#!/usr/bin/python

# Python code to read values from Smart Meter via SML (smart message language) 
# created: Alexander Kabza, Mar 1, 2016
# last mod: Alexander Kabza, 2017-10-25
# For documentation and further information see http://www.kabza.de/MyHome/SmartMeter.html

import sys
import serial
import time

def writexml(t, W, P):
    file = open('/var/www/html/SmartMeter.xml', 'w')
    file.write('<MyHomePower><SmartMeter><data name=\"timestamp\" value=\"' + t + '\"  valueunit=\"YYYY-MM-DD hh:mm:ss\" /><data name=\"energy\" value=\"' + str(W) + '\" valueunit=\"Wh\" /><data name=\"power\" value=\"' + str(P) + '\" valueunit=\"W\" /></SmartMeter></MyHomePower>') 
    file.close()

port = serial.Serial(
    port='/dev/ttyAMA0',
    baudrate=9600,
    parity=serial.PARITY_NONE,
    stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS
)

#port.open();

start = '1b1b1b1b01010101'
end = '1b1b1b1b1a'

data = ''

while True:
    char = port.read()
    data = data + char.encode('HEX')
    pos = data.find(start)
    if (pos <> -1):
        data = data[pos:len(data)]
    pos = data.find(end)
    if (pos <> -1):
#        print data + '\n'
        timestamp = (time.strftime("%Y-%m-%d ") + time.strftime("%H:%M:%S"))
        result = timestamp
        
#        search = '070100000000ff'
#        pos = data.find(search)
#        if (pos <> -1):
#            pos = pos + len(search) + 10
#            value = data[pos:pos + 18]
#            print 'ID: ' + search + ' = ' + value + ' = ' + value.decode('HEX')

        search = '070100010800ff'
        pos = data.find(search)
        if (pos <> -1):
            pos = pos + len(search) + 14
            value = data[pos:pos + 16]
            energy = int(value, 16) / 1e4
#            print 'kWh: ' + search + ' = ' + value + ' = ' + str(energy) + ' kWh'
            result = result + ';' +  str(energy)

        search = '070100010700ff'
        pos = data.find(search)
        if (pos <> -1):
            pos = pos + len(search) + 14
            value = data[pos:pos + 8]
            power = int(value, 16) / 1e2
#            print 'W: ' + search + ' = ' + value + ' = ' + str(power) + ' W'
            result = result + ';' +  str(power)

        writexml(timestamp, energy, power) 
        
        file = open('/home/pi/output.csv', 'a')
        file.write (result + '\n')
        file.close()

#        file = open('message.dat', 'w')
#        file.write (data)
#        file.close()
        
        data = ''