HC-05 Bluetooth link with zero code

So you want to two HC-05 modules to automatically connect together, as soon as they're powered up and with zero code? Well this is your lucky day since this can be done using the AT+BIND command.

Let's do this thing!

For this, you will need:

• 1 Arduino (I'm using UNO)
• 2 HC-05 modules
• 1 breadboard
• Wires
• Arduino IDE (I'm using version 1.0.5-r2)

Step 1 - Code and Wires

To bind the two HC-05s, we will need to input AT commands manually which can be done using this simple code made by techbitar.

1.1 Upload the code to your Arduino.
1.2 Using one of your 2 HC-05, follow very carefully the wiring instructions (this is where most people make mistakes.)
  Note that the pins layout on your HC-05 might be different so read the pin label and be sure to connect the right ones.

Step 2 – Configure the Slave

2.1 Make sure the power wire(5.0v or 3.0v) is disconnected from the HC-05
2.2 Make sure the Key wire is connected to pin 9
2.3 In the Arduino IDE, goto the Tools\Serial Monitor menu
2.4 The two following settings are correctly set (at the bottom right of the window):
2.4.1 Line ending should be set to “Both NL & CR”
2.4.2 Baud speed should be set to “9600 baud”
    Note: f you had to modify those settings, I suggest to close and re-open the Serial Monitor dialog
2.5 When the Arduino is reseted (opening the Serial Monitor dialog will force a reset) you should see the following text “Enter AT commands:” in the Serial Monitor dialog.
2.7 Connect the power wire(5.0v or 3.0v) on the HC-05.  You should see the red light slowly blinking (once every ~2 seconds)
2.8 In the Serial Monitor, type AT and press Enter (or click the Send button).  The module should return OK right away
2.9  In the Serial Monitor, type AT+ROLE=0 and press Enter.  This will set the module in Slave mode. You can verify that it worked by typing AT+ROLE? (It should return +ROLE:0)
2.10 In the Serial Monitor, type AT+BIND= and press Enter.  This will remove any existing binding. You can verify that it worked by typing AT+BIND? (It should return +BIND:0:0:0)
2.11 In the Serial Monitor, type AT+ADDR? and press Enter.  This will return the MAC address of this HC-05 module. For example: my module's address is 00:13:03:19:14:07 and the command is returning +ADDR:13:3:191407. As you can see the zeros are stripped out and the formating is a bit different but, as you will soon see, this will not be a problem.  Write down on a piece of paper this MAC address.
2.12 Disconnect the power wire from the HC-05 and remove this HC-05 from the breadboard.  It is now ready to act as the Slave module.
   Note: Don't disturb the wiring since you will use it to configure the second module.

Step 3 – Configure the Master

*Start by installing the second HC-05 on the breadboard. Exactly where the first module was plugged.

3.1 Make sure the power wire(5.0v or 3.0v) is disconnected from the HC-05
3.2 Make sure the Key wire is connected to pin 9
3.3 In the Arduino IDE, goto the Tools\Serial Monitor menu
3.4 The two following settings are correctly set (at the bottom right of the window):
3.4.1 Line ending should be set to “Both NL & CR”
3.4.2 Baud speed should be set to “9600 baud”
    Note: f you had to modify those settings, I suggest to close and re-open the Serial Monitor dialog
3.5 When the Arduino is reseted (opening the Serial Monitor dialog will force a reset) you should see the following text “Enter AT commands:” in the Serial Monitor dialog.
3.7 Connect the power wire(5.0v or 3.0v) on the HC-05.  You should see the red light slowly blinking (once every ~2 seconds)
3.8 In the Serial Monitor, type AT and press Enter (or click the Send button).  The module should return OK right away.
3.9  In the Serial Monitor, type AT+ROLE=1 and press Enter.  This will set the module in Master mode. You can verify that it worked by typing AT+ROLE? (It should return +ROLE:1)
3.10 In the Serial Monitor, type AT+BIND=13,3,191407 and press Enter (of course here you should be using your MAC address that you have noted on step 2.12).  This will force the Master module to automatically link (bind) to the Slave. You can verify that it worked by typing AT+BIND? (It should return +BIND:13:3:191407)
3.11 Disconnect the power wire from the HC-05 and remove this HC-05 from the breadboard.  It is now ready to act as the Master module.

Done.

