Exercise on ESP32 (Arduino framework) work with DHT11 temperature & humidity sensor, with display on ST7789 SPI LCD and also with BLE function.
The DHT11 (or DHT22 and similar) are cheap temperature and humidity sensors. The communicate with a uC is over a single wire.
The electric connection to the ESP32 is very simple, as the DHT series can
be powered direct with 3.3V. Only 3 wires are needed: VCC, GND and the data
line.
Important is that a 10kΩ or at least 4.7kΩ resistor is
needed between the data line and VCC. Sometimes this resistor is already
integrated in the module, sometimes its necessary to add it.
ref: https://desire.giesecke.tk/index.php/2018/01/30/esp32-dht11/
Library used:
DHT sensor library for ESPx by beegee_tokyo is used in this exercise.
To display on ST7789 SPI SPI LCD, Adafruit ST7735 and ST7789 Library and Adafruit GFX Library are used. (related: ESP32-C3/arduino-esp32 to display on ST7735 and ST7789 SPI LCDs)
Connection:
Connection between DHT11 and ESP32 (GPIO#)
-----------------------------------------------
DHT11 ESP32
----- -----
VCC* 3V3
DATA** 32
NC
GND GND
* - depends on module, my DHT11 module is 3V3~5V operate.
** - depends on your module, maybe you have to add a
pull-up resistor (~10K Ohm) betwee DATA and VCC.
Connection between ST7789 SPI and ESP32 (GPIO#)
-----------------------------------------------
ST7789 SPI ESP32
---------- -----
GND GND
VCC 3V3
SCL 18
SDA 23
RES 26
DC 25
CS 33
BLK 3V3
Exercise code:
ESP32_DHT_ST789.ino, modified from DHT_ESP32 example of DHT sensor library for ESPx, with interface to ST7789 SPI LCD.
#include "DHTesp.h"
#include <Ticker.h>
#include <Adafruit_GFX.h> // Core graphics library
#include <Adafruit_ST7789.h> // Hardware-specific library for ST7789
#include <Fonts/FreeMonoBold12pt7b.h>
#include <SPI.h>
#ifndef ESP32
#pragma message(THIS EXAMPLE IS FOR ESP32 ONLY!)
#error Select ESP32 board.
#endif
/**************************************************************/
/* Example how to read DHT sensors from an ESP32 using multi- */
/* tasking. */
/* This example depends on the Ticker library to wake up */
/* the task every 5 seconds */
/**************************************************************/
DHTesp dht;
void tempTask(void *pvParameters);
bool getTemperature();
void triggerGetTemp();
/** Task handle for the light value read task */
TaskHandle_t tempTaskHandle = NULL;
/** Ticker for temperature reading */
Ticker tempTicker;
/** Comfort profile */
ComfortState cf;
/** Flag if task should run */
bool tasksEnabled = false;
/** Pin number for DHT11 data pin */
int dhtPin = 32; //17;
#define TFT_CS 33
#define TFT_RST 26
#define TFT_DC 25
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);
bool rqsUpdate = false;
TempAndHumidity updateValues;
/**
* initTemp
* Setup DHT library
* Setup task and timer for repeated measurement
* @return bool
* true if task and timer are started
* false if task or timer couldn't be started
*/
bool initTemp() {
byte resultValue = 0;
// Initialize temperature sensor
dht.setup(dhtPin, DHTesp::DHT11);
Serial.println("DHT initiated");
// Start task to get temperature
xTaskCreatePinnedToCore(
tempTask, /* Function to implement the task */
"tempTask ", /* Name of the task */
4000, /* Stack size in words */
NULL, /* Task input parameter */
5, /* Priority of the task */
&tempTaskHandle, /* Task handle. */
1); /* Core where the task should run */
if (tempTaskHandle == NULL) {
Serial.println("Failed to start task for temperature update");
return false;
} else {
// Start update of environment data every 20 seconds
tempTicker.attach(5, triggerGetTemp);
}
return true;
}
/**
* triggerGetTemp
* Sets flag dhtUpdated to true for handling in loop()
* called by Ticker getTempTimer
*/
void triggerGetTemp() {
if (tempTaskHandle != NULL) {
xTaskResumeFromISR(tempTaskHandle);
}
}
/**
* Task to reads temperature from DHT11 sensor
* @param pvParameters
* pointer to task parameters
*/
void tempTask(void *pvParameters) {
Serial.println("tempTask loop started");
while (1) // tempTask loop
{
if (tasksEnabled) {
// Get temperature values
getTemperature();
}
// Got sleep again
vTaskSuspend(NULL);
}
}
/**
* getTemperature
* Reads temperature from DHT11 sensor
* @return bool
* true if temperature could be aquired
* false if aquisition failed
*/
bool getTemperature() {
// Reading temperature for humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
TempAndHumidity newValues = dht.getTempAndHumidity();
// Check if any reads failed and exit early (to try again).
