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PyCom LoPy or WiPy BME280/BME680 SDS011/PMS7003/SPS30 GPS MySense sensor kit

Status: rc1 2019/02/25

Copyright: 2019, Teus Hagen To enable further developments is is common in the Open Source world to support a public domain project financially or otherwise. Certainly if your product is based on this type of public domain licensed software.

Licensing: Open Source Initiative https://opensource.org/licenses/RPL-1.5 Unless explicitly acquired and licensed from Licensor under another license, the contents of this file are subject to the Reciprocal Public License ("RPL") Version 1.5, or subsequent versions as allowed by the RPL, and You may not copy or use this file in either source code or executable form, except in compliance with the terms and conditions of the RPL.

All software distributed under the RPL is provided strictly on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, AND LICENSOR HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT, OR NON-INFRINGEMENT. See the RPL for specific language governing rights and limitations under the RPL.

Goal: professional DIY durable simple low cost (ca €120) air quality sensor kits.

description

Overview of wiring and modules using a PCB board with Grove connectors to avoid soldiering and ease sensor replacements and extensions. Included are the 3D print files for the housing/case as well PCB board electronic design as well PCB board manufacturing instructions.

Comment: here we used the indoor dust sensor Plantower PMS7003. Use for outdoor the PMSx003 dust sensor. Other dust sensors as from Nova and Sensirion are supported.

Shopping list (ca € 100-150):

  • PyCom LoPy-4 controller PYCLOPY4 (Tinytronics € 35.-)
  • optional LoPy Expansie board 2.0 PYCEXPBOARD3.1 (Tinytronics € 19.-) (development board)
  • alternative is a DIY PCB connector board with 6 Grove connectors (3 TTL and 3 I2C) ca € 10 (incl the components (mosfet, resisters, pins). PCB board has optional components to be able to use solar panel power. See schema, PCB manufacturing mall, and battery guard schema and mall pwrsafe11. Our PCB has been made by Fontys Venlo GreenTechLab and updated by Land van Cuijk initiative.
  • LoPy-Sigfox antenne kit 868 Mhz PYCLOSIAN868KIT (Tinytronics € 10.50)
  • optional SSD1306 I2C Yellow/Blue 128X64 oled display (AliExpress € 2.23, Tinytronics € 9.50) E.g. Oled display
  • Sensirion SPS30 indoor laser PM sensor (Antratek: € 45.95, Ali Express € 25,90) Advised because the unit displays raw PM counts values and can be used outdoor. Plantower has a new PMSx003 (black) which has cleaning support and tube inlet (€ 80). E.g. PMSx003 dust sensor
  • Alternative is Nova SDS011 (bigger, less PM types, but has air inlet tube connection) E.g. SDS011 Nova dust sensor
  • optional GY-NE06MV2 NEO-6M GPS module TTL connection (AliExpress € 3.15) E.g. NEO6MV2 GPS module
  • optional Sensirion SHT31 (AliExpress € 2), BME280 (AliExpress € 3), E.g. Sensirion SHT31 meteo sensor
  • or better BME680 I2C (has interesting gas sensor, AliExpress € 10.50) meteo sensor (do not use I2C/TTL BME680, I2C bus errors) E.g. BME680 meteo sensor
  • wiring: per module 4 wires: female/male for 4 modules: Grove to female jumper 4 wire conversion cable 5 per pack Seed Studio € 5.00.

Remark: better to create a UART/I2C connector shield with Grove sockets and connectors. See the picture. Board design with Grove sockets is available. See the SVG file (and the picture) of the alternative PCB LoPy expansion board designed by Fontys Venlo GreenTechLab as example. * assortiment thrink tubes (2.5 mm and bigger) (€ 3.45 Ben's Electronics) * V220 outdoor cablebox 10X12.5 cm, larger is better eg OBO T100 or T160. (electroshop.nl € 5.39) Or use PVC pipes and roof air outlet exhaust. Advised is to paint it white and use double pipes for heat isolation. A double PVC pipe will lower the LoRa signal strength a bit. Make sure no wires are near the antenna.

