App Inventor + Arduino + Bluetooth + DHT22

[João Hebling]

Hi, it's my first aplication with App Inventor. I have some issues with my app, I was developing an app for read humidity and temperature with DHT22 integrated an Arduino and I want to show the data in the app. 

My problem is when I connect to the Bluetooth, the app brake and don't receive the data from Arduino or in some cases receives in half. 

If someone can help, I would be grateful! Sorry my bad english, I prefer don´t use Google Translate because of ba\d translations.

[João Hebling]

[João Hebling]

[Abraham Getzler]

In your Dados screen, you are using a while loop to check for BlueTooth input.

That is a mistake.

The proper way to do that is to use the Clock, set to repeating

faster than the data is being received.

Set the Clock to repeat, and move the inside of that while loop into a new Clock1.Timer event.

ABG

[Abraham Getzler]

Also check the blueTooth and Arduino section of FAq

https://groups.google.com/forum/#!msg/mitappinventortest/wqJin0qO8M0/8xUafdROAgAJ

for samples.

ABG

[Abraham Getzler]

I forgot to add the standard warning about BlueTooth and Screens:

Switching Screens breaks the BlueTooth connection.

ABG

[Juan Antonio]

Try other baud rate 

Serial.begin(9600);

 delay(10000); it is a long time, try delay(100);

To humidity in AppInventor you send U but in Arduino code is H

Here easy codes: http://kio4.com/appinventor/9B_bluetooth_arduino_basico.htm

[João Hebling]

Thank you! It's working right! Now just change some visual things...

[João Hebling]

Thank you! Only realized now that I put the code with some errors, at that time was trying to change the code to try to make the app work and I upload with some errors. The delay time I was because I was trying to fix the errors

[João Hebling]

[Juan Antonio]

This is other example without Clock:

- When Click Button "Obtain Temperature", sends text "T" and gets temperature in Label2.

- When Click Button "Obtain Humidity", sends text "H" and gets humidity in Label3.

// Juan Antonio Villalpando
// kio4.com

#include <Wire.h> 
#include <LiquidCrystal_I2C.h> 
 LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
// LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);

#include "DHT.h" 
#define DHTPIN 2 
#define DHTTYPE DHT11 
DHT dht(DHTPIN, DHTTYPE);
char caracter;

void setup() {
lcd.begin(16,2);// Columnas y filas de LCD 
Serial.begin(9600);
dht.begin();
}

void loop(){
float humedad = dht.readHumidity();
float temperatura = dht.readTemperature();
lcd.clear(); // Borra pantalla
lcd.setCursor(0,0); // Inicio del cursor
lcd.print("Temper. = ");
lcd.print(temperatura);
lcd.setCursor(0,1); // Siguiente renglón.
lcd.print("Humedad = ");
lcd.print(humedad);
delay(300); 

// Bluetooth
if(Serial.available()) {
  caracter = Serial.read();

    if(caracter == 'T')
    { 
        int temper = (int) (temperatura);
        Serial.print(temper);
        Serial.print("\n"); // Fin de línea. Importante.
      
    }
    if(caracter == 'H')
    { 
        int humed = (int) (humedad);
        Serial.print(humed);
        Serial.print("\n"); // Fin de línea. Importante.
    }
        caracter == ' ';
    }
}

- Regards,

Juan Antonio Villalpando.

http://kio4.com/appinventor/9B1_bluetooth_temp_humed.htm

[Ghica]

That is a clever solution without a clock!
Something for the FAQ?

Cheers, Ghica

[Abraham Getzler]

That is a clever solution without a clock!
Something for the FAQ?

Definitely!

 

(added to BlueTooth < 4 and Arduino section of FAQ)

https://groups.google.com/forum/#!msg/mitappinventortest/wqJin0qO8M0/8xUafdROAgAJ

and inserted the critical Designer BlueTooth component Delimiter setting.

ABG