if (dht.getStatus() != 0) {
Serial.println("DHT11 error status: " + String(dht.getStatusString()));
return false;
}
float heatIndex = dht.computeHeatIndex(newValues.temperature, newValues.humidity);
float dewPoint = dht.computeDewPoint(newValues.temperature, newValues.humidity);
float cr = dht.getComfortRatio(cf, newValues.temperature, newValues.humidity);
String comfortStatus;
switch(cf) {
case Comfort_OK:
comfortStatus = "Comfort_OK";
break;
case Comfort_TooHot:
comfortStatus = "Comfort_TooHot";
break;
case Comfort_TooCold:
comfortStatus = "Comfort_TooCold";
break;
case Comfort_TooDry:
comfortStatus = "Comfort_TooDry";
break;
case Comfort_TooHumid:
comfortStatus = "Comfort_TooHumid";
break;
case Comfort_HotAndHumid:
comfortStatus = "Comfort_HotAndHumid";
break;
case Comfort_HotAndDry:
comfortStatus = "Comfort_HotAndDry";
break;
case Comfort_ColdAndHumid:
comfortStatus = "Comfort_ColdAndHumid";
break;
case Comfort_ColdAndDry:
comfortStatus = "Comfort_ColdAndDry";
break;
default:
comfortStatus = "Unknown:";
break;
};
Serial.println(" T:" + String(newValues.temperature)
+ " H:" + String(newValues.humidity)
+ " I:" + String(heatIndex)
+ " D:" + String(dewPoint)
+ " " + comfortStatus);
rqsUpdate = true;
updateValues = newValues;
return true;
}
void setup()
{
Serial.begin(115200);
Serial.println();
Serial.println("DHT ESP32 example with tasks");
//init DHT
initTemp();
// Signal end of setup() to tasks
tasksEnabled = true;
//init ST7789
tft.init(240, 320); // Init ST7789 320x240
tft.setRotation(3);
tft.setFont(&FreeMonoBold12pt7b);
tft.setTextWrap(true);
tft.fillScreen(ST77XX_RED);
delay(300);
tft.fillScreen(ST77XX_GREEN);
delay(300);
tft.fillScreen(ST77XX_BLUE);
delay(300);
tft.fillScreen(ST77XX_BLACK);
delay(300);
tft.setCursor(0, 0);
tft.setTextColor(ST77XX_RED);
tft.setCursor(0, 0);
tft.setTextColor(ST77XX_RED);
tft.print("\n");
tft.print("ESP32 + DHT11 + ST7789\n");
}
void loop() {
if (!tasksEnabled) {
// Wait 2 seconds to let system settle down
delay(2000);
// Enable task that will read values from the DHT sensor
tasksEnabled = true;
if (tempTaskHandle != NULL) {
vTaskResume(tempTaskHandle);
}
}
if(rqsUpdate){
tft.fillRect(10, 30, 300, 53, ST77XX_BLACK);
tft.setCursor(5, 50);
tft.setTextColor(ST77XX_WHITE);
tft.print(" temperature: " + String(updateValues.temperature));
tft.setCursor(5, 75);
tft.setTextColor(ST77XX_WHITE);
tft.print(" humidity: " + String(updateValues.humidity));
Serial.println(" T:" + String(updateValues.temperature) + " H:" + String(updateValues.humidity));
rqsUpdate = false;
}
yield();
}
/*
* Execise run on ESP32 (ESP32-DevKitC V4) with arduino-esp32 2.0.1,
* read DHT11 Humidity & Temperature Sensor,
* and display on ST7789 SPI TFT, 2" IPS 240x320, with graph.
