Using android mobile to control arduino

cyclegadget:
I wonder if you have to test for bytes available? In the Arduino it would be a test like if(Serial.available()){ Serial.read } .

In the code blocks you have a something that says BluetoothClient1BytesAvailableToReceive.............I think it should be combined with a if > 0 { read the byte }....or something like that.

Well yeah, but you can't have (Serial.available()){ Serial.read } all by itself - meaning the control structure block has to be attached to something else - ideally it should happen with no user input. The only thing I can think of is to have it inside Clock.timer block and set it to fire every 10 ms or so. That's not ideal but it might work.

I had had some problems when I tried to implement it. Though the idea might be ok. I might have messed up something else - it is possible I sent data more often than the app received them and that freezed the app because of the buffer. Well at least that's my understanding of it

Where did you get the bluetooth module?

it's a BTM222 module on a custom breakout board - kind of cool because it is a class 1 device - so the max range is not 10m but 100m :smiley:
I bought it from a local tinkerer who makes them - so I don't think you'd be able to get it

Though there are lots of such boards all over ebay - though most of them are class 2 (range ~10meter)

kerimil:
I had had some problems when I tried to implement it. Though the idea might be ok. I might have messed up something else - it is possible I sent data more often than the app received them and that freezed the app because of the buffer. Well at least that's my understanding of it

I kept getting the same thing, its quite frustrating as my phone takes forever to recover! In my arduino code I just had Serial.println(...) in the loop and had my app to receive text every 1 second (with delimiter byte set to 13). I either get some odd values or it just crashes.

it works but only if serial data is received as often as it's sent... so your arduino code should send the data every 1 second

First of all THANKS,
this was the project that I was waiting for.
I do not understand very much the wiring connection, especially the bt connection, my lack.
green wire: pin0 (arduino) - ? (bt)
yellow wire: pin 7 (arduino) - led
black wire: ? (arduino) - resistor - ? (bt)
red wire: ? (arduino) - ? (bt)

and like in a loop I finish with
End of all THANKS

Oh sorry I forgot to post wiring diagrams here. Now it should be a lot easier to understand.


If you can't see the pics just go here -> http://www.instructables.com/id/How-control-arduino-board-using-an-android-phone-a/

I found out how to send data from the app to cosm website

here is a video showing an example app as well as a brief explanation of how to use app inventor

You can download the app here >>
Download at SpeedyShare

Here you can download the source >>
http://speedy.sh/Vwwww/bluetoothAppCosmExampleTemperature.zip

Here is arduino code I used (note that you need OneWire library for it to work)

#include <OneWire.h>
int DS18S20_Pin = 2; //DS18S20 Signal pin on digital 2

//Temperature chip i/o
OneWire ds(DS18S20_Pin); // on digital pin 2



void setup()
{
  // initialize the serial communication:
  Serial.begin(19200);
  // initialize the ledPin as an output:

}

void loop() {


   float temperature = getTemp();
Serial.println(temperature); delay (250);

} 


float getTemp(){
//returns the temperature from one DS18S20 in DEG Celsius

byte data[12];
byte addr[8];

if ( !ds.search(addr)) {
//no more sensors on chain, reset search
ds.reset_search();
return -100;
}

if ( OneWire::crc8( addr, 7) != addr[7]) {
Serial.println("CRC is not valid!");
return -1000;
}

if ( addr[0] != 0x10 && addr[0] != 0x28) {
Serial.print("Device is not recognized");
return -1000;
}

ds.reset();
ds.select(addr);
ds.write(0x44,1); // start conversion, with parasite power on at the end

byte present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad


for (int i = 0; i < 9; i++) { 
data[i] = ds.read();
}

ds.reset_search();

byte MSB = data[1];
byte LSB = data[0];

float tempRead = ((MSB << 8) | LSB); 
float TemperatureSum = tempRead / 16;

return TemperatureSum;}

And here is the feed I created for the app -> The feed is available here - https://cosm.com/feeds/118188

