main.cpp File Reference

ESP32 Smart Thermostat with TFT Display and Blynk Integration. More...

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>
#include <TFT_eSPI.h>
#include <DHT.h>

Macros
#define	BLYNK_TEMPLATE_ID   "TMPLxxxxxxxxx"
#define	BLYNK_TEMPLATE_NAME   "My Thermostat"
#define	BLYNK_AUTH_TOKEN   "AbCdEfGhIjKlMnOpQrStUvWxYz123456"
#define	RELAY_PIN   26
#define	SENSOR_PIN   15
#define	SENSOR_TYPE   DHT11
#define	BACKLIGHT_PIN   13
#define	RELAY_ON   LOW
	Relay Logic configuration. CW-020 Relays are usually Low-Level Trigger, meaning pulling the pin to GND turns the relay ON.
#define	RELAY_OFF   HIGH
#define	COLOR_PANEL_BG   TFT_BLACK
#define	COLOR_PANEL_FROST   0x2104
#define	COLOR_HEATING   0xFB00
#define	COLOR_HUMIDITY   0x3DFF
#define	COLOR_GREY_TEXT   0x8410
#define	COLOR_TEXT_WHITE   TFT_WHITE

Functions
DHT	dht (SENSOR_PIN, SENSOR_TYPE)
	BLYNK_WRITE (V2)
	Blynk App Callback: Target Temperature Slider. Triggered automatically when the user changes the slider on the Blynk App (Virtual Pin 2).
	BLYNK_WRITE (V4)
	Blynk App Callback: Emergency Stop Button. Forces the relay to turn off if the button on Virtual Pin 4 is pressed (value goes to 0).
void	setup ()
	Standard Arduino Setup Function. Initializes hardware pins, display, sensors, and network connections.
void	loop ()
	Standard Arduino Loop Function. Kept clean. Only processes Blynk cloud tasks and hardware timers.
void	readSensorAndControl ()
	Core Application Logic. Reads the DHT sensor, applies calibration offsets, updates the cloud, checks the thermostat rules, and triggers a UI redraw if any data changed.
void	checkThermostat ()
	Evaluates the current temperature against the target setpoint. Uses hysteresis to define a "deadband" so the relay doesn't rapidly click on and off when the temperature hovers exactly at the target.
void	drawInterface ()
	Renders the Graphical User Interface on the TFT display. Draws the central circle, dynamic sidebar, icons, and text.

Variables
char	ssid [] = "YOUR_WIFI_SSID"
char	pass [] = "YOUR_WIFI_PASSWORD"
TFT_eSPI	tft = TFT_eSPI()
BlynkTimer	timer
float	currentTemp = 0
float	humidity = 0
float	targetTemp = 22.0
float	hysteresis = 0.5
bool	isHeating = false
float	lastTemp = -999
float	lastHumidity = -999
float	lastTarget = -999
bool	lastHeatingState = !isHeating
bool	forceRedraw = true
const unsigned char icon_drop[]	PROGMEM
	XBM Image Data for the Humidity Drop. The PROGMEM keyword forces the microcontroller to store this array in Flash memory instead of RAM, leaving more RAM available for dynamic variables.

Detailed Description

ESP32 Smart Thermostat with TFT Display and Blynk Integration.

• This firmware reads environmental data from a DHT sensor, controls a heating relay based on a target setpoint with hysteresis, and displays a dynamic, anti-flickering user interface on an SPI TFT screen.