*
* Library needed:
* - DHT sensor library for ESPx by beegee_tokyo
* - Adafruit ST7735 and ST7789 Library by Adafruit
* - Adafruit GFX Library by Adafruit
*
* Modify from examples DHT_ESP32 of DHT sensor library for ESPx
*
* Connection between DHT11 and ESP32 (GPIO#)
* -----------------------------------------------
* DHT11 ESP32
* ----- -----
* VCC* 3V3
* DATA** 32
* NC
* GND GND
*
* * - depends on module, my DHT11 module is 3V3~5V operate.
*
* ** - depends on your module, maybe you have to add a
* pull-up resistor (~10K Ohm) betwee DATA and VCC.
*
* Connection between ST7789 SPI and ESP32 (GPIO#)
* -----------------------------------------------
* ST7789 SPI ESP32
* ---------- -----
* GND GND
* VCC 3V3
* SCL 18
* SDA 23
* RES 26
* DC 25
* CS 33
* BLK 3V3
*
*/
#include "DHTesp.h"
#include <Ticker.h>
#include <Adafruit_GFX.h> // Core graphics library
#include <Adafruit_ST7789.h> // Hardware-specific library for ST7789
#include <Fonts/FreeMonoBold12pt7b.h>
#include <SPI.h>
#ifndef ESP32
#pragma message(THIS EXAMPLE IS FOR ESP32 ONLY!)
#error Select ESP32 board.
#endif
DHTesp dht;
void tempTask(void *pvParameters);
bool getTemperature();
void triggerGetTemp();
/** Task handle for the light value read task */
TaskHandle_t tempTaskHandle = NULL;
/** Ticker for temperature reading */
Ticker tempTicker;
/** Comfort profile */
ComfortState cf;
/** Flag if task should run */
bool tasksEnabled = false;
/** Pin number for DHT11 data pin */
int dhtPin = 32; //17;
//hardware SPI MOSI 23
//hardware SPI SCK 18
#define TFT_CS 33
#define TFT_RST 26
#define TFT_DC 25
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);
bool rqsUpdate = false;
TempAndHumidity updateValues;
unsigned long prvUpdateMillis;
#define FRAME_TOPX 0
#define FRAME_TOPY 200
#define FRAME_WIDTH 240
#define FRAME_HEIGHT 100
#define FRAME_BOTTOMY FRAME_TOPY + FRAME_HEIGHT
#define SCR_HEIGHT 320
int idx = 0;
#define IDX_MAX 240
/**
* initTemp
* Setup DHT library
* Setup task and timer for repeated measurement
* @return bool
* true if task and timer are started
* false if task or timer couldn't be started
*/
bool initTemp() {
byte resultValue = 0;
// Initialize temperature sensor
dht.setup(dhtPin, DHTesp::DHT11);
Serial.println("DHT initiated");
// Start task to get temperature
xTaskCreatePinnedToCore(
tempTask, /* Function to implement the task */
"tempTask ", /* Name of the task */
4000, /* Stack size in words */
NULL, /* Task input parameter */
5, /* Priority of the task */
&tempTaskHandle, /* Task handle. */
1); /* Core where the task should run */
if (tempTaskHandle == NULL) {
Serial.println("Failed to start task for temperature update");
return false;
} else {
// Start update of environment data every XX seconds
tempTicker.attach(2, triggerGetTemp);
}
return true;
}
/**
* triggerGetTemp
* Sets flag dhtUpdated to true for handling in loop()
* called by Ticker getTempTimer
*/
void triggerGetTemp() {
if (tempTaskHandle != NULL) {
xTaskResumeFromISR(tempTaskHandle);
}
}
/**
* Task to reads temperature from DHT11 sensor
* @param pvParameters
* pointer to task parameters
*/
void tempTask(void *pvParameters) {
Serial.println("tempTask loop started");
while (1) // tempTask loop
{
if (tasksEnabled) {
// Get temperature values
getTemperature();
}
// Got sleep again
vTaskSuspend(NULL);
}
}
/**
* getTemperature
* Reads temperature from DHT11 sensor
* @return bool
* true if temperature could be aquired
* false if aquisition failed
*/
bool getTemperature() {
// Reading temperature for humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
TempAndHumidity newValues = dht.getTempAndHumidity();
// Check if any reads failed and exit early (to try again).