In order to send data from or to your own COSM feed you have to modify the URL as follows (parts that you have to fill in are in capital letters):

http://api.cosm.com/v2/feeds/YOUR FEED ID/datastreams/YOUR DATASTREAM ID.csv?key=YOUR API KEY&_method=put

Then copy and paste the URL into a QR code generator, generate a QR code and scan it using the app. You might as well use the feed I created for the app - it's the default URL set in the app so you don't have to enter it - it's already there

If you have any questions feel free to ask them

When is necessary to use a level-shifter? some people use the 74HC4050N level shifter in conjunction with the btm222 module!

The module I got has a proper level shifter on it, but AFAIK one could improvise with zener diodes to achieve the same effect (not that level shifters are very expensive)

Tanks a lot Kerimil for your project vert helpfull.
I tried to do the same without Voice recognising. The connection From my phone and Bluetooth device is ok, the wiring sure ok ( rx to dx and dx to rx). But nô serial data is send. On your sketch, you initialise serial communication with 19200 bauds. I think the Bluetooth deviçe should send is data at same speed. Where did you initialise serial data speed on Bluetooth device? Perhaps the problème comes From there.
Tanks for your answer

Where did you initialise serial data speed on Bluetooth device?

Between the Bluetooth device and the phone, the serial data speed is solved during "pairing" of the device to the phone. At least this is my belief.

Where did you initialise serial data speed on Bluetooth device?

Cyclegadget is right - it's either when pairing or whenever connection is established

Even if baud rate was wrong you'd still receive something - if you don't then it has to be something else.

Verify if the module and the mobile works using a USB bluetooth dongle and a program like putty. Also check the datasheet of the module and the settings - is the module set as slave or master ? For apps I created it has to be set as master

Thanks for sharing your work. I tried it without voice detection. BT is paired with my phone but apperently no serial data is send. If I try to send "1" or "2" with my computer connected in bt, using putty the led switch on and off correctly so the hardware and arduino sketch is ok. my problem is coming from app inventor. what is button 1 set and number for? is the real value 1 and 2 are send or ascii value. I tried with mega 2560 with external power and connect rx and tx to serial 0

@sisyph

I recommend you share your code that you are using, just to eliminate the possibility of the code being the problem.

ohh I see now... the problem you are experiencing is caused by data types

The app sends bytes so it converts '1' into '49' and that's what's sent through bluetooth.

Ohh and you really should have connected the app to the bluetooth dongle - that would make everything clear for you.

Yeah !! it works.
I used in my sketch : case '1' : instead of case 1:
So many hours for ''...
The strange things is that it worked before when I used my bt connection with my computer...
Thanks for your help

Just found this app. Those who are interested can check out ArduinoCommander android app too:
https://play.google.com/store/apps/details?id=name.antonsmirnov.android.arduinocommander

hi kerimill,

i wanna buy a bluetooth for this project.so just went through ebay and found this link

http://www.ebay.com/itm/JY-MCU-HC-06-V1-03-Bluetooth-Transeiver-RF-Module-Wireless-Serial-4p-Port-line-/261053366958?pt=LH_DefaultDomain_0&hash=item3cc7fe42aehttp://www.ebay.com/itm/JY-MCU-HC-06-V1-03-Bluetooth-Transeiver-RF-Module-Wireless-Serial-4p-Port-line-/261053366958?pt=LH_DefaultDomain_0&hash=item3cc7fe42ae

this bluetooth module has a pairing code 1234. so to pair this module with ur app, should i modify ur project?? will it automatically ask for code??
plz tel me that can i use this module??

thnx
Jazly :slight_smile:

The app doesn't have to pair with the module - just pair with it from the phone and then run the app

It should work just fine - just make sure you check the datasheet of the module & make sure the baud rate is the same (if so then the arduino code has to be modified or the setting of the module)