In the meantime I found a solution.
For anybody who is interested. I added a writing method using websockets...
Here is the entire script:
#!/usr/bin/python -u
# coding=utf-8
# "DATASHEET": http://cl.ly/ekot
# https://gist.github.com/kadamski/92653913a53baf9dd1a8
from __future__ import print_function
import serial, struct, sys, time, json, subprocess
####### ADDED
import paho.mqtt.publish as publish
import psutil
import string
# The ThingSpeak Channel ID.
# Replace <YOUR-CHANNEL-ID> with your channel ID.
channelID = "1061352"
# The write API key for the channel.
# Replace <YOUR-CHANNEL-WRITEAPIKEY> with your write API key.
writeAPIKey = "RJASGFLWRVM5JKHM"
# The hostname of the ThingSpeak MQTT broker.
mqttHost = "mqtt.thingspeak.com"
# You can use any username.
mqttUsername = "Roger NotKnoMuch"
# Your MQTT API key from Account > My Profile.
mqttAPIKey = "GIE04M6OE1XPQWX0"
# Define websocket on Port 80
tTransport = "websockets"
tPort = 80
# Create the topic string.
topic = "channels/" + channelID + "/publish/" + writeAPIKey
######## ADDED END
DEBUG = 0
CMD_MODE = 2
CMD_QUERY_DATA = 4
CMD_DEVICE_ID = 5
CMD_SLEEP = 6
CMD_FIRMWARE = 7
CMD_WORKING_PERIOD = 8
MODE_ACTIVE = 0
MODE_QUERY = 1
PERIOD_CONTINUOUS = 0
JSON_FILE = '/var/www/html/aqi.json'
MQTT_HOST = ''
MQTT_TOPIC = '/weather/particulatematter'
ser = serial.Serial()
ser.port = "/dev/ttyUSB0"
ser.baudrate = 9600
ser.open()
ser.flushInput()
byte, data = 0, ""
def dump(d, prefix=''):
print(prefix + ' '.join(x.encode('hex') for x in d))
def construct_command(cmd, data=[]):
assert len(data) <= 12
data += [0,]*(12-len(data))
checksum = (sum(data)+cmd-2)%256
ret = "\xaa\xb4" + chr(cmd)
ret += ''.join(chr(x) for x in data)
ret += "\xff\xff" + chr(checksum) + "\xab"
if DEBUG:
dump(ret, '> ')
return ret
def process_data(d):
r = struct.unpack('<HHxxBB', d[2:])
pm25 = r[0]/10.0
pm10 = r[1]/10.0
checksum = sum(ord(v) for v in d[2:8])%256
return [pm25, pm10]
#print("PM 2.5: {} μg/m^3 PM 10: {} μg/m^3 CRC={}".format(pm25, pm10, "OK" if (checksum==r[2] and r[3]==0xab) else "NOK"))
def process_version(d):
r = struct.unpack('<BBBHBB', d[3:])
checksum = sum(ord(v) for v in d[2:8])%256
print("Y: {}, M: {}, D: {}, ID: {}, CRC={}".format(r[0], r[1], r[2], hex(r[3]), "OK" if (checksum==r[4] and r[5]==0xab) else "NOK"))
def read_response():
byte = 0
while byte != "\xaa":
byte = ser.read(size=1)
d = ser.read(size=9)
if DEBUG:
dump(d, '< ')
return byte + d
def cmd_set_mode(mode=MODE_QUERY):
ser.write(construct_command(CMD_MODE, [0x1, mode]))
read_response()
def cmd_query_data():
ser.write(construct_command(CMD_QUERY_DATA))
d = read_response()
values = []
if d[1] == "\xc0":
values = process_data(d)
return values
def cmd_set_sleep(sleep):
mode = 0 if sleep else 1
ser.write(construct_command(CMD_SLEEP, [0x1, mode]))
read_response()
def cmd_set_working_period(period):
ser.write(construct_command(CMD_WORKING_PERIOD, [0x1, period]))
read_response()
def cmd_firmware_ver():
ser.write(construct_command(CMD_FIRMWARE))
d = read_response()
process_version(d)
def cmd_set_id(id):
id_h = (id>>8) % 256
id_l = id % 256
ser.write(construct_command(CMD_DEVICE_ID, [0]*10+[id_l, id_h]))
read_response()
def pub_mqtt(jsonrow):
cmd = ['mosquitto_pub', '-h', MQTT_HOST, '-t', MQTT_TOPIC, '-s']
print('Publishing using:', cmd)
with subprocess.Popen(cmd, shell=False, bufsize=0, stdin=subprocess.PIPE).stdin as f:
json.dump(jsonrow, f)
if __name__ == "__main__":
cmd_set_sleep(0)
cmd_firmware_ver()
cmd_set_working_period(PERIOD_CONTINUOUS)
cmd_set_mode(MODE_QUERY);
while True:
cmd_set_sleep(0)
for t in range(15):
values = cmd_query_data();
if values is not None and len(values) == 2:
print("PM2.5: ", values[0], ", PM10: ", values[1])
time.sleep(2)
# open stored data
try:
with open(JSON_FILE) as json_data:
data = json.load(json_data)
except IOError as e:
data = []
# check if length is more than 100 and delete first element
if len(data) > 100:
data.pop(0)
# append new values
jsonrow = {'pm25': values[0], 'pm10': values[1], 'time': time.strftime("%d.%m.%Y %H:%M:%S")}
data.append(jsonrow)
# save it
with open(JSON_FILE, 'w') as outfile:
json.dump(data, outfile)
if MQTT_HOST != '':
pub_mqtt(jsonrow)
###### ADDED
# get the system performance data over 20 seconds.
pm25 = values[0]
pm10 = values[1]
# build the payload string.
payload = "field1=" + str(pm25) + "&field2=" + str(pm10)
# attempt to publish this data to the topic.
try:
publish.single(topic, payload, hostname=mqttHost, transport=tTransport, port=tPort,auth={'username':mqttUsername,'password':mqttAPIKey})
print (" Published Data = ",pm25," and ", pm10," to host: " , mqttHost , " clientID= " , clientID)
except (KeyboardInterrupt):
break
except:
print ("There was an error while publishing the data.")
###### ADDED END
print("Going to sleep for 1 min...")
# Alter time.sleep = 1200
cmd_set_sleep(1)
time.sleep(1200)