if (dht.getStatus() != 0) {
Serial.println("DHT11 error status: " + String(dht.getStatusString()));
return false;
}
float heatIndex = dht.computeHeatIndex(newValues.temperature, newValues.humidity);
float dewPoint = dht.computeDewPoint(newValues.temperature, newValues.humidity);
float cr = dht.getComfortRatio(cf, newValues.temperature, newValues.humidity);
String comfortStatus;
switch(cf) {
case Comfort_OK:
comfortStatus = "Comfort_OK";
break;
case Comfort_TooHot:
comfortStatus = "Comfort_TooHot";
break;
case Comfort_TooCold:
comfortStatus = "Comfort_TooCold";
break;
case Comfort_TooDry:
comfortStatus = "Comfort_TooDry";
break;
case Comfort_TooHumid:
comfortStatus = "Comfort_TooHumid";
break;
case Comfort_HotAndHumid:
comfortStatus = "Comfort_HotAndHumid";
break;
case Comfort_HotAndDry:
comfortStatus = "Comfort_HotAndDry";
break;
case Comfort_ColdAndHumid:
comfortStatus = "Comfort_ColdAndHumid";
break;
case Comfort_ColdAndDry:
comfortStatus = "Comfort_ColdAndDry";
break;
default:
comfortStatus = "Unknown:";
break;
};
Serial.println(" T:" + String(newValues.temperature)
+ " H:" + String(newValues.humidity)
+ " I:" + String(heatIndex)
+ " D:" + String(dewPoint)
+ " " + comfortStatus);
rqsUpdate = true;
updateValues = newValues;
return true;
}
void setup()
{
Serial.begin(115200);
Serial.println();
Serial.println("DHT ESP32 example with tasks");
//init DHT
initTemp();
// Signal end of setup() to tasks
tasksEnabled = true;
//init ST7789
tft.init(240, 320); // Init ST7789 320x240
tft.setRotation(2);
tft.setFont(&FreeMonoBold12pt7b);
tft.setTextWrap(true);
tft.fillScreen(ST77XX_RED);
delay(300);
tft.fillScreen(ST77XX_GREEN);
delay(300);
tft.fillScreen(ST77XX_BLUE);
delay(300);
tft.setCursor(0, 0);
tft.setTextColor(ST77XX_RED);
tft.print("\n");
tft.print("ESP32 + DHT11 + ST7789\n");
prvUpdateMillis = millis();
}
void loop() {
if (!tasksEnabled) {
// Wait 2 seconds to let system settle down
delay(2000);
// Enable task that will read values from the DHT sensor
tasksEnabled = true;
if (tempTaskHandle != NULL) {
vTaskResume(tempTaskHandle);
}
}
if(rqsUpdate){
unsigned long curUpdateMillis = millis();
tft.fillRect(0, 53, 240, 75, ST77XX_BLUE );
tft.setCursor(0, 70);
tft.setTextColor(ST77XX_WHITE);
tft.print(" temp.: " + String(updateValues.temperature));
tft.setCursor(0, 95);
tft.setTextColor(ST77XX_WHITE);
tft.print(" humi.: " + String(updateValues.humidity));
tft.setCursor(0, 115);
tft.setTextColor(ST77XX_WHITE);
tft.print(" mills.: " + String(curUpdateMillis-prvUpdateMillis));
prvUpdateMillis = curUpdateMillis;
if(idx==0){
tft.fillRect(FRAME_TOPX, FRAME_TOPY,
FRAME_WIDTH, SCR_HEIGHT-FRAME_TOPY,
ST77XX_BLUE);
}
tft.drawLine(
FRAME_TOPX+idx, FRAME_BOTTOMY,
FRAME_TOPX+idx, FRAME_BOTTOMY-(int)updateValues.temperature,
ST77XX_WHITE);
idx++;
if(idx >= IDX_MAX)
idx = 0;
Serial.println(" T:" + String(updateValues.temperature) + " H:" + String(updateValues.humidity));
rqsUpdate = false;
}
yield();
}
/*
Execise run on ESP32 (ESP32-DevKitC V4) with arduino-esp32 2.0.1,
read DHT11 Humidity & Temperature Sensor,
and display on ST7789 SPI TFT, 2" IPS 240x320, with graph.
