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Raspberry Pi Zero Temperature Data Logger Multiple DS18B20 sensors to Thingspeak

Former Member

I was using a project by Mike Davis (A Raspberry Pi Data Logger for about $25 (Temperature Probe and ThingSpeak).. All is working fine for one sensor but I have 3 and am unable to figure out a loop to get it to upload all three. I can see all three sensors in the /devices/ directory. Any help would be appreciated.

 

Here is code from Mike I'm using:

import os

 

import glob

 

import time

 

import sys

 

import datetime

 

import urllib2

 

 

 

baseURL = "https://api.thingspeak.com/update?api_key=YOURAPIKEY"

 

 

 

#initiate the temperature sensor

 

os.system('modprobe w1-gpio')

 

os.system('modprobe w1-therm')

 

 

 

#set up the location of the sensor in the system

 

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

 

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

 

device_file = device_folder + '/w1_slave'

 

 

 

def read_temp_raw(): #a function that grabs the raw temperature data from the sensor

 

     f = open(device_file, 'r')

 

     lines = f.readlines()

 

     f.close()

 

     return lines

 

 

 

def read_temp(): #a function that checks that the connection was good and strips out the temperature

 

     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 = float(temp_string)/1000.0

 

         temp_f = temp_c * 9.0/5.0 + 32.0

 

         return temp_c

 

 

 

while True: #infinite loop

 

     tempin = read_temp() #get the temp

 

     values = [datetime.datetime.now(), tempin]

 

     g = urllib2.urlopen(baseURL + "&field1=%s" % (tempin))

 

     time.sleep(60)

 

  • in reply to Former Member

    Dale,

     

    A little late in the day, but hopefully will help somebody else.

     

    I wanted to measure 3 temperatures: Fridge, Beer and Outside Air Temp (OAT).  My ThingSpeak channel: 115595

     

    I re-used the same code as you, but changed the variables in each section so that I had 3 unique sets:

    OAT

    Fridge

    Beer.

     

    To send to ThingSpeak,  I separated temperature variables by commas and assigned the variables to fields

     

    values = [datetime.datetime.now(), fridge_tempin, oat_tempin, beer_tempin]

     

    j = urllib2.urlopen(baseURL + "&field1=%s" % (fridge_tempin) + "&field2=%s" % (oat_tempin) + "&field3=%s" % (beer_tempin))

     

    Code:

    import os

    import glob

    import time

    import sys

    import datetime

    import urllib2

     

    baseURL = "https://api.thingspeak.com/update?api_key=EnterYourAPIKeyHere"

     

    os.system('modprobe w1-gpio')

     

    os.system('modprobe w1-therm')

     

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

     

    #beer temperature device location

    beer_file = '/sys/bus/w1/devices/28-011562a640ff/w1_slave'

     

    #fridge temperature Device Location

    fridge_file = '/sys/bus/w1/devices/28-011562be55ff/w1_slave'

     

    #OAT temperature device location

    oat_file = '/sys/bus/w1/devices/28-021562c6c9ff/w1_slave'

     

    #Determine beer temperature

    def read_rawtemp_beer():

         f = open(beer_file,'r')

         lines = f.readlines()

         f.close

         return lines

     

    def read_temp_beer():

         lines = read_rawtemp_beer()

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

              time.sleep(0.2)

              lines = read_rawtemp_beer()

         equals_pos = lines[1].find('t=')

         if equals_pos !=-1:

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

              temp_beer = float(temp_string)/1000.0

              return temp_beer

     

    #Determine Fridge Temperature

    def read_rawtemp_fridge():

         y = open(fridge_file,'r')

         lines = y.readlines()

         y.close

         return lines

     

    def read_temp_fridge():

         lines = read_rawtemp_fridge()

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

              time.sleep(0.2)

              lines = read_rawtemp_fridge()

         equals_pos = lines[1].find('t=')

         if equals_pos !=-1:

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

              temp_fridge = float(temp_string)/1000.0

              return temp_fridge

    #Determine OAT Temperature

    def read_rawtemp_oat():

         x = open(oat_file,'r')

         lines = x.readlines()

         x.close

         return lines

     

    def read_temp_oat():

         lines = read_rawtemp_oat()

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

              time.sleep(0.2)

              lines = read_rawtemp_oat()

         equals_pos = lines[1].find('t=')

              if equals_pos !=-1:

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

              temp_oat = float(temp_string)/1000.0

              return temp_oat

     

    while True: #Loop

     

    #Send Fridge Temperature to Thingspeak

         fridge_tempin = read_temp_fridge()

     

    #Send Beer Temperature to Thingspeak

         beer_tempin = read_temp_beer()

     

    #Send OAT temperature to Thingspeak

         oat_tempin = read_temp_oat()

     

    #Pull results together

         values = [datetime.datetime.now(), fridge_tempin, oat_tempin, beer_tempin]

     

    #Open Thingspeak channel and assign fields to temperatures

         j = urllib2.urlopen(baseURL + "&field1=%s" % (fridge_tempin) + "&field2=%s" % (oat_tempin) + "&field3=%s" % (beer_tempin))

     

    #Time to next loop

    time.sleep(600)

  • Ok, I know this wasn't the cleanest but all I could figure out for now. Hope it helps someone.

     

    I removed:

     

    while true: line

    time.sleep line

     

    changed the field to match which field i was uploading to and save three versions of the script. I then just call each script from a cron job running every 10 minutes.

     

    whatever I know it sucks there is a much better way but I played with the script until I gave up and did it the cheap way. It's working now just sucks to have to do it that way.

     

    Dale