The following code (and the output from it) is to summarize my initial
findings using Marcus Priesch's pyowfs library. It may help someone who
wants to quickly evaluate this library and avoid some of the pitfalls I
fell into. The most significant for me was how to locate a sensor based
on the sensor's UUID without having to iterate and parse. [I intend to
have multiple sensors of the same type in my application. Each one
measures a different temperature and to access these different
temperatures unambiguously I need to locate the specific sensor by
UUID]. Thanks again Marcus for helping me sort this out.
Joe P.
-------- Code Start ----------
#! /usr/bin/env python
"""
Sample code to illustrate basic read operations using the pyowfs library
"""
from pyowfs import Connection
# Stage 1 - Connect to OWSERVER
root = Connection ("localhost:4304")
# Stage 2 - Access the 1-wire information
print "List of all devices present"
for s in root.find () : print s # This lists all the devices available
on the bus.
print "This also is a listing of all devices present"
for i in root.iter_sensors () :
print i
print "List of devices of type DS18B20 (a temperature sensor)"
s = root.find (type = "DS18B20")
print s
print 'Assigning DS18B20 Sensors ...'
s0 = root.find (type = "DS18B20")[0]
s1 = root.find (type = "DS18B20")[1]
print "Sensor 0:"
print s0
print "Temperature from Sensor 0:"
print s0.get("temperature")
print "Sensor 1:"
print s1
print "Temperature from Sensor 1:"
print s1.get("temperature")
print "Selecting a sensor by ID (F758DC020000)"
"""
NOTE
The ID of a sensor does not include the characters before the
decimal point
(28 in this case) and the decimal point itself.
"""
s = root.find (id="F758DC020000") [0]
temp = s.get ("temperature")
print "Printing Temp from F758DC020000..."
print temp
print 'List One-wire filesystem content under the root node ...'
for e in root.iter_entries () : print e
print 'List One-wire filesystem content under the bus.0 directory ...'
for f in root.get ("bus.0").iter_entries () : print f
print 'List One-wire filesystem content under the bus.0\interface
directory ...'
for g in root.get ("bus.0").get("interface").iter_entries () : print g
" ... etc. ..."
print "End of Program"
----------- End of Code -----------
-------- Output Start --------
pi@raspberrypi ~/MyFiles/OWFS/code $ ./temperature_pyowfs_3.py
List of all devices present
<Sensor /28.450EDC020000/ - DS18B20>
<Sensor /28.F758DC020000/ - DS18B20>
<Sensor /81.A7D12F000000/ - DS1420>
This also is a listing of all devices present
<Sensor /28.450EDC020000/ - DS18B20>
<Sensor /28.F758DC020000/ - DS18B20>
<Sensor /81.A7D12F000000/ - DS1420>
List of devices of type DS18B20 (a temperature sensor)
[<Sensor /28.450EDC020000/ - DS18B20>, <Sensor /28.F758DC020000/ - DS18B20>]
Assigning DS18B20 Sensors ...
Sensor 0:
<Sensor /28.450EDC020000/ - DS18B20>
Temperature from Sensor 0:
21.8125
Sensor 1:
<Sensor /28.F758DC020000/ - DS18B20>
Temperature from Sensor 1:
21.6875
Selecting a sensor by ID (F758DC020000)
Printing Temp from F758DC020000...
21.6875
List One-wire filesystem content under the root node ...
<Dir '/bus.0/'>
<Dir '/uncached/'>
<Dir '/settings/'>
<Dir '/system/'>
<Dir '/statistics/'>
<Dir '/structure/'>
<Dir '/simultaneous/'>
<Dir '/alarm/'>
List One-wire filesystem content under the bus.0 directory ...
<Dir '/bus.0/interface/'>
<Dir '/bus.0/bus.0/'>
<Dir '/bus.0/uncached/'>
<Dir '/bus.0/settings/'>
<Dir '/bus.0/system/'>
<Dir '/bus.0/statistics/'>
<Dir '/bus.0/structure/'>
<Dir '/bus.0/simultaneous/'>
<Dir '/bus.0/alarm/'>
List One-wire filesystem content under the bus.0\interface directory ...
<Dir '/bus.0/interface/settings/'>
<Dir '/bus.0/interface/statistics/'>
End of Program
-------- Output End --------
--
Regards
Joe P.
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