BLE function added.
Library needed:
- DHT sensor library for ESPx by beegee_tokyo
- Adafruit ST7735 and ST7789 Library by Adafruit
- Adafruit GFX Library by Adafruit
Modify from examples DHT_ESP32 of DHT sensor library for ESPx
Connection between DHT11 and ESP32 (GPIO#)
-----------------------------------------------
DHT11 ESP32
----- -----
VCC* 3V3
DATA** 32
NC
GND GND
* * - depends on module, my DHT11 module is 3V3~5V operate.
* ** - depends on your module, maybe you have to add a
pull-up resistor (~10K Ohm) betwee DATA and VCC.
Connection between ST7789 SPI and ESP32 (GPIO#)
-----------------------------------------------
ST7789 SPI ESP32
---------- -----
GND GND
VCC 3V3
SCL 18
SDA 23
RES 26
DC 25
CS 33
BLK 3V3
*/
#include "DHTesp.h"
#include <Ticker.h>
#include <Adafruit_GFX.h> // Core graphics library
#include <Adafruit_ST7789.h> // Hardware-specific library for ST7789
#include <Fonts/FreeMonoBold12pt7b.h>
#include <SPI.h>
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
#ifndef ESP32
#pragma message(THIS EXAMPLE IS FOR ESP32 ONLY!)
#error Select ESP32 board.
#endif
DHTesp dht;
void tempTask(void *pvParameters);
bool getTemperature();
void triggerGetTemp();
/** Task handle for the light value read task */
TaskHandle_t tempTaskHandle = NULL;
/** Ticker for temperature reading */
Ticker tempTicker;
/** Comfort profile */
ComfortState cf;
/** Flag if task should run */
bool tasksEnabled = false;
/** Pin number for DHT11 data pin */
int dhtPin = 32; //17;
//hardware SPI MOSI 23
//hardware SPI SCK 18
#define TFT_CS 33
#define TFT_RST 26
#define TFT_DC 25
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);
bool rqsUpdate = false;
TempAndHumidity updateValues;
unsigned long prvUpdateMillis;
#define FRAME_TOPX 0
#define FRAME_TOPY 200
#define FRAME_WIDTH 240
#define FRAME_HEIGHT 100
#define FRAME_BOTTOMY FRAME_TOPY + FRAME_HEIGHT
#define SCR_HEIGHT 320
int idx = 0;
#define IDX_MAX 240
BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
BLECharacteristic* pChar_temp = NULL;
BLECharacteristic* pChar_humi = NULL;
bool deviceConnected = false;
bool oldDeviceConnected = false;
// See the following for generating UUIDs:
// https://www.uuidgenerator.net/
#define SERVICE_UUID "FC8601FC-7829-407B-9C2E-4D3F117DFF2D"
#define CHAR_UUID_TEMP "0FD31907-35AE-4BB0-8AB1-51F98C05B326"
#define CHAR_UUID_HUMI "D01D3AF7-818D-4A90-AECF-0E1EC48AA5F0"
class MyServerCallbacks: public BLEServerCallbacks {
void onConnect(BLEServer* pServer) {
deviceConnected = true;
BLEDevice::startAdvertising();
Serial.println("MyServerCallbacks.onConnect");
};
void onDisconnect(BLEServer* pServer) {
deviceConnected = false;
Serial.println("MyServerCallbacks.onDisconnect");
}
};
/**
initTemp
Setup DHT library
Setup task and timer for repeated measurement
@return bool
true if task and timer are started
false if task or timer couldn't be started
*/
bool initTemp() {
byte resultValue = 0;
// Initialize temperature sensor
dht.setup(dhtPin, DHTesp::DHT11);
Serial.println("DHT initiated");
// Start task to get temperature
xTaskCreatePinnedToCore(
tempTask, /* Function to implement the task */
"tempTask ", /* Name of the task */
4000, /* Stack size in words */
NULL, /* Task input parameter */
5, /* Priority of the task */
&tempTaskHandle, /* Task handle. */
1); /* Core where the task should run */
if (tempTaskHandle == NULL) {
Serial.println("Failed to start task for temperature update");
return false;
} else {
// Start update of environment data every XX seconds
tempTicker.attach(2, triggerGetTemp);
}
return true;
}
/**
triggerGetTemp
Sets flag dhtUpdated to true for handling in loop()
called by Ticker getTempTimer
*/
void triggerGetTemp() {
if (tempTaskHandle != NULL) {
xTaskResumeFromISR(tempTaskHandle);
}
}
/**
Task to reads temperature from DHT11 sensor
@param pvParameters
pointer to task parameters
*/
void tempTask(void *pvParameters) {
Serial.println("tempTask loop started");
while (1) // tempTask loop
{
if (tasksEnabled) {
// Get temperature values
getTemperature();
}
// Got sleep again
vTaskSuspend(NULL);
}
}
/**
getTemperature
Reads temperature from DHT11 sensor
@return bool
true if temperature could be aquired
false if aquisition failed
*/
bool getTemperature() {
// Reading temperature for humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
TempAndHumidity newValues = dht.getTempAndHumidity();
// Check if any reads failed and exit early (to try again).