Energy V230 supply (ca € 4):

  • long USB adapter cable 2-3 meter (Action € 1.50)
  • USB V220 AC - 5V dc adapter 1A (Action € 2.10)

or use solarpower if no V230 is available (ca € 100):

  • 12V to 5V step down (ca € 1): e.g. 5V USB
  • solar power regulator (ca € 10) e.g. Solar PR
  • battery guard to switch kit off if battery level is too low (DIY € 3). See pwrsafe1 schema. Make sure to apply a diode over the power connectors and capacitor as a wild change in solar power or on/off connection may destroy your controller. WARNING: without a capacitor (eg 100 uF 16V) the accu/solar combination or loose contact may blow away your controller. Make sure to use a good regulator. We measured a peak of 11.4 V on the 5V stepdown regulator in such cases.
  • or battery load (ca € 10) e.g. Solar power regulator
  • battery pack (ca € 60) e.g. battery 12V (needs 12V->5V).
  • solar panel (ca 16) e.g. Solar Panel
  • housing/case for the power

ToDo:

  • software to use WiFi/MQTT for internet access connectivity if LoRa is not available
  • Over The Air (OTA) update via the PyCom OTA method. Currenty one can use WiFi AP access and Atom. If the WiFi AP is powered off by configuration the LoRa command 'W' will enable WiFi AP of the node again for one hour.
  • Solar power regulator with watch dog for battery level. Currently the PCB in use has battery level support and will force deepsleeps untill battery level is high enough to be operational.

Some fixing materials:

  • 2 component glue
  • some fixing tool to stabalize the antenna. Or place the antenna inside the housing.
  • 4 cm tube for air inlet of PM module (SDS011 or PMSx003)
  • piece of wood to be able to attach the outdoor cable box on a wall.
  • some material to fixate the components and allow airflow in the box
  • or see 3-D print masks for double sided PVC housing contruction.

One may need to extend those dust sensors without an inlet tube and inlet as well as ouytet on same side with some air separation guidence in order to avoid to measure only the dust circulating within the housing.

LoPy kit casing

A simple housing case is made with a piece of plexiglas 61 X 230 mm (see for the dril mask for 3 mm dril the SVG file in the images directory). This plexiglas can be fixated within an PVC roof air outlet (length 300 mm diameter 80 mm) and some mosquito bait with PVC ring (socket). One may locate the LoRa antenna in the pipe or on the outside attached to the PVC ring. Make sure to paint the housing white and avoid direct sun on the kit.

Another housing can be made with a V230 outdoor connector box e.g. OBO T100 box.

A better housing can be made from PVC roof air outlet manufactured eg from BT Nyloplast Nld (€ 7.50). The components are mounted on a so called mother board from 3 mm plastic. To avoid solar heat use an internal PVC rain pipe. The motherboard can be fit in a 3D printer made socket. The oled display is fixed on the housing with a 3D printed container. The GPS antenna is glued inside the PVC pipe on a small table (3D print) and must point upwards. The LoRa antenna is fixated inside the PVC pipe as well.

images/Motherboard-3DprintComponentsLanternHousing.png All 3D printed components and mother board are found in the images folder ( 3D .stl en dcx (FreeCAD) files):

TTN gateway

DIY or buy one.

You may be unlucky and do not have a TTN infrastructure in the neighbourhood. However it is easy to build one your self with Pi controller, an IC880-SPI or RAK831 concentrator, pigtail and antenna in some casing, ca € 2000-230, Ideetron.nl or AliExpress) or buy one (ca € 350 (TTN gateway via Ideetron.nl) or higher € 450-1.200). See for how-to instructions:

For MySense we changed the /opt/ttn-gateway/bin/start.sh, added WiFi access point for WEBMIN (use INSTALL.sh WEBMIN and Raspberry Pi OS configuration (see INSTALL.sh help), and to log concentraor log messages to the oled display via the filter GatewayLogDisplay.py. The scripts can be found in the map LoRa. See the map LoRa (or Google to The Things Network) for more details and functionality add-on's to build a DIY TTN gateway.

