Print Data from a Sensor raspberry pi3

Print Data from a Sensor

To demonstrate how to print data from a sensor, here’s a program that displays the temperature from a DS18B20 Digital Temperature Sensor. There is some set up to do before you can get this to work on the Raspberry Pi, so check out our tutorial on the DS18B20 to see how.

In general, you take the input variable from your sensor and convert it to an integer to perform any calculations. Then convert the result to a string, and output the string to the display using lcd.write_string(sensor_data()):

import os

import glob

import time

from RPLCD import CharLCD

lcd = CharLCD(cols=16, rows=2, pin_rs=37, pin_e=35, pins_data=[33, 31, 29, 23])

os.system('modprobe w1-gpio')

os.system('modprobe w1-therm')

base_dir = '/sys/bus/w1/devices/'

device_folder = glob.glob(base_dir + '28*')[0]

device_file = device_folder + '/w1_slave'

def read_temp_raw():

    f = open(device_file, 'r')

    lines = f.readlines()

    f.close()

    return lines

#CELSIUS CALCULATION

def read_temp_c():

    lines = read_temp_raw()

    while lines[0].strip()[-3:] != 'YES':

        time.sleep(0.2)

        lines = read_temp_raw()

    equals_pos = lines[1].find('t=')

    if equals_pos != -1:

        temp_string = lines[1][equals_pos+2:]

        temp_c = int(temp_string) / 1000.0 # TEMP_STRING IS THE SENSOR OUTPUT, MAKE SURE IT'S AN INTEGER TO DO THE MATH

        temp_c = str(round(temp_c, 1)) # ROUND THE RESULT TO 1 PLACE AFTER THE DECIMAL, THEN CONVERT IT TO A STRING

        return temp_c

#FAHRENHEIT CALCULATION

def read_temp_f():

    lines = read_temp_raw()

    while lines[0].strip()[-3:] != 'YES':

        time.sleep(0.2)

        lines = read_temp_raw()

    equals_pos = lines[1].find('t=')

    if equals_pos != -1:

        temp_string = lines[1][equals_pos+2:]

        temp_f = (int(temp_string) / 1000.0) * 9.0 / 5.0 + 32.0 # TEMP_STRING IS THE SENSOR OUTPUT, MAKE SURE IT'S AN INTEGER TO DO THE MATH

        temp_f = str(round(temp_f, 1)) # ROUND THE RESULT TO 1 PLACE AFTER THE DECIMAL, THEN CONVERT IT TO A STRING

        return temp_f

while True:

    lcd.cursor_pos = (0, 0)

    lcd.write_string("Temp: " + read_temp_c() + unichr(223) + "C")

    lcd.cursor_pos = (1, 0)

    lcd.write_string("Temp: " + read_temp_f() + unichr(223) + "F")

Well, that about covers most of what you’ll need to get started programming your LCD with Python. Try combining the programs to get some interesting effects. You can display data from multiple sensors by printing and clearing the screen or positioning the text. You can also make fun animations by scrolling custom characters. If you have any problems or questions about setting up an LCD or programming it, just leave a comment below. If you want to get an email notification when we publish new articles, enter your email in the subscribe box at the top of this post. Talk to you next time!