Macro Definition Documentation

BACKLIGHT_PIN

#define BACKLIGHT_PIN   13

BLYNK_AUTH_TOKEN

#define BLYNK_AUTH_TOKEN   "AbCdEfGhIjKlMnOpQrStUvWxYz123456"

BLYNK_TEMPLATE_ID

#define BLYNK_TEMPLATE_ID   "TMPLxxxxxxxxx"

BLYNK_TEMPLATE_NAME

#define BLYNK_TEMPLATE_NAME   "My Thermostat"

COLOR_GREY_TEXT

#define COLOR_GREY_TEXT   0x8410

COLOR_HEATING

#define COLOR_HEATING   0xFB00

COLOR_HUMIDITY

#define COLOR_HUMIDITY   0x3DFF

COLOR_PANEL_BG

#define COLOR_PANEL_BG   TFT_BLACK

COLOR_PANEL_FROST

#define COLOR_PANEL_FROST   0x2104

COLOR_TEXT_WHITE

#define COLOR_TEXT_WHITE   TFT_WHITE

RELAY_OFF

#define RELAY_OFF   HIGH

RELAY_ON

#define RELAY_ON   LOW

Relay Logic configuration. CW-020 Relays are usually Low-Level Trigger, meaning pulling the pin to GND turns the relay ON.

RELAY_PIN

#define RELAY_PIN   26

SENSOR_PIN

#define SENSOR_PIN   15

SENSOR_TYPE

#define SENSOR_TYPE   DHT11

Function Documentation

BLYNK_WRITE() [1/2]

BLYNK_WRITE

(

V2

)

Blynk App Callback: Target Temperature Slider. Triggered automatically when the user changes the slider on the Blynk App (Virtual Pin 2).

BLYNK_WRITE() [2/2]

BLYNK_WRITE

(

V4

)

Blynk App Callback: Emergency Stop Button. Forces the relay to turn off if the button on Virtual Pin 4 is pressed (value goes to 0).

checkThermostat()

void checkThermostat

(

)

Evaluates the current temperature against the target setpoint. Uses hysteresis to define a "deadband" so the relay doesn't rapidly click on and off when the temperature hovers exactly at the target.

dht()

DHT dht	(	SENSOR_PIN	,
		SENSOR_TYPE	)

drawInterface()

void drawInterface

(

)

Renders the Graphical User Interface on the TFT display. Draws the central circle, dynamic sidebar, icons, and text.

loop()

void loop

(

)

Standard Arduino Loop Function. Kept clean. Only processes Blynk cloud tasks and hardware timers.

readSensorAndControl()

void readSensorAndControl

(

)

Core Application Logic. Reads the DHT sensor, applies calibration offsets, updates the cloud, checks the thermostat rules, and triggers a UI redraw if any data changed.

setup()

void setup

(

)

Standard Arduino Setup Function. Initializes hardware pins, display, sensors, and network connections.

Variable Documentation

currentTemp

float currentTemp = 0

forceRedraw

bool forceRedraw = true

Forces a full screen wipe and redraw on the first boot cycle

humidity

float humidity = 0

hysteresis

float hysteresis = 0.5

Temperature gap to prevent rapid relay switching

isHeating

bool isHeating = false

lastHeatingState

bool lastHeatingState = !isHeating

lastHumidity

float lastHumidity = -999

lastTarget

float lastTarget = -999

lastTemp

float lastTemp = -999

pass

char pass[] = "YOUR_WIFI_PASSWORD"

PROGMEM

const unsigned char icon_flame [] PROGMEM

Initial value:

                                      = {
  0x00, 0x00, 0x00, 0x01, 0x80, 0x03, 0xc0, 0x07, 0xe0, 0x0f, 0xf0, 0x1f,
  0xf8, 0x3f, 0xfc, 0x7f, 0xfe, 0x7f, 0xfe, 0x7f, 0xfe, 0x3f, 0xfc, 0x1f,
  0xf8, 0x0f, 0xf0, 0x03, 0xc0, 0x00, 0x00, 0x00
}

XBM Image Data for the Humidity Drop. The PROGMEM keyword forces the microcontroller to store this array in Flash memory instead of RAM, leaving more RAM available for dynamic variables.

XBM Image Data for the Heating Flame.

ssid

char ssid[] = "YOUR_WIFI_SSID"

targetTemp

float targetTemp = 22.0

tft

TFT_eSPI tft = TFT_eSPI()

timer

BlynkTimer timer