The TTN ZH Pi based shopping list (we bought a ready to go gateway Pi2 based from IMST and changed the software to TTN for € 250):

  • Pi Zero or 3, poweradapter, minimal 4GB SDcard € 42 Tinytronics.nl
  • iC880A-SPI concentrator board (IMST websop CH) € 120 (ideetron.nl).
  • 868 MHz anternna and pigtail € 10
  • 7 Dupont wires (female/female) € 1
  • enclosure e.g. OBO T160 V220 cable box € 10
  • optional outdoor antenna with fuse(!) € 75 (ideetron.nl)

or:

  • RAK831 in case via AliExpress, which has GPS antenna and a too small LoRa antenna: € 178. The alluminium case does not allow WiFi signal of the on board chip to reach outside of the case. For WiFi you may need a USB WiFi dongle. If so make sure the dongle is able to be used as WiFi access point as well as WiFi client.
  • 6 dB glasfiber antenna via AliExpress: € 29 For Europe make sure you have a 868MHz version (use with AliExpress the color option).

For both types of boards install the ttn-gateway software from apt install git; git clone https://github.com/ttn-zh/ic880a.git/ ~/ic880a-gateway. Make always sure antenna is placed before you start to use the gateway! A start without the antenna connected will distroy the concentrator board. Configuration hint for software: make sure the right reset pin number of GPIO Pi is used (see start.sh shell command file, and do not use initialy the remote concentrator configuration. The concentrator board needs always to be reset before starting up the forwarding software.

DESCRIPTION

The sensor kits are build with PyCom (loPy-4 and WiPy-3) ESP controllers and PyCom expansion board. The controller has on board WiFi, BlueTooth and for LoPy LoRa. Use an external LoRa Wan 868/915 LoRa antenna on the LoPy. The PyCom controller can be programmed via embedded micropython. To access the board use the Atom with the Pymakr plugin. Atom is interfacing either via WiFi (192.168.4.1) or serial (USB) connection to the controller.

The goal is to use the PyCom ESP as controller for MySense sensor satallite kits. Measuring dust, rel. humidity and GPS to forward this to Mosquitto database (WiFi) or LoRa data concentrator. From which the MySense configured as proxy can pick up sensor data to the MySense databases.

Datacommunication is done via WiFi (Mosquitto), or LoRa (TTN MQTT data concentrator) and MySense Raspberry Pi in server mode. One may send data via MySense Pi server to RIVM in the Netherlands as well Luftdata in Germany.

measurement data

The MySense kit will collect measurements from dust (Nova SDS011, Plantower PMSn003 serie and Sensirion SPS30) sensors and meteo (BME280 or BME680 with air quality support) sensors and send this data either via wifi or LoRaWan (TTN) Mosquitto (MQTT) dataconcentrator, e.g. TTN-datacollector.py with different output backends. Dust measurements will be collected over a sample time (default 1 minute) and send to the data concentrator at interval (default 5 minutes) periods of time. Fan and laser of the dust sensors will be powered off in the idle periods of time. To ease the calibration of dust sensor one is advised to use sensors which beside the mass values also show the PM count values.

The MySense server will collect this information from the MQTT servers and formward these measurements and meta data to e.g. a MySQL database, spreadsheet or another data stream service.

One may need to clean the fan, or even lenses, e.g. on the event on high unexpected values. See how to teardown the Sensirion SPS30.

remote management

The LoRa MySense part is supporting remote control via TTN. The following remote commands are supported yet:

  • '?': send version, configuration and location details to TTN MQTT server
  • 'O': switch the oled display if present OFF (dflt ON)
  • 'S': stop processing (to do: put node to deep sleep)
  • 'i'-value : change the sample interval time to value seconds (dflt: 5 minutes)
  • 'd' or 'D': turn dust sensor calibration OFF or ON
  • 'm' or 'M': turn meteo sensor calibration OFF or ON
  • 'w' or 'W': turn dust sensor to weight modus
  • '#': turn dust sensor to partical count modus (if dust sensor supports it)
  • to be extended e.g. meta updateMin and updateMax information frequencies.