if (dht.getStatus() != 0) {
Serial.println("DHT11 error status: " + String(dht.getStatusString()));
return false;
}
rqsUpdate = true;
updateValues = newValues;
return true;
}
void setup()
{
Serial.begin(115200);
Serial.println();
Serial.println("DHT ESP32 example with tasks");
//init DHT
initTemp();
// Signal end of setup() to tasks
tasksEnabled = true;
//init BLE
// Create the BLE Device
BLEDevice::init("ESP32-DHT11");
// Create the BLE Server
pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
// Create the BLE Service
BLEService *pService = pServer->createService(SERVICE_UUID);
// Create a BLE Characteristic for temp and humi
pChar_temp = pService->createCharacteristic(
CHAR_UUID_TEMP,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE |
BLECharacteristic::PROPERTY_NOTIFY |
BLECharacteristic::PROPERTY_INDICATE
);
pChar_humi = pService->createCharacteristic(
CHAR_UUID_HUMI,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE |
BLECharacteristic::PROPERTY_NOTIFY |
BLECharacteristic::PROPERTY_INDICATE
);
pChar_temp->addDescriptor(new BLE2902());
pChar_humi->addDescriptor(new BLE2902());
// Start the service
pService->start();
// Start advertising
BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
pAdvertising->addServiceUUID(SERVICE_UUID);
pAdvertising->setScanResponse(false);
pAdvertising->setMinPreferred(0x0); // set value to 0x00 to not advertise this parameter
BLEDevice::startAdvertising();
Serial.println("Waiting a client connection to notify...");
//init ST7789
tft.init(240, 320); // Init ST7789 320x240
tft.setRotation(2);
tft.setFont(&FreeMonoBold12pt7b);
tft.setTextWrap(true);
tft.fillScreen(ST77XX_RED);
delay(300);
tft.fillScreen(ST77XX_GREEN);
delay(300);
tft.fillScreen(ST77XX_BLUE);
delay(300);
tft.setCursor(0, 0);
tft.setTextColor(ST77XX_RED);
tft.print("\n");
tft.print("ESP32 + DHT11 + ST7789\n");
prvUpdateMillis = millis();
}
void loop() {
if (!tasksEnabled) {
// Wait 2 seconds to let system settle down
delay(2000);
// Enable task that will read values from the DHT sensor
tasksEnabled = true;
if (tempTaskHandle != NULL) {
vTaskResume(tempTaskHandle);
}
}
if (rqsUpdate) {
unsigned long curUpdateMillis = millis();
tft.fillRect(0, 53, 240, 75, ST77XX_BLUE );
tft.setCursor(0, 70);
tft.setTextColor(ST77XX_WHITE);
tft.print(" temp.: " + String(updateValues.temperature));
tft.setCursor(0, 95);
tft.setTextColor(ST77XX_WHITE);
tft.print(" humi.: " + String(updateValues.humidity));
tft.setCursor(0, 115);
tft.setTextColor(ST77XX_WHITE);
tft.print(" mills.: " + String(curUpdateMillis - prvUpdateMillis));
prvUpdateMillis = curUpdateMillis;
if (idx == 0) {
tft.fillRect(FRAME_TOPX, FRAME_TOPY,
FRAME_WIDTH, SCR_HEIGHT - FRAME_TOPY,
ST77XX_BLUE);
}
tft.drawLine(
FRAME_TOPX + idx, FRAME_BOTTOMY,
FRAME_TOPX + idx, FRAME_BOTTOMY - (int)updateValues.temperature,
ST77XX_WHITE);
idx++;
if (idx >= IDX_MAX)
idx = 0;
char bufTemp[5];
char bufHumi[5];
//convert floating point value to String
dtostrf(updateValues.temperature, 0, 2, bufTemp);
