parsing script for rtl_433 analyze mode for acurite 5n1 vn1tx weather station

parse_rtl_433_acurite5n1.py

#!/usr/bin/python

""" parse rtl_433 output for acurite 5n1 sensor """

# http://www.acurite.com/acurite-5-in-1-sensor

import re
import fileinput

samples = """
[04] {66} c6 84 38 80 65 00 4f 94 00 : 11000110 10000100 00111000 10000000 01100101 00000000 01001111 10010100 00000000 
[09] {66} d6 88 71 00 ca 00 4f 9c 00 : 11010110 10001000 01110001 00000000 11001010 00000000 01001111 10011100 00000000 
[14] {65} e6 88 71 00 ca 00 9f 48 00 : 11100110 10001000 01110001 00000000 11001010 00000000 10011111 01001000 00000000 
[04] {65} c6 88 78 00 c9 28 33 ea 00 : 11000110 10001000 01111000 00000000 11001001 00101000 00110011 11101010 00000000 
[09] {65} d6 88 78 00 c9 28 33 fa 00 : 11010110 10001000 01111000 00000000 11001001 00101000 00110011 11111010 00000000 
[14] {65} e6 88 78 00 c9 28 33 0a 00 : 11100110 10001000 01111000 00000000 11001001 00101000 00110011 00001010 00000000 
[09] {66} d6 88 78 00 69 28 b1 0c 80 : 11010110 10001000 01111000 00000000 01101001 00101000 10110001 00001100 10000000 
[14] {65} e6 88 78 00 69 28 b2 29 00 : 11100110 10001000 01111000 00000000 01101001 00101000 10110010 00101001 00000000 
[04] {65} c6 88 71 00 3a 00 9f 98 00 : 11000110 10001000 01110001 00000000 00111010 00000000 10011111 10011000 00000000 
[09] {65} d6 88 71 00 3a 00 9f a8 00 : 11010110 10001000 01110001 00000000 00111010 00000000 10011111 10101000 00000000 
[14] {65} e6 88 71 00 3a 00 9f b8 00 : 11100110 10001000 01110001 00000000 00111010 00000000 10011111 10111000 00000000 
"""

# TODOs
# dedup/verify triple lines?
# verify parity bits on data bytes
# parse id and channel bits for info?

WIND_DIRECTIONS_CARDINAL = [
    "NNW",
    "NW",
    "WNW",
    "W",
    "WSW",
    "SW",
    "SSW",
    "S",
    "SSE",
    "SE",
    "ESE",
    "E",
    "ENE",
    "NE",
    "NNE",
    "N"  ]
    

def checksum(bytes):
    """ verify checksum """
    # sum of first seven bytes modulo 256 should equal eighth byte
    total = 0
    checksum = bytes[7]
    
    for i in range(7):
        total += bytes[i]
    
    if total % 256 == checksum:
        return True
    else:
        return False

def getTemp(bytes):
    # range: -40 to 158 F
    highbits = ( bytes[4] & 0x0F ) << 7
    lowbits = bytes[5] & 0x7F
    rawtemp = highbits | lowbits
    temp = (rawtemp - 400) / 10.0
    return temp

def getWindSpeed(bytes):
    # range: 0 to 159 kph
    highbits = ( bytes[3] & 0x1F ) << 3
    lowbits = ( bytes[4] & 0x70 ) >> 4
    speed = highbits | lowbits
    return speed

def getWindDirection(bytes):
    # range: 16 compass points, ccw from (NNW) to 15 (N)
    direction = bytes[4] & 0x0F
    return WIND_DIRECTIONS_CARDINAL[direction]

def getHumidity(bytes):
    # range: 1% to 99% RH
    humidity = bytes[6] & 0x7F
    return humidity

def getRainfall(bytes):
    # rolling? counter increments 0.01 in
    # 0 to 99.99 in range
    raincounter = bytes[6] & 0x7F
    return raincounter

for line in fileinput.input(bufsize=1):
    match = re.search('\[\d+\] {6\d} ([^:]+)', line)
    if match:
        bytestring = match.group(1).split()    #  payload
        bytes = [ int(b, 16) for b in bytestring ]
        if checksum(bytes):
            if bytes[2] & 0x0F == 1:
                # wind speed, wind direction, rainfall
                print "wind speed, kph:", getWindSpeed(bytes)
                print "wind direction:", getWindDirection(bytes)
                print "rain counter (0.01 in incr):", getRainfall(bytes)
            elif bytes[2] & 0x0F == 8:
                # wind speed, temp, rh
                print "wind speed, kph:", getWindSpeed(bytes)
                print "temp, F:", getTemp(bytes)
                print "humidity, %:", getHumidity(bytes)
            print "----"