Meta information

The PyCom MySense kit will send on start and at specific updateMax (default 6 hours) intervals kit information (type of used sensors) and GPS location separately from the data stream to the data concentrator (LoRa port 3). If the GPS modules is installed the controller will (re)sent this location information at the moment (updateMin: dfault minimal frequency is 7 minutes) a location change is detected (default 50 meters).

PyCom programming

The PyCom boards are using MicroPython (see http://docs.micropython.org/en/latest/pyboard/). MicroPython is an embedded Python 3 alike scripting language.

A guide to set up (your first steps with the Pycom module) the PyCom Lopy is available from the PyCom website: Getting Started". Make sure to install the latest PyCom firmware. Try to print 'Hello World' from micro python >>> print("Hello World"), blink the RGB led and erase/cleanup the PyCom `/flash' file system.

WiFi SECURITY

Default the PyCom board will enable WiFi as Access Point with standard public known access passwords en telnet/ftp credentials. MAKE SURE you change this to avoid the use of the controller by anyone. See how to's:

How to connect the PyCom to your own network (defeat: you will ONLY be able to control the PyCom from remote within the range of your wifi). Hint: only change ftp/telnet user/password ...

Create a boot.py file with the following content:

    import os
    import machine
    import network
    import time
   
    # Duplicate output on UART
    uart = machine.UART(0, 115200)
    os.dupterm(uart)
  
    # Disable telnet and FTP server before connecting to the network
    server = network.Server()
    server.deinit()
   
    # Connect to WLAN
    wlan = network.WLAN()
    wlan = network.WLAN(mode=network.WLAN.STA)
    nets = wlan.scan()
    for net in nets:
      if net.ssid == '<YOUR OWN PYCOM ssid>':
        wlan.connect(net.ssid, auth=(net.sec, '<YOUR WiFi wireless-password>'),
          timeout=5000)
      while not wlan.isconnected():
        machine.idle() # save power while waiting
  
    # Enable telnet and FTP server with new settings
    server.init(login=('<YOU/user>', '<YOU/password>'), timeout=600)
    time.sleep(10) # Wait 10 seconds before continuing

And load up via FTP the boot.py to the board.

How to interact with the PyCom board?

Install atom from http:atom.io (PyCom): for Debian systems download the IDE application with extension .deb and install via dpkg -i atom-XYZ.deb and the pymakr plugin from the PyMakr github: git clone https://github.com/pycom/Pymakr (read the README.md!), optionally install apm, and run in the cloned directory apm install. Copy all contents to a new directory ~/.atom/packages/PyMakr. This will install a PyCom board IDE (development tooling).

Or use an alternative rshell (Python 3 tool)from: https://github.com/dhylands/rshell. Read the rshell README file how one can use this command line tool to upload, download and use REPL.

The PyCom controller will run on power ON /flash/boot.py' and /flash/main.py. If not you can interact via atom with the controller. In the directory /flash` ('home' directory) your scripts should reside. Push and keep it pushed the user button on the expansion board first and while pushing push the reset button on the controller will reboot the controller but will not run boot.py as well main.py. The other way is to press C on the keypboard (keyboard interrupt).

In the PyCom folder you will see some main scripts. The libraries for the sensor modules are in the lib folder. Copy the main scripts to the 'LoRa/firmware' directory, as well the needed libraries (see the statement import in the used scripts) to the lib directory. Point atom as new project to the configured firmware directory and press 'sync' or 'reload' button to load the files into the PyCom controller.

The PyCom board can be accessed to change the firmware either via WiFi (see the lopy-191228 PDF's and PCB manufacturer zip documentation; Contributed by Ad de Jong) and/or USB of the PyCom expansion board. To monitor the power level of the battery powered by a solar panel there is a tiny board available which guard overload of the battery and drain of the battery. The regulator switches between 3.2V and 3.8V. See technical schema and zip documentation pwrsafe1.jpg and pwrsafe1.zip (contributed by Ad de Jong).

