Initial checkin - program uses polling on gpio

graph.sh

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+#!/bin/sh
+rrdtool graph counter.gif \
+  -s 'now -20 hour' -e 'now' \
+  -X 0 -A \
+  DEF:counter=water.rrd:counter:LAST \
+  LINE2:counter#000000:"Zählerstand [m³]"
+display counter.gif&
+rrdtool graph consum.gif \
+  -s 'now -20 hour' -e 'now' \
+  DEF:consum=water.rrd:consum:AVERAGE \
+  CDEF:consumltr=consum,60000,* \
+  LINE2:consumltr#00FF00:"Verbrauch [l/min]" 
+display consum.gif&

setup.sh

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+gpio export 9 in

wairc.py

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+#!/usr/bin/python -u
+#
+# emeir.py
+# 
+# Program to read the electrical meter using a reflective light sensor
+# This is the data recording part running on a Raspberry Pi.
+# It retrieves data from the Arduino over USB serial and stores
+# counter and consumption values into a round robin database.
+
+# Copyright 2015 Martin Kompf
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import serial
+import time
+import sys
+import os
+import re
+import argparse
+import rrdtool
+
+# GPIO value files (wiringPi)
+gpin = '/sys/class/gpio/gpio9/value'
+
+# counter unit: 1 revolution = x m^3
+trigger_step = 0.001
+
+# Path to RRD with counter values
+count_rrd = "%s/water.rrd" % (os.path.dirname(os.path.abspath(__file__)))
+
+
+# Create the Round Robin Database
+def create_rrd():
+  print 'Creating RRD: ' + count_rrd
+  # Create RRD to store counter and consumption:
+  # Counter is GAUGE (m^3)
+  # Consumption is ABSOLUTE (m^3/s)
+  # 1 value per minute for 3 days
+  # 1 value per day for 30 days
+  # 1 value per week for 10 years
+  # Consolidation LAST for counter
+  # Consolidation AVERAGE for consumption
+  try:
+    rrdtool.create(count_rrd, 
+      '--no-overwrite',
+      '--step', '60',
+      'DS:counter:GAUGE:86400:0:1000000',
+      'DS:consum:ABSOLUTE:86400:0:1000000',
+      'RRA:LAST:0.5:1:4320',
+      'RRA:AVERAGE:0.5:1:4320',
+      'RRA:LAST:0.5:1440:30',
+      'RRA:AVERAGE:0.5:1440:30',
+      'RRA:LAST:0.5:10080:520',
+      'RRA:AVERAGE:0.5:10080:520')
+  except Exception as e:
+    print 'Error ' + str(e)
+
+# Get the last counter value from the rrd database
+def last_rrd_count():
+  val = 0.0
+  handle = os.popen("rrdtool lastupdate " + count_rrd)
+  for line in handle:
+    m = re.match(r"^[0-9]*: ([0-9.]*) [0-9.]*", line)
+    if m:
+      val = float(m.group(1))
+      break
+  handle.close()
+  return val
+
+# Main
+def main():
+  # Check command args
+  parser = argparse.ArgumentParser(description='Program to read the water meter using a reflective light sensor.')
+  parser.add_argument('-c', '--create', action='store_true', default=False, help='Create rrd database if necessary')
+  args = parser.parse_args()
+
+  if args.create:
+    create_rrd()
+
+  trigger_state = 0
+  counter = last_rrd_count()
+  print "restoring counter to %f" % counter
+
+  while(1==1):
+    # read gpio input value file
+    f = open(gpin, 'r')
+    line = f.read().strip()
+    f.close()
+
+    old_state = trigger_state
+    if line == '1':
+      trigger_state = 1
+    elif line == '0':
+      trigger_state = 0
+    if old_state == 1 and trigger_state == 0:
+      # trigger active -> update count rrd
+      counter += trigger_step
+      update = "N:%.3f:%.3f" % (counter, trigger_step)
+      #print update
+      rrdtool.update(count_rrd, update)
+    time.sleep(0.1)
+
+
+if __name__ == '__main__':
+  main()