I am not a brilliant coder, but someone had been asking for an example
of how to load 1-wire data into a database. So I am including this diddy
which does it in python. I am using Peter's fine owpython interface and
owserver. owserver is great for this, since it allows me to have owfs
around at the same time for other work. This code is the first stage of
the heating and cooling system for my house, really a controls lab that
my family happens to be inflicted with. (They have only grumbled
slightly when a bug stops all the cooling in the summer.)
I won't include the schema, as it is much more complex that this part
shows. I use Postgres as my dbms and love that as well. I hate python
less than other languages and Linux less than windows.
enjoy,
jerry
#! /usr/bin/python
# a script to pull a list of sensors from the db, read them from
# the one wire bus and store results into the db. New readings are
# archived and median values are stored into a current readings
# table. The table keeps a reading for each 15 minute interval over
# the last 4 hours.
#
# Things to fix:
# should use the scheduler to get consistent read intervals
# need to get constants via db queries
#
# you are welcome to use this at your own risk
# jerry scharf
import psycopg
import ow
import time
activepaths = []
sensors = {}
lastread = {}
priorread = {}
lastmread = {}
priormread = {}
median = {}
sleep_interval = 30
epoch_seconds = 450
median_hold_hours = 4
ow.init('127.0.0.1:2840')
ow.error_level(ow.error_level.fatal)
ow.error_print(ow.error_print.stderr)
conn = psycopg.connect("dbname='hcontrol' user='hcontroller'")
cur = conn.cursor()
while (1):
# print time.asctime()
read_count = 0
# start the simultaneaous temperature conversion on all 1-wire sensors
ow._put('/simultaneous/temperature','1')
# get the list of sensors to read
SQL = """SELECT id,ow_id FROM ow_sensors WHERE active = 1"""
cur.execute(SQL)
rows = cur.fetchall()
#loop through the rows doing reads and stores
for row in rows:
update = 0
owpath = '/%s' % row[1]
sensorid = int(row[0])
# create a sensor instance if it doesn't exist
if (not sensors.has_key(owpath)):
sensors[owpath] = ow.Sensor(owpath)
# print "new sensor object for %s" % owpath
# read the sensor and store it
try:
dummy = sensors[owpath].temperature
except ow.exUnknownSensor:
# print 'unknown sensor for %s' % owpath
continue
temp = float(dummy)
SQL = """INSERT INTO ow_sensor_readings (ow_sensor_id,value)
VALUES (%d, %f)""" % (sensorid,temp)
if (temp == 85):
# print 'reading was 85'
continue
read_count +=1
if (not lastread.has_key(owpath)):
lastread[owpath] = temp
priorread[owpath] = temp
lastmread[owpath] = temp
priormread[owpath] = temp
update = 1
elif (temp != 85 and temp != lastread[owpath] and temp !=
priorread[owpath]):
update = 1
if (update == 1):
cur.execute(SQL)
# compute the median of the last three readings
slist = list((temp,lastmread[owpath],priormread[owpath]))
slist.sort
median[owpath] = slist[1]
# compute the epoch and see if there is an existing epoch median
epoch = int(time.time()/epoch_seconds)
SQL = """SELECT id FROM sensor_medians WHERE epoch = %d AND
ow_sensor_id = %d""" % (epoch,sensorid)
cur.execute(SQL)
data = cur.fetchone()
if (data):
SQL = """UPDATE sensor_medians SET read_at = now() WHERE id
= %d""" % data[0]
cur.execute(SQL)
SQL = """UPDATE sensor_medians SET value = %s WHERE id =
%d""" % (median[owpath],data[0])
else:
SQL = """INSERT INTO sensor_medians
(ow_sensor_id,epoch,value,read_at) VALUES (%d,%d,%f,now())""" %
(sensorid, epoch, median[owpath])
cur.execute(SQL)
# bump the readings for the next time through
priormread[owpath] = lastmread[owpath]
lastmread[owpath] = temp
# save the new data for this sensor to the database
conn.commit()
# clean up old entries from the medians table
SQL = """DELETE FROM sensor_medians WHERE read_at < (now() -
interval'%d hour')""" % median_hold_hours
cur.execute(SQL)
conn.commit()
print 'sensors read = %d' % read_count
time.sleep(sleep_interval)
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