  • Debian: make sure you have access to /dev/ttyACM0 or /dev/ttyUSB0. Use the Linux command lsusb and see if Microchip Technology, Inc. is present. If not see what the problem might be via /var/log/syslog. In one occation we had to do create the /etc/udev/rules.d/49-micropython.rules with the content:
# idVendor=04d8, idProduct=ef98 PyCom
ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="ef98", ENV{ID_MM_DEVICE_IGNORE}="1"
ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="ef98", ENV{MTP_NO_PROBE}="1"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="ef98", MODE:="0666"
KERNEL=="ttyACM*", ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="ef98", MODE:="0666"

Disconnecet the PyCom USB cable, issue sudo udevadm control --reload-rules and reconnect the USB cable to the expansion board.

MySense satellite sensor kits

The MySense satellite sensor kits are less powerfull and build around the Marvin and PyCom ESP controllers. The PyCom scripts have the following structure:

  • sensor module scripts which reside in the lib folder
  • Config.py which describes which module is used and how it is wired. It is used by the other scripts
  • sensor test scripts named as {meteo,dust,gps,ssd1306}_test.py for testing the harware
  • the main script MySense.py for operational use.

tested MySense sensor modules

Choose one meteo and one dust sensor: MySense modules in development are:

  • Sensirion SHT31 meteo: temp and humidity on I2C bus
  • Bosch BME280 meteo: temp, humidity and pressure on I2C bus
  • Bosch BME680 meteo: temp, humidity, pressure and air quality on I2C bus One serie of BME680 I2C/TTL modules are causing I2C bus errors. Advantage of BME680 is the gas (AQI) sensor as gas indication.
  • Plantower PMS7003/PMSx003 (indoor and outdoor version) dust mass and count: PM1, PM2.5 and PM10 on UART TTL (no USB)
  • Nova SDS011 dust mass only: PM2.5 and PM10 on UART TTL (no USB)
  • Sensirion SPS30 dust mass and count: PM1, PM2.5, PM4 and PM10 on UART/I2C
  • GPS location: UART TTL (no USB)
  • SSD1306 tiny oled display: 128X64 pixels on GPIO bus or I2C (preferred) bus.
  • LoRaWan: using TTN MQTT server
  • MQTT via WiFi: not implemented yet

Comment: do not use eg UART Rx on pin 12. Pin 12 high on reset will cause to omit executing boot.py and main.py. Maximum of UART modules is 2 (e.g. dust and GPS modules).

To test I2C wiring use the following EXP commands:

    SDA='P23'
    SCL='P22'
    from machine import I2C
    i2c = I2C(0,I2C.MASTER,pins=(SDA,SCL))
    i2c.scan()

This should return the I2C registers as e.g. [60] (decimal!) for the I2C address of a BME280. If [] there is no I2C module attached to the pins. Or if it hangs wiring is wrong. If the scan produces unexpected extra register address values please check your I2C modules to avoid I2C bus errors.

From release version 3 MySense will auto detect I2C devices on maximal 3 I2C busses.

wiring PyCom <-> devices

Advised is to use strict colors: red for 5V, orange for 3V3 and black for Ground. Use white (SCL or controller Rx) and yellow (SDA or controller Tx) for data wires. We use Grove connectors with female Dupont connectors. Our connector board has Grove sockets which lead to the right pins of the PyCom controller: TTL (5V or 3V3) and I2C devices (3V3).

Uart or TTL devices

E.g. GPS (3V3) and dust sensors (5V). Examples:

    GPS 3V3, Tx yellow wire - PyCom Rx Pin P10 (unused)
             Rx white wire  - PyCom Tx Pin P11
    Dust 5V, Tx yellow wire - PyCom Rx Pin P3
             Rx white wire  - PyCom Tx Pin P4
'''
The PyCom has P0 Tx pin and P1 Rx pin (expansion board USB connected) for a 3rd TTL e.g. Spec TTL NO2 sensor. To Do: add Spec gas sensor driver.

