elomagic/weather-station-client-mpy

Weather Station Client for ESP8266 Micropython

DIY Weather Bot

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Table of Contents

• What about?
• Hardware component list
• Preparing ESP
• Configuration
  • Configuring Bot
• LED Codes
• Hardware Example
  • Circuit diagram
  • PCB
  • Case
• Known issues

What about?

This project is a part of my "small" DIY project about to build up a weather station mesh.

This part deals with the weather client, which measures temperature, air pressure and humidity and transmits them to any REST server or MQTT broker.

The part with the REST server is described in another project. See here ... TODO

Hardware component list

Option A

Cheapest and simplest solution. The client will be powered by an external USB power supply.

Component list

• ESP8266 with at least 2MB flash memory and installed MicroPython image (2MiB+ flash version > https://micropython.org/download/?port=esp8266)
• BMP280 (w/o humidity sensor) or BME (with humidity sensor)

Option B

The solution is powered by an external rechargeable battery.

Component list

In addition to the components from option A, the following components are required

• tbd.
• ...
• ...

Optional

tbd.

Prepare Hardware

Before you can start by configuring your bot, you have to upload the firmware. Recommendation is, that MicroPython is successful running on your ESP.

(TODO) Install "ampy"

Upload the projects files with the following command

./build.py --port COM6 --baud 115200 build deploy

Configure Bot

The weather bot support two configuration options.

Option A - Via console by using USB connection

Configuration file

# SSID of the access point
wifi.ssid=ssid
# Password of the access point
wifi.password=changeit
# IP address of this client when access point doesn't provide dynamically IP address. Usually empty
wifi.address=
# Usually empty (By default 255.255.255.0)
wifi.netmask=255.255.255.0
# Usually empty
wifi.gateway=
# Usually empty (By default 8.8.8.8)
wifi.dns=8.8.8.8
# Name of client bot (By default 'Weather-Bot')
wifi.clientName=[BOT_NAME]

# Unique identifier of this client ( Looking for a generator. See https://www.uuidgenerator.net/version4 )
sensor.uid=uuid
# Measure interval in seconds (By default 300 seconds)
sensor.measureInterval=300

# REST or MQTT URL server address.  Sample "http://192.168.150.2/rest" or "mqtt://192.168.150.2/kitchen"       
server.url=http://[HOSTNAME]/rest
# Application key to authentication
server.appKey=

# Debug level  (By default debug)
logging.level=debug
# Controls logging output to the console (By default enabled, 1 = Enabled, 0 = Disabled)
logging.console.enabled=1
# Controls logging output to file on the ESP (By default disabled, 1 = Enabled, 0 = Disabled)
logging.file.enabled=0

Command to read configuration from ESP

.\Setup-Client.py read --port COM7 --file configuration.properties

Command to write configuration to ESP

.\Setup-Client.py write --port COM7 --file configuration.properties

Note: The commands work most reliably if you execute them shortly after a bot reset!

Option B - Via Web UI of the weather bot

• Power on ESP
• Connect the ESP via Wi-Fi. Look for the SSID "Weather-Bot". Password is "weather-bot".
• The configuration page appears. Configure the bot according to your needs.

LED Codes

The LED gives feedback on successful and faulty communication.

Please ignore the very short flash when counting. Each flash is min. half a second long

Count	Description
0	Worst case. We have to investigate
1	Data successfully transmitted
2	Entering setup
3	Unable to connect to access point
4	Unable to post data to server
5	Unable to connect NTP server
6	Unexpected error
7	HTTP authentication failed

Weather Client Data Model

The weather-bot support two communications protocols.

HTTP communication

The following examples shows which data is transmitted:

HTTP Command

POST /rest/measure HTTP/1.1
Host: weather-server.local

Payload

{
    // UID of the measure sensor
    "sensorUid": "892ed1a5-a416-418d-b478-78d7ff744b2e",
    // UNIX epoch timestamp of the measurement in seconds 
    "unixEpochTimestamp": "1656914554",
    // Measured temperature 
    "temperature": "31.52",
    // Unit of the measured temperature 
    "temperatureUnit": "°C",
    // Measured pressure
    "pressure": "999.49",
    // Unit of the measured pressure
    "pressureUnit": "hPA",
    // Measured humidity in percent
    "humidity": "33.8064",
    // Battery voltage (Unit must be 'V')
    "batteryVoltage": "3.3"
}

MQTT communication

Topic generation rule: /[Path of the URL]/[Sensor UID][Property Name]

Examples:

• kitchen/892ed1a5-a416-418d-b478-78d7ff744b2e/temperature
• kitchen/892ed1a5-a416-418d-b478-78d7ff744b2e/humidity
• garden/17356968-d9cd-4c50-9afd-1a7fb1972a5e/humidity

Published measures

• "temperature" - Measured temperature in celsius grad (°C)
• "pressure" - Measured pressures in hecto pascal (hPa)
• "humidity" - Measured humidity in percent
• "batteryVoltage" - Measured battery voltage in voltage (V)

Circuit diagram

Printed Circuit Board

Following PCB was made with EasyEDA.

Device Case Proposal

Proposal of a device case. Made with Blender.

Known Issues

• TLS (HTTPS) communication doesn't work

Outlook - Possible further ideas

• TLS support (This will be very difficult to impossible. TLS needs a lot of memory and the ESP8266 has not enough of it.)