Raspberry Pi PIR motion sensor and camera script dies after loop

Question

I have a simple code for PIR sensor to detect a movement, which works as expected. Code:

from gpiozero import MotionSensor
import time

pir = MotionSensor(4)

while True:
        pir.wait_for_motion()
        print("You moved")
        pir.wait_for_no_motion()

Now when I want to use it with my camera, what happens is it works the first time, if a movement is presented it will take a picture and loops around, but after the second movement it crashes each time. Code:

from gpiozero import MotionSensor
from picamera import PiCamera
import time

pir = MotionSensor(4)

while True:
        pir.wait_for_motion()
        camera = PiCamera()
        camera.rotation = 180
        camera.start_preview(fullscreen=False, window = (50, 25, 640, 480))
        print("You moved")
        time.sleep(1)
        camera.capture('/home/pi/Desktop/image.jpg')
        #camera.stop_preview()
        pir.wait_for_no_motion()

And this is the dump of the error message:

pi@raspberrypi:~/Desktop $ python test.py 
You moved
mmal: mmal_vc_port_enable: failed to enable port vc.null_sink:in:0(OPQV): ENOSPC
mmal: mmal_port_enable: failed to enable connected port (vc.null_sink:in:0(OPQV))0x88c990 (ENOSPC)
mmal: mmal_connection_enable: output port couldn't be enabled
Traceback (most recent call last):
  File "test.py", line 10, in <module>
    camera = PiCamera()
  File "/usr/lib/python2.7/dist-packages/picamera/camera.py", line 433, in __init__
    self._init_preview()
  File "/usr/lib/python2.7/dist-packages/picamera/camera.py", line 513, in _init_preview
    self, self._camera.outputs[self.CAMERA_PREVIEW_PORT])
  File "/usr/lib/python2.7/dist-packages/picamera/renderers.py", line 558, in __init__
    self.renderer.inputs[0].connect(source).enable()
  File "/usr/lib/python2.7/dist-packages/picamera/mmalobj.py", line 2212, in enable
    prefix="Failed to enable connection")
  File "/usr/lib/python2.7/dist-packages/picamera/exc.py", line 184, in mmal_check
    raise PiCameraMMALError(status, prefix)
picamera.exc.PiCameraMMALError: Failed to enable connection: Out of resources

Answer 1

You should move the camera initialisation stuff outside the while loop.

from gpiozero import MotionSensor     
from picamera import PiCamera 
import time

pir = MotionSensor(4)
camera = PiCamera()
camera.rotation = 180
camera.start_preview(fullscreen=False, window = (50, 25, 640, 480))

while True:
    pir.wait_for_motion()
    print("You moved")
    time.sleep(1)
    camera.capture('/home/pi/Desktop/image.jpg')
    #camera.stop_preview() 
    pir.wait_for_no_motion()

That should solve your issue in my opinion.