MySense support auto UART device recognition for GPS and dust sensors (SDS011, PMSx007 serie, and SPS30). See the `Config.py` file for details how to enable/disable ato configuration.
The UART pins may be defined (tuples: (white wire Tx,yellow wire Rx) -> device (Rx,Tx)) if not default pins (P4,P3),(P11,P10) are used.

#### I2C for sensors and oled display
All I2C are parallel in this example. SDA is I2C data wire, SCL is I2C clock wire.

device 3V3, SDA white wire  PyCom SDA Pin P23
            SCL yellow wire PyCom SCL Pin P22

MySense will scan the I2C bus(ses) for auto configuration of known I2C devices (oled display and various meteo sensors). I2C pins are defined as tuples (white wire SDA, yellow wire SCL), default: (P23,P22).

## remarks
BME280 or BME680 meteo sensors are tuned for indoor applications. Lifetime of sensors differ much because of this. The DHT11 or DHT22 are worse for outdoor application usage and should not be applied.
An alterrnative is to use the Sensirion SHT21 or SHT31 I2C module (only temp and RH). The SHT sensor seems to cause I2C bus errors regularly.

The dust sensors have a fan and laser. Both have a limited time of life. Hence the fan and laser are powered off in idle state. It is unclear if this method will help to improve the lifetime.

To Do: auto detect UART devices.

### RTC clock
MySense will use GPS to initilyse the Real Time Clock module. Every time the GPS location is looked up the RTC clock will be updated automatically.
This will allow MySense to timestamp measurements more precise.

### MySense satellite LoRa kit configuration
Use the file `Config.py` to define which sensors are configured for the kit. Have a good look at the *pin*s definitions and bus used for the sensor. The `Config.py` file should reside in the *firmware* directory in order to upload it to the controller.

If `dev_eui, app_eui and app_key` is defined in `Config.py` the LoRaWan On The Air Authentication (OTAA) method will be tried first to join with 4 X 15 secs a wait for authorisation.
If not defined or the join did not complete the ABP method will be used with the configured `dev_addr, nwk_swkey and app_swkey` in `Config.py`. With method ABP MySense will not wait for authorisation.

The file `Config.py` will show default configuration items in comments. Make sure to define the correct LoRa (The Things Network) keys.

In order to support solar panel as energy source MySense supports the *deepsleep* functionality. In order to do so there are 3 ways to keep the configuration details:
* `Config.py` to allow a clean cold start (powerup boot).
* `a json file in flash memory` to keep track of stable configurations and discovered devices. This allows mainly a warm reboot from eg a deepsleep.
* `nvs ram` values to survive a powercycle e.g. LoRa keys and counters, different alarm settings.

