In this project I’m going to show an Android app that sends a message to your Arduino via bluetooth. And that message will be displayed in a Doted Matrix display.
Resources for this project:
- How To Use App Inventor With an Arduino
- Control 2 DC Motors Via Bluetooth with an android app created with MIT App Inventor
- Review of the Freetronics DMD 32×16 Red
- Review of the HC-05 Bluetooth Module
Watch the video below
Parts Required
- 1x Arduino Uno
- 1x DMD (Click here to buy one or read my review here)
- 1x Bluetooth Module (for example: HC-05, click here to read my review here about this Bluetooth module)
- 1x Smartphone (any Android will work, I’ve only tested with Samsung Galaxy Ace)
- Android Application (you can download it in the next step)
- 1x Breadboard
- Jumper Cables
 
Schematics
![[Schematics-compressed]](https://i0.wp.com/randomnerdtutorials.com/wp-content/uploads/2014/02/Schematics-compressed.jpg?quality=100&strip=all&ssl=1)
Source Code
- Arduino Sketch
- Install the DMD library
- Send_Message.apk
- Send_Message.aia (to edit the android app)
Note:Â If you want to edit my app this is what you need to do. Download Send_Message.aia and upload it to MIT App Inventor.Â
Tips:
- You need to remove the RX and TX cables when you’re uploading the sketch to your Arduino.
- Sometimes people connect the TX from the bluetooth module to the TX of the Arduino… that’s wrong and it won’t work. Make sure you connect it properly, the TX into RX and the RX into the TX.
- If the HC-05 Bluetooth Module asks for a password, It’s ’1234′.
- Before Testing my android app, test if you’ve made all the connections correctly. How you can do that? Simply enter some messages (for example: “Random”) into your serial monitor and your DMD should display that message.
I hope you found this useful!
Do you have any questions? Leave a comment down below!
Thanks for reading. If you like this post probably you might like my next ones, so please support me by subscribing my blog and my Facebook Page.
P.S. Click here to see how to use MIT App Inventor with Arduino
it took a series of adapter..
Hi ian,
What exactly you mean by that?
whether it can function in Anroid 4.2?
If I use the bluetooth hc-06 does not work? whether to use hc-05?
just wanted to say your program works great.
I would like to add a checkbox to be able to have an option to turn a buzzer on for 2 seconds when a text is sent, any ideas how I can accomplish this I am new to Mit and arduino. thank you for any help
Hi Brit,
MIT App Inventor comes already with a checkbox function.
Under the menu called: “User Interface” search for “checkbox” and drag and drop into your app screen.
Then go to the Blocks section and create an if condition.
If that checkbox is ticked it also sends something else that the arduino will recognize and trigger the buzzer.
I hope this helps,
Rui
Hello Rui,
Another Great upload!!!!!!
But finding difficulty to download send_message.apk app,because the link provided by you is directing me to send_message.aia.
So please give an appropriate link to download send_message.apk
I shall be thankful to you.
Hi Shantanu.
I’ve just tried to download the .aia file myself and it worked fine…
Please try again
https://randomnerdtutorials.com/wp-content/uploads/2014/02/Send_Message_aia.zip
Thanks!
How can I modify to enter a message of 1000 characters?
Yes Kerry,
Feel free to add as much characters as you want.
Just change the arduino code, instead of saving 100 characters change the size of the array to 1000 🙂
HI,
Can we use a long range bluetooth module like NRF24L01, so that we can send texts from a long distance.The link is provided below:
ww.digibay.in/wireless/nrf24l01l-long-range-module-1km-arduino-compatible
Hi Shantanu,
I think so. any bluetooth module that works with a simple serial communication at 9600 baud rate. Should work just fine with this project!
When I use more than 2 displays some of the characters from the phone are dropped. Any suggestions of why. Using 4 displays. Only 2 displays work…
You might need to change some of the arduino code that is printing the string received from the android app.
But before you change my arduino code. You should create a Serial.println() to see what your arduino is receiving from the smartphone and see if everything is working properly..
Hi Rui!
Now i want to work on the sounds, i mean a buzzer for every new message.
Can you please EMail me the schematic in Fritz format? Will help me a lot.
-Sagar
Hi Sagar,
Unfortunately I don’t have the fritizing schematics for this project anymore… at least I can find them on my computer.
Have a nice day,
Rui
DMD working fine, bluetooth is also working fine, app is also getting connected to the bluetooth. We also followed your specified guidelines, but still we are facing problems in the form of the DMD not displaying the specified message from that app.
Your assistance will be highly appreciated.
Awaiting your reply.
Thank you.
Are you using the same DMD as me?
The DMD doesn’t display any message at all?
is your bleutooth module working properly?
By default most bluetooth modules are set a 9600 baud rate such as the arduino to establish a serial communication.
If you bluetooth module is set at a different baud rate it won’t work properly and it won’t receive the message
I have the same problem, and yet get the solution. lease help
greatt..
tool works well
I was wrong to install cable
Awesome, I’m glad it is working now!
Is it mandatory to use Arduino UNO?????
Doesn’t it work with Arduino Duemilanove???
Because we are using the latter i.e Duemilanove, and the Message is not being displayed in the DMD.
Please Help!!!!
Hi…
Arduino Error…”DMD does not name a type” ?????
Hi Arif,
Make sure you install the DMD library properly in your Arduino IDE.
Descarque el archivo pero App Inventor no me permite importar el archivo me dice que no es compatible. A que se debe?. Gracias
Hi Rui,
I would like to know since I am intending to use this same idea to create an android app on a different platform which will be android studio. Plus I would like to add the features like templates and make the displayed messages to be static and i need to increase the range of the Bluetooth. Will i still be able to use your codes with some editing or the codes wont work since the development platform is totally different.
Hi Jesjeet,
As you said the platform I’m using (MIT App Inventor) is totally different,
so you can’t use my applications with Android studio.
I might do some projects with Android Studio in the future, but right now I have plenty of other projects to finish.
Thanks,
Rui
If I use the example https://www.youtube.com/watch?v=-CrMqVppsdc do in Bluetooth phone messages, what to do, you can give me the program on behalf of the source code download? Or send me mail zx08094490 @ yahoo .com.tw. thanks
Thanks, it’s works.
Thank you!
Thanks for a great tutorial. I do have a question, the LED board is a little expensive do you think or can you do a tutorial using 8 of these,
they are MAX7219 Dot matrix module MCU control Display module ?
Thanks,
Right now I don’t have time to create that project, but it is possible to replace the matrix with those LEDs
Hello, both of the links for the Android phone app are the save, they both are .aia files. The one which says “Send_Message.apk” , after I unzip it is also “Send_Message.aia”
Can you post the “Send_Message.apk” so I can run it on my phone?
Thanks,
You are right, I had the wrong link. I’ve updated the blog post with the proper link for the .apk file.
Thanks!
Hi Rui!
Very interesting, i like it honestly and i have an idea that it can be an addition to this project : is when the client for example is away from his panel that contain the DMDs(more than 1 for ex.) and he would send a msg(SMS) from the smartphone to the panel, is it possible?
Hi Rui… Can you tell me proper interfacing of dotted Matrix such that it can display moving alphabets… Please e-mail me…..Help me out….
I only have the tutorial for that specific dot matrix.
Thanks,
Rui
CAN I GET CODE FOR ESP8266 Controlled dmd display
I don’t have any tutorial on that exact subject. Thanks for the suggestion,
Rui
This blog has become my reference
I’m glad I could help,
Rui