Send data measured by DHT22 sensor connected to ESP32 via Bluetooth
For more details you can read this tutorial :
https://www.robotique.site/tutorial/s...
To send temperature and humidity data measured by a DHT22 sensor to a smartphone via Bluetooth, you can follow these general steps using an ESP32 microcontroller:
Hardware Setup:
Connect the DHT22 sensor to the ESP32. Typically, it involves connecting three wires: one for 3.3V, one for GND, and one for data (signal).
Software Setup:
Install the necessary libraries for the DHT sensor and Bluetooth communication in the Micropython:
For the DHT sensor, you can use the "DHT ".
For Bluetooth communication, the ESP32 has a built-in BluetoothSerial library.
Smartphone Setup:
Use the available blocks in App Inventor to:
establish a Bluetooth connection with the ESP32
receive the data sent by the ESP32 via Bluetooth
display it in your app.
Data Reception on Smartphone:
Pair your smartphone with the ESP32 using the Bluetooth settings. Once connected, the smartphone will receive the temperature and humidity data from the ESP32 over Bluetooth.
You can view and monitor the data in real-time through the terminal application on your smartphone.
The components required to use DHT22 sensor by ESP32 board
ESP32 board:
DHT22 Temperature and Humidity Sensor
Jumper Wires:
Breadboard:
Mounting the ESP32 board with the DHT22 sensor
This represents the basic connections between the DHT22 sensor and the ESP32 board:
Connect the VCC(+) pin of the DHT22 sensor to the 3.3V pin on the ESP32 board.
Connect the OUT pin of the DHT22 sensor to a digital pin GPIO 23 on the ESP32 board.
Connect the GND(-) pin of the DHT22 sensor to any ground (GND) pin on the ESP32 board.
Programming the ESP32 with MicroPython:
1- Flash your ESP32 with MicroPython using this file esp32-20210902-v1.17.bin.
2- import this two libraries : ble_uart_peripheral.py and ble_advertising.py
3- Writing MicroPython code for the DHT22 sensor:
Here's an example of MicroPython code to read data from the DHT22 sensor and send it via Bluetooth:
########## DIGITAL MANUFACTURING ##########
PIKACHU Project
Authors: Miguel Angel Guzman
Kadriye Nur Bakirci
###########################################
########## IMPORT REQUIRED LIBRARIES ##########
import bluetooth
from ble_uart_peripheral import BLEUART
from machine import Pin
import dht
import time
DHT22 sensor configuration
p23=Pin(23, Pin.IN)
d=dht.DHT22(p23)
Create BLE object
ble = bluetooth.BLE()
Open UART session for BLE
uart = BLEUART(ble)
Define ISR for an UART input on BLE connection
def on_rx():
Read UART string, AppInventor sends raw bytes
uart_in = uart.read() # read the message received from the Smartphone via Bluetooth
print("UART IN: ", uart_in.decode()) # display the message received from the Smartphone on the Thonny console
Map ISR to UART read interrupt
def env_tx(val_tx):
uart.write(str(val_tx) + '\n')
print("tx", val_tx)
Map ISR to UART read interrupt
uart.irq(handler=on_rx)
while True:
message="";
d.measure() # Read data from the DHT22 sensor
t=d.temperature() # read temperature
h=d.humidity() # read l'humidity
print('Temperature=', t, 'C')
print('Humidity=', h)
message=str(t)+" °C"
env_tx(message) # send temperature to Smartphone
message=str(h)+" %"
env_tx(message) # send humdity to Smartphone
time.sleep_ms(2000)
uart.close()
Develop a mobile application with App Inventor
1- Create the designer of mobile app with App Inventor.
Use the available Bluetooth components to establish a connection with the ESP32.
Add labels or text fields to display the received sensor data.
Here is the Designer part of the application with App Inventor :
2. Programming the application with App Inventor:
a- Use the available blocks in App Inventor to establish a Bluetooth connection with the ESP32.
Starting with Android 12, Bluetooth permissions have been enhanced to improve security and user data protection. This is why we must declare the authorizations that your application needs in the AndroidManifest.xml file. For Bluetooth, you'll need to include ACCESS_FINE_LOCATION, BLUETOOTH_SCAN, and possibly BLUETOOTH_CONNECT permissions, depending on the features you're using.
Use these programming blocks to connect the smartphone to the ESP32 board via Bluetooth:
b- Receive the data sent by the ESP32 via Bluetooth and display it in your app.
Testing and Debugging:
1- Upload the MicroPython code to your ESP32.
2- Install and launch the app created with App Inventor on your smartphone.
3- Connect to the ESP32 from the app.
4- Verify that the temperature and humidity data from the DHT22 sensor are received and displayed correctly in the app.