The auto maintained configuration data can be cleared as followed:
```python
    import pycom
    # 0 for clear flash configuration and nvs ram variables on cold (re)boot
    # as well clear all nvs ram variables
    pycom.nvs_set('modus',0)
    # modus 1: for clear ttl/i2c device conf
    # modus 2: do not clear assembled configuration (advised)

The json configuration will be updated if via remote command the configuration item is changed. So the change will survive a reboot.

Configuration item power will define if between deepsleeps de bus will be unpowered. E.g. deactivate GPS device fully. The kit will go into deepsleep if AND deepsleep pin is enabled AND power attribute sleep is True. On a cold boot with deepsleep pin enabled the default startup power configuration will be with ttl, i2c and sleep defined as True.

Configuration dictionary interval will define e.g. sample times ('sample': dflt 1 minute), and interval timings ('interval': dflt 15 minutes). As well next time meta information ('gps': 'gps_next', 'info': 'info_next': xyz_next values will be stored in nvs ram to survive a reboot) will be sent or GPS will be tried to find GPS location and set day time. Configuration dictionary 'power' will define, True is power off, to enable/disable power on 'ttl' (dflt: False), 'i2c' (dflt: False), 'led' (rgb led) (dflt: False), 'wifi' (dflt: True) and 'display' (dflt: False). As well 'sleep' to enable (dflt: False) a soft deepsleep (without sleep pin use). Using remote LoRa commands one may change this at run time (see MySense.py CallBack routine for details).

Alternate WiFi AP SSID and PASS can be configured via Config.py configuration file. Default SSID MySense-HHHH with PASS www.pycom.io. With a cold reboot (power cycle) and with WiFi power management off (False) the configured password will be effectuated after 1 hour. Unless 'power' item 'wifi' is defined as True. In which case the WiFi will be turned off.

Configuration dictionary 'calibration' will define Taylor calibration rules for corection of 'temperatue', 'humidity', 'pressure', 'gas', 'pm1', 'pm25', pm10', and define 'gas_base' for AQI calculations.

Use of Dext or Dexplicit (default False) will cause dust count values to be taken as inclusive previous size (Sensirion style or valuation; and cause average grain size to be calculated). True will; define Plantower style of valuation (sizes biger as underbound).

There is a wealth of configuration possiblities. Not all have been tested. See the scripts to see what they are about.

LoRa keys and package counter (important for ABP LoRa connectivity) are saved and maintained in nvs memory. As well last gps location and next meta info and next gps location check are kept in nvs memory.

How To clear the configuration in flash memory: on a cold reboot with deepsleep pin enabled and no accu attached to accu load management pin the json configuration file (dflt: MySenseConfig.json) in flash memory will be cleared and a new configuration will be detected. Use this procedure when new keys of sensors are attached to the controller.

Deepsleep ESP problem? In our experience we discovered with deepsleep: the LoPy would not wake up at a random deepsleep calls. This might be a bug in the ESP hardware or software. A work around seems to be delay for 500 msecs the ESP. This work around is under investigation.

Question: how can I force a deepsleep without an accu attached to the kit? Answer: start without the deepsleep pin enabled. After trhe first interval install then the deepsleep pin.

Testing hardware

MySense has provided several simple XYZ_test.py python scripts to test the sensor modules for needed libraries and check of wiring. Make sure to configure the right pin ID's in Config.py configuration file for the test scripts. Default pins are defined as follows:

  • I2Cpins: 'P23' (SDA, white), 'P22' (SCL, yellow) and 'P21' (dflt None, Pwr enable/disable)
  • UARTpins: TTL3 ('P1' Rx yellow, 'P0' Tx white, 'P20' (dflt None) Pwr), TTL2 ('P4' Rx yellow, 'P3' Tx white, 'P19' (dflt None) Pwr), and TTL1 ('P11' Rx white, 'P10' Tx yellow, 'P9' (dflt None) Pwr). Tx/Rx is controiller side. At devices side Tx is yellow, and Rx is white wire.
  • other pins: 'P17' and ground for keeping track of accu voltage. And 'P18' so called deep sleep pin (force deepsleep).

Test your setup one by one before trying out the main wrapper MySense.py via MySense.runMe() or main.py. A more detailed readme about the way MySense.py and other test script maybe of help can be found in the file README.MySense.md.

Your First Steps

  • visit the PyCom.io website and follow the installation guide The following is an outline how we do the developments and module testing:
  • Add the expansion board to the PyCom LoPy or WiPy module. Make sure about the orientations.
  • hook up the module (USB or via wifi) to your desktop and upgrade the firmware.
  • disconnect the expansion/PyCom module from power and only wire up one module.
  • Install hardware and sonfware one by one: say the first one is XXX (e.g. BME280)
