RaspberryPi pigame servo controll

I hooked up a servo onto my RaspberryPi 3, and i want to control it. I am currently using pygame library. It is installed and is a latest version. This is my code :

# Import libraries
import RPi.GPIO as GPIO
import time
import pygame
from pygame.locals import *

pygame.init()

# Set GPIO numbering mode
GPIO.setmode(GPIO.BOARD)
# Set pin 11 as an output, and define as servo1 as PWM pin
GPIO.setup(11,GPIO.OUT)
servo = GPIO.PWM(11,50) # pin 11 for servo1, pulse 50Hz
# Start PWM running, with value of 0 (pulse off)
servo.start(0)
angle = 90.0
servo.ChangeDutyCycle(2+(angle/18))
time.sleep(0.5)
servo.ChangeDutyCycle(0)
changed = False

while 1:
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_a:
                if angle > 10:
                    angle = angle - 5
                    changed = True
            elif event.key == pygame.K_d:
                if angle < 170:
                    angle = angle + 5
                    changed = True
            elif event.key == pygame.K_q:
                break
           
        if changed:
            servo.ChangeDutyCycle(2+(angle/18))
            time.sleep(0.5)
            servo.ChangeDutyCycle(0)
            time.sleep(1.5)
            changed = False

#Clean things up at the end
servoH.stop()
GPIO.cleanup()
pygame.quit()

But it does not detect an event. I keep hitting the keybord keys and the servo just stands still. I debugged it, and it detects no keybord/mouse events what so ever.

Please help.

Solution

Your code is ok, but it's not possible to receive window events (like key-presses) without a window.

Adding a window to your program makes it work OK.

Here's my test-code:

# Import libraries
#import RPi.GPIO as GPIO
import time
import pygame
from pygame.locals import *

SCREEN_WIDTH = 600
SCREEN_HEIGHT= 400

BLACK  = (   0,   0,   0 )
YELLOW = ( 255, 255,   0 )

pygame.init()
screen = pygame.display.set_mode( ( SCREEN_WIDTH, SCREEN_HEIGHT ) )

"""
# Set GPIO numbering mode
GPIO.setmode(GPIO.BOARD)
# Set pin 11 as an output, and define as servo1 as PWM pin
GPIO.setup(11,GPIO.OUT)
servo = GPIO.PWM(11,50) # pin 11 for servo1, pulse 50Hz
# Start PWM running, with value of 0 (pulse off)
servo.start(0)
servo.ChangeDutyCycle(2+(angle/18))
time.sleep(0.5)
servo.ChangeDutyCycle(0)
"""
angle = 90.0
changed = False
running = True

font = pygame.font.SysFont( None, 25 )
angle_label = font.render( "Angle: %4.2f" % ( angle ), True, YELLOW )


while running:
    for event in pygame.event.get():
    if event.type == pygame.QUIT:
        running = False
    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_a:
            if angle > 10:
                angle = angle - 5
                changed = True
        elif event.key == pygame.K_d:
            if angle < 170:
                angle = angle + 5
                changed = True
        elif event.key == pygame.K_q:
            break
       
    if changed:
        """
        servo.ChangeDutyCycle(2+(angle/18))
        time.sleep(0.5)
        servo.ChangeDutyCycle(0)
        time.sleep(1.5)
        """
        angle_label = font.render( "Angle: %4.2f" % ( angle ), True, YELLOW )
        changed = False

    # Update the display
    screen.fill( BLACK )
    screen.blit( angle_label, ( 50, 50 ) )
    pygame.display.update()

#Clean things up at the end
"""
servoH.stop()
GPIO.cleanup()
"""
pygame.quit()

Note that using time.sleep() is not ideal in PyGame code, because it blocks the event-loop. Your OS may consider your application to have locked-up, and prompt the user to terminate it. It would be better to use real-time timestamps to implement this delay manually - only sending updates to the servo when the time-window allows it.