Simple Weather Station

In this project, we show a simple Weather Application, using ESP32 and OLED. A simple OLed display shows the current temperature and the humidity using the DHT11 sensro and thean attached button works as the user interaction to the application.

1. Button Click: Change temperature representation
2. Button Clicks: Show Simple Animation
3. Seconds Click: Turn monitor off/on

Button

To implement button on_click the GPIO_INTR_POSEDGE was used to interrupt on up edge of the click, as wrote in lib/button/button.c. In the hardware, we have a Push Button with 10K pull down resistor (Using 2 20K parallel), so when the button is pressed, the MCU gets a HIGH voltage. The Main application polls the button to see if the flag was changed in order to debounce it and call the on_click function.

Animation

The animation is implemented using "tick". Every call by the main proccess updates the animation accordingly to the current time. This could be used to update an 2D Physics engine and use sprites to update the display.

Main and Aplication Flow

The main file controls the application flow. We have 2 "Threads": The main thread polls button values, ticks the animation and show DHT11 informations in the OLed Screen; The weather Thread, runs at every 500ms reading from DHT11 hardware and assign the values to a common variable, so the main thread can read it and show in the display.

Circuit Diagram

Harware Circuit

Schematic Circuit

1 Click - Change Representation

The Temperature representations is changing between °C, °F and K.

2 Clicks - Show Animation (Changes application behaviour)

Every 2 Clicks the ball animations is shown.

3 Seconds Click - Turns the OLed display off (Power saver)

On 3 Seconds click the screen is turn off to save battery life, turning on again when pressed for three seconds.

Documents about interrupt in ESP32

• https://circuitdigest.com/microcontroller-projects/esp32-timers-and-timer-interrupts
• https://docs.espressif.com/projects/esp-idf/en/v4.3/esp32/api-reference/peripherals/timer.html#timer-api-timer-initialization

References

1. SSD1306 datasheet, can be found here.
2. ESP-IDF Implementation of SSD1306 by nopnop2002, can be found here.
3. DHT11 Datasheet can be found here.
4. DHT11 Driver implementation by UncleRus, can be found here.