device reports readiness to read but returned no data

[sepulworld]

Getting a lot of the following errors. Anyone else encountered this before?

read failed: device reports readiness to read but returned no data (device disconnected or multiple access on port?)

Perhaps because serial port is trying to be accessed by another process or should be disalbed at boot? I'm presently trying to integrate with BaleanOS for easier device deployments. Perhaps a config.txt boot setting could cause this?

[sepulworld]

The first pm_values = pms5003.read() works fine and gets data from device and pushes to luftdaten. It is any subsequent device reads that cause this error. Ill try reseting the connection before reads

[sepulworld]

Doesn't seem to help to add a preemtive reset. It appears there is a try/except loop I am gettings stuck inside of the pms5003.read() call.

Docker:

FROM balenalib/raspberry-pi-debian-python:3.7.3-stretch-build

WORKDIR /usr/src

RUN pip3 install numpy --user --no-binary :all:

RUN pip3 install enviroplus \
  requests \
  smbus

RUN install_packages python3-pil libatlas-base-dev python3-dev

RUN pip3 install spidev RPi.GPIO

WORKDIR /usr/src

COPY luftdaten.py luftdaten.py

CMD ["python3", "luftdaten.py"]

Slightly modifed luftdaten.py from example (ran into some issues with how Popen was being used, removed LCD outputs, not needed for use case).

#!/usr/bin/env python

import requests
import time
from bme280 import BME280
from pms5003 import PMS5003, ReadTimeoutError
from subprocess import PIPE, check_output, run

try:
    from smbus2 import SMBus
except ImportError:
    from smbus import SMBus

try:
    bus = SMBus(1)
except Exception as e:
    print(e)

# Create BME280 instance
try:
    bme280 = BME280(i2c_dev=bus)
except Exception as e:
    print(e)

# Create PMS5003 instance
try:
    pms5003 = PMS5003()
except Exception as e:
    print(e)

# Read values from BME280 and PMS5003 and return as dict
def read_values():
    values = {}
    cpu_temp = get_cpu_temperature()
    raw_temp = bme280.get_temperature()
    comp_temp = raw_temp - ((cpu_temp - raw_temp) / comp_factor)
    values["temperature"] = "{:.2f}".format(comp_temp)
    values["pressure"] = "{:.2f}".format(bme280.get_pressure() * 100)
    values["humidity"] = "{:.2f}".format(bme280.get_humidity())
    try:
        pm_values = pms5003.read()
        values["P2"] = str(pm_values.pm_ug_per_m3(2.5))
        values["P1"] = str(pm_values.pm_ug_per_m3(10))
    except ReadTimeoutError:
        pms5003.reset()
        pm_values = pms5003.read()
        values["P2"] = str(pm_values.pm_ug_per_m3(2.5))
        values["P1"] = str(pm_values.pm_ug_per_m3(10))
    return values

# Get CPU temperature to use for compensation
def get_cpu_temperature():
    process = run(['vcgencmd', 'measure_temp'], stdout=PIPE)
    output = process.stdout.decode('utf-8')
    return float(output.split('=')[1].split("'")[0])

# Get Raspberry Pi serial number to use as ID
def get_serial_number():
    with open('/proc/cpuinfo', 'r') as f:
        for line in f:
            if line[0:6] == 'Serial':
                return str(line.split(":")[1].strip())

# Check for Wi-Fi connection
def check_wifi():
    if check_output(['hostname', '-I']):
        return True
    else:
        return False

def send_to_luftdaten(values, id):
    pm_values = dict(i for i in values.items() if i[0].startswith("P"))
    temp_values = dict(i for i in values.items() if not i[0].startswith("P"))

    resp_1 = requests.post("https://api.luftdaten.info/v1/push-sensor-data/",
             json={
                 "software_version": "enviro-plus 0.0.1",
                 "sensordatavalues": [{"value_type": key, "value": val} for
                                      key, val in pm_values.items()]
             },
             headers={
                 "X-PIN":    "1",
                 "X-Sensor": id,
                 "Content-Type": "application/json",
                 "cache-control": "no-cache"
             }
    )

    resp_2 = requests.post("https://api.luftdaten.info/v1/push-sensor-data/",
             json={
                 "software_version": "enviro-plus 0.0.1",
                 "sensordatavalues": [{"value_type": key, "value": val} for
                                      key, val in temp_values.items()]
             },
             headers={
                 "X-PIN":    "11",
                 "X-Sensor": id,
                 "Content-Type": "application/json",
                 "cache-control": "no-cache"
             }
    )

    if resp_1.ok and resp_2.ok:
        return True
    else:
        return False

# Compensation factor for temperature
comp_factor = 1.2

# Raspberry Pi ID to send to Luftdaten
id = "raspi-" + get_serial_number()

# Main loop to read data and send to Luftdaten
while True:
    values = None
    try:
        values = read_values()
        print(values)
        resp = send_to_luftdaten(values, id)
        print("Response: {}\n".format("ok" if resp else "failed"))
        time.sleep(10)
    except Exception as e:
        print(e)

[sepulworld]

Ok, it was the serial device not being disabled properly.

root@1c75adf:~# mount -o remount,rw /
root@1c75adf:~# systemctl mask serial-getty@serial0.service
root@1c75adf:~# reboot

did the trick on the BalenaOS... just need to figure out how to add to device configs.