97 lines
2.5 KiB
Python
Executable File
97 lines
2.5 KiB
Python
Executable File
#!/usr/bin/python
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# Python driver for SRF04 and SRO05 Ultrasonic sensors
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# Modified to use PINS not BCM : Dave Conway-Jones
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#import
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import RPi.GPIO as GPIO
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import time
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import sys
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import os, select
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# Turn off warnings if you run it a second time...
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GPIO.setwarnings(False)
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ECHO = 0
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TRIGGER = 0
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OLD = 0
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SLEEP = 0.5
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def Measure():
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start = 0
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GPIO.output(TRIGGER, True)
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time.sleep(0.00001)
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GPIO.output(TRIGGER, False)
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channel = GPIO.wait_for_edge(ECHO, GPIO.BOTH, timeout=200)
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if channel is None:
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print("Ultrasonic sensor timed out (pre-echo).")
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GPIO.remove_event_detect(ECHO)
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restart()
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# else:
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# print("Echo start detected")
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start = time.time()
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GPIO.wait_for_edge(ECHO, GPIO.BOTH, timeout=400)
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if channel is None:
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print("Ultrasonic sensor timed out (post-echo).")
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GPIO.remove_event_detect(ECHO)
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restart()
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# else:
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# print("Echo finish detected")
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stop = time.time()
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elapsed = stop-start
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distance = (elapsed * 34300)/2 # Using speed of sound at 20C (68F)
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return distance
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def restart():
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# print("Restarting...")
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GPIO.setmode(GPIO.BOARD) # Use GPIO BOARD numbers
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GPIO.setup(TRIGGER, GPIO.OUT) # Trigger
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GPIO.output(TRIGGER, False) # Set low
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GPIO.setup(ECHO, GPIO.OUT) # Echo
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GPIO.output(ECHO, False)
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time.sleep(0.1)
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GPIO.setup(ECHO,GPIO.IN)
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GPIO.add_event_detect(ECHO, GPIO.BOTH)
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time.sleep(2.0)
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# Main program loop
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if len(sys.argv) > 1:
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pins = sys.argv[1].lower().split(',')
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if len(pins) != 3:
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print "Bad parameters supplied"
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print pins
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sys.exit(0)
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TRIGGER = int(pins[0])
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ECHO = int(pins[1])
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SLEEP = float(pins[2])
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restart()
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# Flush stdin so we start clean
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while len(select.select([sys.stdin.fileno()], [], [], 0.0)[0])>0:
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os.read(sys.stdin.fileno(), 4096)
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while True:
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try:
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distance = int( Measure() + 0.5 )
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if distance != OLD and distance > 2 and distance < 400:
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print(distance)
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OLD = distance
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time.sleep(SLEEP)
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except Exception as e: # try to clean up on exit
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print(e) # Print error message on exception
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GPIO.remove_event_detect(ECHO)
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GPIO.cleanup(TRIGGER)
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GPIO.cleanup(ECHO)
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sys.exit(0)
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else:
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print "Bad params"
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print " sudo nrsrf.py trigger_pin,echo_pin,rate_in_seconds"
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sys.exit(0)
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