                 

                    px.set_cam_tilt_angle(tilt_angle)
                    px.set_cam_pan_angle(pan_angle)      
                    show_info()                     
                    sleep(0.5)
                    px.forward(0)
            
                elif key == readchar.key.CTRL_C:
                    print("\n Quit")
                    break

        finally:
            px.set_cam_tilt_angle(0)
            px.set_cam_pan_angle(0)  
            px.set_dir_servo_angle(0)  
            px.stop()
            sleep(.2)


**How it works?**

PiCar-X should take appropriate action based on the keyboard characters read. 
The ``lower()`` function converts upper case characters into lower case characters, 
so that the letter remains valid regardless of case.

.. code-block:: python

    while True:
        key = readchar.readkey()
        key = key.lower()
        if key in('wsadikjl'): 
            if 'w' == key:
                pass
            elif 's' == key:
                pass
            elif 'a' == key:
                pass
            elif 'd' == key:
                pass
            elif 'i' == key:
                pass
            elif 'k' == key:
                pass
            elif 'l' == key:
                pass
            elif 'j' == key:
                pass             
    
        elif key == readchar.key.CTRL_C:
            print("\n Quit")
            break