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node-red-nodes/hardware/PiSrf/nrsrf.py

92 lines
2.4 KiB
Python
Executable File

#!/usr/bin/python
#
# Copyright 2015 IBM Corp.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Python driver for SRF04 and SRO05 Ultrasonic sensors
# Modified to use PINS not BCM : Dave Conway-Jones
#import
import RPi.GPIO as GPIO
import time
import sys
import os, select
# Turn off warnings if you run it a second time...
GPIO.setwarnings(False)
ECHO = 0
TRIGGER = 0
OLD = 0
def Measure():
start = 0
realstart = 0
realstart = time.time()
GPIO.output(TRIGGER, True)
time.sleep(0.00001)
GPIO.output(TRIGGER, False)
start = time.time()
while GPIO.input(ECHO)==0:
start = time.time()
Dif = time.time() - realstart
if Dif > 0.2:
print("Ultrasonic Sensor Timed out, Restarting.")
time.sleep(0.4)
Main()
while GPIO.input(ECHO)==1:
stop = time.time()
elapsed = stop-start
distance = (elapsed * 36000)/2
return distance
# Main program loop
if len(sys.argv) > 1:
pins = sys.argv[1].lower().split(',')
if len(pins) != 2:
print "Bad number of pins supplied"
print pins
sys.exit(0)
TRIGGER = int(pins[0])
ECHO = int(pins[1])
GPIO.setmode(GPIO.BOARD) # Use GPIO BOARD numbers
GPIO.setup(TRIGGER, GPIO.OUT) # Trigger
GPIO.setup(ECHO, GPIO.OUT) # Echo
GPIO.output(ECHO, False)
GPIO.setup(ECHO,GPIO.IN)
# Flush stdin so we start clean
while len(select.select([sys.stdin.fileno()], [], [], 0.0)[0])>0:
os.read(sys.stdin.fileno(), 4096)
while True:
try:
distance = int( Measure() + 0.5 )
if distance != OLD:
print(distance)
OLD = distance
time.sleep(0.5)
except: # try to clean up on exit
print("0.0");
GPIO.cleanup(TRIGGER)
GPIO.cleanup(ECHO)
sys.exit(0)
else:
print "Bad params"
print " sudo nrsrf.py trigger_pin,echo_pin"
sys.exit(0)