#!File: /usr/lib/cgi-bin/test_sensors.py
#!Version: 20mar2014
#!Discover and test any DS18B20 temperature sensors
#!Run from user space (/home/pi)
#!/usr/bin/env python
import os
import time
import glob
#-------------------------------------------------------------------------------------------------------
# global variables
speriod=(15*60)-1
#speriod=(5*60)-1
#-------------------------------------------------------------------------------------------------------
# get temperature
# returns None on error, or the temperature as a float
def get_temp(devicefile,devicenumber):
try:
fileobj = open(devicefile,'r')
lines = fileobj.readlines()
fileobj.close()
except:
return None
# get the status from the end of line 1
status = lines[0][-4:-1]
equals_pos = lines[1].find('t=')
if equals_pos != -1:
tempstr = lines[1][equals_pos+2:]
print "Read Sensor",
print devicenumber
print "Raw Data = ",
print tempstr,
tempvalue_c=float(tempstr)/1000.0
print tempvalue_c, "Degrees C"
tempvalue_f = tempvalue_c * 9.0 / 5.0 + 32.0
print tempvalue_f, "Degrees F"
tempvalue = round(tempvalue_f,1)
print tempvalue, "Rounded"
return tempvalue
else:
print "There was an error."
return None
#-------------------------------------------------------------------------------------------------------
# main function
# This is where the program starts
def main():
# enable kernel modules
os.system('sudo modprobe w1-gpio')
os.system('sudo modprobe w1-therm')
print "Looking for W1_Slave Temperature Sensor Devices..."
# search for a device file that starts with 28
devicelist = glob.glob('/sys/bus/w1/devices/28*')
print " "
devicecount = len(devicelist)
print "Number of W1_Slave Devices found:",
print devicecount
print " "
for deviceindex in xrange(0,devicecount):
print "Sensor " +str(deviceindex)+ " ID: " +devicelist[deviceindex]
print " "
if devicelist=='':
return None
# while True:
# get the temperatures from the device files
for deviceindex in xrange(0,devicecount):
w1devicefile = devicelist[deviceindex] +'/w1_slave'
temperature = get_temp(w1devicefile,deviceindex)
if temperature != None:
print "Sensor " +str(deviceindex) +" Temperature = " +str(temperature) +" F"
print " "
else:
# Sometimes reads fail on the first attempt
# so we need to retry
temperature = get_temp(w1devicefile[deviceindex],deviceindex)
if temperature != None:
print "Sensor " +str(deviceindex) +" Temperature = " +str(temperature) +" F"
print " "
else:
print "Error Reading Sensor " +str(deviceindex)
# time.sleep(speriod)
if __name__=="__main__":
main()
