Weather display for M5Stack Core2

Weather station displaying the latest readings received via MQTT and displaying numerical ICM UW weather forecast.

The software has been written for the M5Stack Core2 board, but should work on other similar boards with little or no adaptation needed.

The main screen displays temperature, humidity, and air pressure from readings received via MQTT. Forecast plot screens are accessible by touching the screen.

• Touch the temperature area to display the temperature forecast: ( mean air temperature, min-max air temperature, wind chill temperature, and surface temperature).
• Touch the humidity area to display the precipitation forecast: ( rain, snow, and rain and snow mixed).
• Touch the air pressure area to display the air pressure forecast.

MQTT messagge format

The application expects the MQTT message be in a JSON object containing temperature in °C, humidity in percents, and pressure in hPa, as in the example below. Other fields are ignored.

{
  "battery": 83,
  "humidity": 88.52,
  "linkquality": 54,
  "power_outage_count": 1015,
  "pressure": 981.3,
  "temperature": 4.54,
  "voltage": 2975
}

Screenshots

Main screen

Temperature forecast	Precipitation forecast	Air pressure forecast

Configuration

Create settings-private.hpp file that defines:

• WIFI_SSID and WIFI_PASSWORD,
• MQTT_SERVER, MQTT_TOPIC plus optionally any of: MQTT_PORT (default: 1883), MQTT_USER and MQTT_PASSWORD (both default to null), MQTT_CLIENT_NAME_PREFIX (default: M5Stack Core2),
• FORECAST_LAT and FORECAST_LON plus optionally ALTITUDE (to calculate soft min and max of the pressure graph, default: 0),
• optionally TZ in the POSIX format (default: UTC),
• optionally LANG (default: LANG_EN), described below.

Example settings-private.hpp configuration file:

#pragma once

#define WIFI_SSID "YourWiFiSSID"
#define WIFI_PASSWORD "YourWiFiPassword"

#define MQTT_TOPIC "zigbee2mqtt/outside"

#define FORECAST_LAT 52.247308
#define FORECAST_LON 21.013342
#define ALTITUDE 105

#define TZ "CET-1CEST,M3.5.0,M10.5.0/3"
#define LANG LANG_PL

Language support

Poor man's locale support is added for time formatting. The time string is the local name of the weekday, followed by the time formatted by strftime in the C locale. The Lang class constructor takes eight c-strings - seven weekday names and the strftime format string for the rest of the format. E.g., Spanish could be defined as Lang("dom", "lun", "mar", "mié", "jue", "vie", "sáb", ", %d/%m %H:%M").

Two languages are pre-defined in the code: English and Polish.

#define LANG_EN Lang("", "", "", "", "", "", "", "%a, %b %d %I:%M %p")
#define LANG_PL Lang("nd.", "pn.", "wt.", "śr.", "czw.", "pt.", "sb.", ", %d.%m %H:%M")