  • copy the dependent XXX_test.py, Config.py and library module XXX.py to resp. XxPy/firmware and XxPy/firmware/lib.
  • adjust the Config.py for the right pin setup wiring. And check this twice.
  • Click on the Upload button of atom to load the scripts into the PyCom module. This will synchronise all files in the firmware directory of your desktop with the PyCom ESP controller.
  • fireup XXX_test as follows:
>>>import XXX_test

  • if not successfully copy/paste the statements of XXX_test.py one by one via atom REPL.

  • on success do the next module e.g. PMS7003 wiring and redo the test cycle.

  • on success try out MySense.py and finally install main.py:

    import MySense
    MySense.runMe()
  • and give feedback

MySense scripts

The main micropython script which drives the sensor kit is MySense.py. Use main.py to import MySense.py and run MySense.runMe() to run the kit.

The micropython (looks like Python 3) script uses the Adafruit BME280 and BME680 (I2C-bus) python module, SDS011 (Uart 1) module from Rex Fue Feinstaub https://github.com/rexfue/Feinstaub_LoPy and Telenor weather station https://github.com/TelenorStartIoT/lorawan-weather-station and SSD1306 (Adafruit tiny display SPI-bus).

In the test phase one should not download main.py to the LoPy controller. Use MySense.py in this phase instead and rename it to main.py later. Use (open) the directory firmware as base for the atom project and upload all file by pressing the upload key. On the console prompt >>> use the following:

import MySense
MySense.runMe()

After this initial test rename MySense.py to main.py. And upload main.py to the LoPy.

I2C bus errors

The I2C together with SPI will cause I2C bus errors. After using the SPI SSD1306 display before the I2C bus can be used initialize the I2C bus first.

how to reset the controller

You can delete old firmware using the instruction by PyCom. Usualy you only need to delete all uploaded file as follows:

Use the reset button on the LoPy to get the atom prompt >>> and do the following:

    import os
    os.mkfs('/flash')

And upload your new files.

How to delete or enable previous firmware? Connect Pin P12 to 3V3: 1-3 sec (safe boot), 4-6 secs (previous user update selected), 7-9 secs (safe boot factory firmware). P2 - Gnd low level bootloader (needed to update factory firmware upgrade).

The controller can always be reached via the network. Upload wifi (www.pycom.io) an empty main.py into flash folder with ftp (insecure version) ore filezilla (MacOs; can take some minutes to establish connection) in passive mode to 192.168.4.1 and user/pass micro/python to obtain access via telnet (or netcat) or USB.

test PyCom controller

The PyCom will initiate the wifi. Use Wifi AO with pass: www.pycom.io and telnet (192.168.4.1) access user/password micro/python.

Make sure you have to upgrade the PyCom controller first. However upgrading LoPy-4 failed somehow.

Simple test to silence the blue flashing, at the prompt >>>:

    import pycom
    pycom.heartbeat(False) # silence the blue flash
    pycom.rgbled(0x99ff55) # some color
    pycom.rgbled(0x000000) # led OFF

MySense controller status

The console will print status as will the flashing led on the LoPy will flash different collors: red to establish LoRa connectivity, blue when LoRa is ready, green when measuremnts are arriving, and blue when data is sent, and white when SDS011 fan is turned off to save the fan and laser as well LoPy is in idle state. LoPy will send every 5 minutes (sleep_time) a measurement sample to the TTN data concentrator.

controller wiring

See for examples of wiring the README.LopY.md (LoRaWan TTN, BME280, SDS011 and SSD1306) or README.WiPy.md (wifi MQTT, BME680, PMS7003, SSD1306) readme's.

Its is handy to use a 'connector board': a simple PCB which has a row of say Grove connectors for the sensor devices and 'foot' for the LoPy controller. The electronic scheme using mosfets to power sensor devices and ready scheme to send to a board producer can be found in the documentation directory.

ATTENTION: we discovered that the wifi beacon is causing in some circumstances a 2ms drop of the power to the ESP8266 controller below 3.3V every 100ms interval. Some dust laser sensors are influenced and produce unexpected high measurements because of this. Suggested is to use a good powerfull adapter, and/or apply a 1000 uF capacitor or configure MySense to switch off the wifi after one hour (see Config.py for a how to).

To Do

Add more sensor modules. The Shiney PPD42NS (unreliable and too much errors), DHT22 and DHT11 (too much peaks and outdoor time to live too short) meteo sensor are depricated. Sensirion SHT31 (only temperature and RH, not very precise). Note: The Plantower PMS7003 and SPS30 are much smaller and consume less energy as the Nova SDS011 (but it has a nice air inlet). The Plantower PMSx003 has a detachable fan, air tube inlet, cleanable inlet, and is more robust for outdoor application.

Licensing

If not noted the scripts and changes to external scripts are GPL V3.

some references