Bit-River
commented
6 years ago I have tried this component with the Nova SDS011 and the same issue occurs.
As a test / work-around I made a small api in python. This code only recreated the error if automatically restarted at reboot time, when I delayed the start-up of the api by 30 seconds the issue stopped.
I recommend a delay be introduced before this component is loaded, and this may alleviate the issue. In the interim, the api below both work well and can be used in HA with a simple rest sensor.
Api code used for SDS021 testing:
#!/usr/bin/python
# Forked from: https://github.com/MatejKovacic/SDS011-SDS018-and-SDS021-dust-sensors-reader
# Credits: Matjaz Rihtar, Matej Kovacic
from flask import Flask, jsonify
import serial, struct, time
# Set default USB port
USBPORT = "/dev/ttyUSB0"
class SDS021Reader:
def __init__(self, inport):
self.serial = serial.Serial(port=inport, baudrate=9600)
def readValue( self ):
step = 0
while True:
while self.serial.inWaiting() != 0:
v = ord(self.serial.read())
if step == 0:
if v == 170:
step = 1
elif step == 1:
if v == 192:
values = [0,0,0,0,0,0,0]
step = 2
else:
step = 0
elif step > 8:
step = 0
# Compute PM2.5 and PM10 values
pm25 = (values[1]*256 + values[0])/10.0
pm10 = (values[3]*256 + values[2])/10.0
return [pm25,pm10]
elif step >= 2:
values[step - 2] = v
step = step + 1
app = Flask(__name__)
reader = SDS021Reader(USBPORT)
@app.route('/api/airquality', methods=['GET'])
def get_air_quality():
pm_25_value , pm_10_value = reader.readValue()
return jsonify({'PM25': str(pm_25_value), 'PM10': str(pm_10_value)})
if __name__ == '__main__':
app.run(host='0.0.0.0', debug=False)And for the SDS011:
#!/usr/bin/python
# coding=utf-8
# "DATASHEET": http://cl.ly/ekot
# https://gist.github.com/kadamski/92653913a53baf9dd1a8
from flask import Flask, jsonify
import serial, struct, time
CMD_MODE = 2
CMD_QUERY_DATA = 4
CMD_SLEEP = 6
MODE_ACTIVE = 0
MODE_QUERY = 1
ser = serial.Serial()
ser.port = "/dev/ttyUSB0"
ser.baudrate = 9600
ser.open()
ser.flushInput()
byte, data = 0, ""
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"
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]
def read_response():
byte = 0
while byte != "\xaa":
byte = ser.read(size=1)
d = ser.read(size=9)
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=1):
mode = 0 if sleep else 1
ser.write(construct_command(CMD_SLEEP, [0x1, mode]))
read_response()
app = Flask(__name__)
@app.route('/api/airquality', methods=['GET'])
def get_air_quality():
cmd_set_sleep(0)
cmd_set_mode(1);
quick_average_pm_two_five=[]
quick_average_pm_ten=[]
for t in range(5):
values = cmd_query_data();
if values is not None:
quick_average_pm_two_five.append(values[0])
quick_average_pm_ten.append(values[1])
time.sleep(1)
pm_25_value=(sum(quick_average_pm_two_five) / float(len(quick_average_pm_two_five)))
pm_10_value=(sum(quick_average_pm_ten) / float(len(quick_average_pm_ten)))
cmd_set_mode(0);
cmd_set_sleep()
quick_average_pm_two_five=[]
quick_average_pm_ten=[]
return jsonify({'PM25': str(pm_25_value), 'PM10': str(pm_10_value)})
if __name__ == '__main__':
app.run(host='0.0.0.0', debug=False)
sherazlodhi
balloobbot
calculin2001
jfedor2
Home Assistant release with the issue: 0.68, noticed since 0.66 when sensor first connected
Last working Home Assistant release (if known): Not known.
Operating environment (Hass.io/Docker/Windows/etc.): Hass.io, and Hassbian
Component/platform: Particulate Matter Sensor - https://www.home-assistant.io/components/sensor.serial_pm/
Description of problem:
Values from this sensor jump into a different range after a restart, and also after a reboot. Two+ restarts are then required to bring the sensor back into expected ranges.
Effect of issue can be seen in the graph below when Home Assistant is restarted at 13:10, 14:15, and again 14:55 when the values eventually return to the range the sensor reports usually. The air is of good quality where the sensor is placed, the context is the Irish countryside.
Ridiculous values have been recorded (smog city levels), and a reboot has fixed them:
Device, and configuration entry as below. Not tested with another device at this time.
Additional information:
I've mentioned this in the forum:
https://community.home-assistant.io/t/particulate-matter-sensor-nova-sds021-wildly-varying-values-anyone-else/49958