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distance-lcd.py
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distance-lcd.py
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#!/usr/bin/python
#+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
#|R|a|s|p|b|e|r|r|y|P|i|-|S|p|y|.|c|o|.|u|k|
#+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
#
# ultrasonic_1.py
# Measure distance using an ultrasonic module
#
# Ultrasonic related posts:
# http://www.raspberrypi-spy.co.uk/tag/ultrasonic/
#
# Author : Matt Hawkins
# Date : 16/10/2016
# -----------------------
# Import required Python libraries
from __future__ import print_function
import time
import RPi.GPIO as GPIO
import Adafruit_CharLCD as LCD
# Raspberry Pi pin configuration:
lcd_rs = 27 # Note this might need to be changed to 21 for older revision Pi's.
lcd_en = 22
lcd_d4 = 25
lcd_d5 = 24
lcd_d6 = 23
lcd_d7 = 18
lcd_backlight = 4
# Define LCD column and row size for 16x2 LCD.
lcd_columns = 16
lcd_rows = 2
# Initialize the LCD using the pins above.
lcd = LCD.Adafruit_CharLCD(lcd_rs, lcd_en, lcd_d4, lcd_d5, lcd_d6, lcd_d7,
lcd_columns, lcd_rows, lcd_backlight)
msg = "Distance:\n %5.1f"
# Use BCM GPIO references
# instead of physical pin numbers
GPIO.setmode(GPIO.BCM)
# Define GPIO to use on Pi
#GPIO_TRIGGER = 23
GPIO_TRIGGER = 16
#GPIO_ECHO = 24
GPIO_ECHO = 19
# Speed of sound in cm/s at temperature
#temperature = 20
temperature = 25
speedSound = 33100 + (0.6*temperature)
print("Ultrasonic Measurement")
print("Speed of sound is",speedSound/100,"m/s at ",temperature,"deg")
# Set pins as output and input
GPIO.setup(GPIO_TRIGGER,GPIO.OUT) # Trigger
GPIO.setup(GPIO_ECHO,GPIO.IN) # Echo
while 1:
# Set trigger to False (Low)
GPIO.output(GPIO_TRIGGER, False)
# Allow module to settle
time.sleep(0.5)
# Send 10us pulse to trigger
GPIO.output(GPIO_TRIGGER, True)
# Wait 10us
time.sleep(0.00001)
GPIO.output(GPIO_TRIGGER, False)
start = time.time()
while GPIO.input(GPIO_ECHO)==0:
start = time.time()
while GPIO.input(GPIO_ECHO)==1:
stop = time.time()
# Calculate pulse length
elapsed = stop-start
# Distance pulse travelled in that time is time
# multiplied by the speed of sound (cm/s)
distance = elapsed * speedSound
# That was the distance there and back so halve the value
distance = distance / 2
lcd.clear()
msg_formatted = msg % (distance)
print(msg_formatted)
lcd.message(msg_formatted)
time.sleep(1)
# Reset GPIO settings
GPIO.cleanup()