bminer · May 21, 2018 15:25 · Mirankumer · Sep 14, 2021 · bminer · Sep 15, 2021
diff --git a/range_sensor.py b/range_sensor.py
 #!/usr/bin/python

 # Measure distance to water level in sump pit using
 # HC-SR04 ultrasonic ranging module
 # Sensor info:
 #	2cm - 4m. range with ~3mm. accuracy, 15 degree measuring angle
 #	5VDC, 15mA working current
 # Suggestion in spec to connect ground before 5VDC line when hot plugging
 # Measure surface area no less than 0.5 m^2 (really?)

 # range_sensor.py
 # Prints the current date/time and measurement in cm. as CSV
 # Calls another process if reading falls below threshold

 import RPi.GPIO as GPIO
 import time
 import datetime
 import os
 import subprocess

 # Minimum distance to water level (cm) / threshold
 MIN_DISTANCE = 24.5

 # Calculate median of a list
 def median(lst):
 	lst = sorted(lst)
 	if len(lst) < 1:
 		return None
 	if len(lst) %2 == 1:
 		return lst[((len(lst)+1)/2)-1]
 	else:
 		return float(sum(lst[(len(lst)/2)-1:(len(lst)/2)+1]))/2.0

 # Sensor Pinout
 TRIG = 23
 ECHO = 24

 # Set mode and data direction
 GPIO.setmode(GPIO.BCM)
 GPIO.setup(TRIG, GPIO.OUT)
 GPIO.setup(ECHO, GPIO.IN)

 # Speed of sound constant
 # 343 m / sec. is rougly the speed of sound in dry air at 20C
 # The speed decreases with temperature and increases a bit with more humidity
 # This is a cool, damp basement, so we'll assume 341 m / sec. (15C / 59F with 60%RH)
 # Sensor measures round-trip time, so we divide by 2 to get half of that distance
 SPEED = 17050

 distances = []
 sampleCount = 0
 while sampleCount < 30:
 	# Distance Measurement In Progress

 	# Limit sample rate to every 10ms (even though spec recommends 60ms)
 	time.sleep(0.01)

 	# Send 10uS pulse
 	GPIO.output(TRIG, True)
 	time.sleep(0.00001)
 	GPIO.output(TRIG, False)

 	# Waiting for ECHO to go high...
 	# Max. wait 1 second using pulse_end as temp variable
 	pulse_start = time.time()
 	pulse_end = time.time()
 	while GPIO.input(ECHO)==0 and pulse_start - pulse_end < 1:
 		pulse_start = time.time()

 	# Waiting for ECHO to go low... (max. wait 1 second)
 	pulse_end = time.time()
 	while GPIO.input(ECHO)==1 and pulse_end - pulse_start < 1:
 		pulse_end = time.time()

 	# Append distance measurement to samples array
 	distances.append((pulse_end - pulse_start) * SPEED)
 	sampleCount = sampleCount + 1

 # Cleanup (set GPIOs to input, etc.)
 GPIO.cleanup()
 # Print date/time and median measurment in cm.
 median = round(median(distances), 1)
 print datetime.datetime.now().strftime("%Y-%m-%d %H:%M") + "," + str(median)
 # Notify of problem if water level is high
 if median < MIN_DISTANCE:
 	subprocess.call(["node", os.path.dirname(os.path.realpath(__file__)) + "/email_warning.js", str(median)])
	#!/usr/bin/python

	# Measure distance to water level in sump pit using
	# HC-SR04 ultrasonic ranging module
	# Sensor info:
	# 2cm - 4m. range with ~3mm. accuracy, 15 degree measuring angle
	# 5VDC, 15mA working current
	# Suggestion in spec to connect ground before 5VDC line when hot plugging
	# Measure surface area no less than 0.5 m^2 (really?)

	# range_sensor.py
	# Prints the current date/time and measurement in cm. as CSV
	# Calls another process if reading falls below threshold

	import RPi.GPIO as GPIO
	import time
	import datetime
	import os
	import subprocess

	# Minimum distance to water level (cm) / threshold
	MIN_DISTANCE = 24.5

	# Calculate median of a list
	def median(lst):
	lst = sorted(lst)
	if len(lst) < 1:
	return None
	if len(lst) %2 == 1:
	return lst[((len(lst)+1)/2)-1]
	else:
	return float(sum(lst[(len(lst)/2)-1:(len(lst)/2)+1]))/2.0

	# Sensor Pinout
	TRIG = 23
	ECHO = 24

	# Set mode and data direction
	GPIO.setmode(GPIO.BCM)
	GPIO.setup(TRIG, GPIO.OUT)
	GPIO.setup(ECHO, GPIO.IN)

	# Speed of sound constant
	# 343 m / sec. is rougly the speed of sound in dry air at 20C
	# The speed decreases with temperature and increases a bit with more humidity
	# This is a cool, damp basement, so we'll assume 341 m / sec. (15C / 59F with 60%RH)
	# Sensor measures round-trip time, so we divide by 2 to get half of that distance
	SPEED = 17050

	distances = []
	sampleCount = 0
	while sampleCount < 30:
	# Distance Measurement In Progress

	# Limit sample rate to every 10ms (even though spec recommends 60ms)
	time.sleep(0.01)

	# Send 10uS pulse
	GPIO.output(TRIG, True)
	time.sleep(0.00001)
	GPIO.output(TRIG, False)

	# Waiting for ECHO to go high...
	# Max. wait 1 second using pulse_end as temp variable
	pulse_start = time.time()
	pulse_end = time.time()
	while GPIO.input(ECHO)==0 and pulse_start - pulse_end < 1:
	pulse_start = time.time()

	# Waiting for ECHO to go low... (max. wait 1 second)
	pulse_end = time.time()
	while GPIO.input(ECHO)==1 and pulse_end - pulse_start < 1:
	pulse_end = time.time()

	# Append distance measurement to samples array
	distances.append((pulse_end - pulse_start) * SPEED)
	sampleCount = sampleCount + 1

	# Cleanup (set GPIOs to input, etc.)
	GPIO.cleanup()
	# Print date/time and median measurment in cm.
	median = round(median(distances), 1)
	print datetime.datetime.now().strftime("%Y-%m-%d %H:%M") + "," + str(median)
	# Notify of problem if water level is high
	if median < MIN_DISTANCE:
	subprocess.call(["node", os.path.dirname(os.path.realpath(__file__)) + "/email_warning.js", str(median)])
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