dtostrf(updateValues.humidity, 0, 2, bufHumi);
pChar_temp->setValue((uint8_t*)bufTemp, 5);
pChar_temp->notify();
pChar_humi->setValue((uint8_t*)bufHumi, 5);
pChar_humi->notify();
//Serial.println(" T:" + String(updateValues.temperature) + " H:" + String(updateValues.humidity));
rqsUpdate = false;
}
// disconnecting
if (!deviceConnected && oldDeviceConnected) {
Serial.println("disconnecting");
delay(500); // give the bluetooth stack the chance to get things ready
pServer->startAdvertising(); // restart advertising
Serial.println("start advertising");
oldDeviceConnected = deviceConnected;
}
// connecting
if (deviceConnected && !oldDeviceConnected) {
Serial.println("connecting");
// do stuff here on connecting
oldDeviceConnected = deviceConnected;
}
yield();
}
ex_pyBLE.py, Python3 code run on Raspberry Pi 4B running 32-bit Raspberry Pi OS (bullseye), to monitor temperature & humidity from ESP32_DHT_ST789_graphic_BLE.ino.
# To install bluepy for Python3:
# $ sudo pip3 install bluepy
from bluepy import btle
from datetime import datetime
class MyDelegate(btle.DefaultDelegate):
def __init__(self, handleTemp, handleHumi):
self.handleTemp = handleTemp
self.handleHumi = handleHumi
btle.DefaultDelegate.__init__(self)
# ... initialise here
def handleNotification(self, cHandle, data):
now = datetime.now()
current_time = now.strftime("%H:%M:%S")
if cHandle == self.handleTemp:
print("temp:", data, "@", current_time)
elif cHandle == self.handleHumi:
print("humi:", data, "@", current_time)
# Initialisation -------
address = "24:0A:C4:E8:0F:9A"
service_uuid = "FC8601FC-7829-407B-9C2E-4D3F117DFF2D"
char_uuid_temp = "0FD31907-35AE-4BB0-8AB1-51F98C05B326"
char_uuid_humi = "D01D3AF7-818D-4A90-AECF-0E1EC48AA5F0"
p = btle.Peripheral(address)
#p.setDelegate(MyDelegate())
# Setup to turn notifications on, e.g.
svc = p.getServiceByUUID(service_uuid)
ch_temp = svc.getCharacteristics(char_uuid_temp)[0]
ch_humi = svc.getCharacteristics(char_uuid_humi)[0]
print("ch_temp handle", ch_temp.getHandle())
print("ch_humi handle", ch_humi.getHandle())
p.setDelegate(MyDelegate(ch_temp.getHandle(), ch_humi.getHandle()))
"""
Remark for setup_data for bluepy noification-
Actually I don't understand how come setup_data = b"\x01\x00",
and ch.valHandle + 1.
Just follow suggestion by searching in internet:
https://stackoverflow.com/questions/32807781/
ble-subscribe-to-notification-using-gatttool-or-bluepy
"""
setup_data = b"\x01\x00"
#ch.write(setup_data)
p.writeCharacteristic(ch_temp.valHandle + 1, setup_data)
p.writeCharacteristic(ch_humi.valHandle + 1, setup_data)
print("=== Main Loop ===")
while True:
if p.waitForNotifications(1.0):
# handleNotification() was called
continue
#print("Waiting...")
# Perhaps do something else here
remark:
BUT, I found that ex_pyBLE.py run on Raspberry Pi is sometimes unstable; with error of:
luepy.btle.BTLEDisconnectError: Failed to connect to peripheral ...
Next:
~ BLE between ESP32/ESP32C3 (arduino-esp32), notify DHT11 reading of temperature & humidity.
