5 Replies Latest reply on Jun 17, 2015 1:20 AM by cont_

    Intel Edison + mraa + Sparkfun GPIO Block + PIR + digital read() and isr not work


      Hi guys,


      I'm new in the forum and apologize in advance for my bad English.


      I've been trying for the last days to get digital read and interrupt working by using a PIR sensor and some others, but I always have the same problem.

      Here's my setup: I have an Edison with the Sparkfun Console Block and the GPIO Block, and I have to use Python, so I can use mraalib to program it.

      I want to use a PIR sensor (parallax PIR sensor 555-28027): when it detects motion a green LED lights up, otherwise it remains on the red.

      I connected  VDD and GND of the PIR, and output signal directly to pin GP13 of the Sparkfun GPIO block, that is mraa number 14.


      Here is my code. When I try to read the sensor's output, I just get the high value, never the low.

      Can someone help me and tell me where I'm wrong?


      # Import required Python libraries
      import mraa
      import time
      # Map GPIO block pins to MRAA pin numbers
      pin_GP13 = 14
      pin_GP15 = 48
      pin_GP14 = 36
      # Pin setup
      pir = mraa.Gpio(pin_GP13)
      greenLed = mraa.Gpio(pin_GP15)
      redLed = mraa.Gpio(pin_GP14)
      # Variables
      pirCalibrationPeriod = 45.0 # 45 sec
      # Function that toggle the led ON/OFF  
      LED_ON = 1
      LED_OFF = 0
      def Toggle(led, state):
      def main():  
          # Define pin direction
          print "\nPIR Module Test (CTRL+C to exit)\n"
          # Time to calibrate the sensor's output
          print "Waiting for PIR to settle: don't move anything in front of it ...\n"
          startCalibration = time.time()
          pirCalibrationTime = startCalibration + pirCalibrationPeriod
          # Wait for PIR calibration
          while (time.time() < pirCalibrationTime):
          print "Ready to work!"
          print "Move the hand in front of the sensor to detect motion.\n"
          # Turn redLed ON
          Toggle(redLed, LED_ON)
          triggers = 0
          while True:
              # Read and print PIR's state
              #print "IN =", pir1.read()     <-------------------------------- I ONLY READ 1 HERE! *********************
              pirState = 0
              pirState = pir.read()         <-------------------------------- I ONLY READ 1 HERE! *********************
              if (pirState == 1):
                  triggers = triggers + 1
                  print "PIR ALARM! Record number:", triggers, "- greenLed ON"
                  # Turn OFF the red led and turn ON the green one for a second
                  Toggle(redLed, LED_OFF)
                  Toggle(greenLed, LED_ON)
                  time.sleep(1.0)     # 1 sec delay
                  Toggle(greenLed, LED_OFF)
                  # Pause for 2 sec
                  Toggle(redLed, LED_ON)
                  print "No motion detected - redLed ON"
      if __name__ == "__main__":
          except KeyboardInterrupt:
              # Turn OFF leds
              Toggle(greenLed, LED_OFF)
              Toggle(redLed, LED_OFF)
              print "\n\nExit pir.py - Bye!\n"


      Again, if I try to use interupt to detect the low-high transition, nothing works. Here's the code, only the main function change.


      class State():
          state = 0
      pir_state = State()
      # ISR function of the PIR
      def Motion(args):
          print "Motion detected!"
          # Read the sensor output
          pir_state.state = pir.read()
          print "Sensor output value: " + str(pir_state.state)
          # Turn greenLed ON
          Toggle(greenLed, LED_ON)
      def main():   
          # Define pin direction
          pir1.edge(mraa.EDGE_RISING)     <--- IS IT NECESSARY? ******     
          # ISR for pir1
          pir.isr(mraa.EDGE_RISING, Motion, Motion)   <------------------ NOTHING WORKS HERE! *********************
          # Delay


      Thank you all in advance.