Now if you power both modules, they will connect right away. It doesn't matter if you power one before the other one.  They will always initiate the connection automatically.  All you need to use them in your next Arduino project is to open a Serial port and communicate through it.

Edit 1: Get more info on HC-05 through this previous post and this video.

This post is featured on:

• Dangerous Prototypes
• Electronics Lab
• Planet Arduino
• PIC Microcontroller

A Maker in the Quebec Fortress

A couple of weeks ago I saw a tweet from @hackaday about their new hacker contest.  The prize is only a trip to space... an actual trip to space worth around 200k.  That evening I was browsing the contest page to get more details and then I reached the eligibility section where it stipulates that the following can't participate: [...]Quebec, Italy, Cuba, Iran, Myanmar (formerly Burma), North Korea, Sudan, Syria, or any jurisdiction where the Contest would be restricted or prohibited by law [...]

The thing is, I was not too surprised since this happens often in Quebec where we have some retarded laws to control the lotteries.  Quebec is surely not the only place in the world where lottery & gambling is controlled but I think we're the only ones that are dumb enough to think that we can control all the world-wide lotteries. The result is that Loto Quebec, the government body controlling this, is trying to impose those crazy conditions on out-of-Quebec contests. So any contest with a prize must submit to those conditions and guess what, for only a small pool of 6 million people, they don't.  You ear that, contest organizers from around the world? Keep your free money and space trips. We have maple syrup.

...

So I can't register my project on Hackaday. Life goes on.

I recently acquired an Ultimaker 3D Printer and that was a huge moment for me.  I have so many projects that can benefit from this that I don't know where to start.  After a few days of learning the limits of the printer I was ready to start working on a project, and to make it even better why not a contest. So I returned to an old ongoing Intel contest page: the Make it Wearable Video Contest.  This place is a really cool mix of art, technology and people that I want to connect with.  Well you know the twist of that story.  This project [...] is open only to legal residents of Argentina, Canada (excluding the Province of Quebec), [...].

GnhaaaaaAAAAAAAaaa.

So I was ranting to people at work about the stupidity of this law but, deep inside, I thought that it wasn't too bad for now and that I could still connect with the Maker community through blogs, videos, twitter and so on.  “I'm a good sheep, I am.” (in the voice of My Fair Lady)

Then, a couple of days ago, the proverbial sh*t hit the fan.

My 9yo son who plays with LEGO Mindstorms found out about the MoonBots contest, a Google Lunar XPrize LEGO Mindstorms Challenge.  This an awesome international on-line competition for kids (9 to 17) where you have to simulate a moon mission.  Needless to say that we were bouncing ideas around and, as the vision of the project took shape, a shiver ran up my back.  I went to my computer and checked the small prints...  guess who can't compete? [...] Cuba, Iran, North Korea, Myanmar/Burma, Zimbabwe, Sudan, Syria, Argentina, Quebec, any other U.S. sanctioned country [...]

$^%&#@#$#&^ You're messing with my kids now.  The gloves are off and Nova Scotia looks like a great place to live.  Maybe I'll shop around for houses.

Where is the best place on earth for a family of Geeks and Maker?

Stealth Evolution

I thought I was following the evolution of the stealth technologies but I had to tweak my understanding based on recent events.

LEGO Test machine #2 is dead after 1 test

Well, that didn't last long.

The machine did 1 full test and then died at about 1/3 of the second test.  The first test result is 32,066 iterations, supporting the result from the Test Machine #1 which ended with 37,112 iterations. So the average is at 34,589 for the moment.

So, why is the machine #2 dead? It didn't died as much as it was slaying DC motors and it all came down to a bad design. One of my goal was to build the machine with only (as much as possible) the Makeblock parts that TLBRC* sent me.  It turns out that I found my nemesis in the motors that where included in the two kits. DC motors.

For something like this build, every molecules in my body was screaming stepper-motors or, at least, servos.  But NoooooOOOoooo, it had to be DC motors, so I looked around for ideas to use them in the same way I would use stepper-motors.   The result was to build physical barriers to stop the motor in known positions.  I knew this would not be good on the motor's gears so I monitored the current going into the DC motors and “tried” to stop them before they were straining. At this point in the story, all the engineers are rolling on the floor laughing. Well, 3 dead motors later, I've learned my lesson: Engineers are cruel and, most importantly, DC motors and made to run freely like wild mustangs in prairies.

The following video was made after the machine killed its first motor.  At that point I thought I could fix it:

Here is my sad video when I decided to stop the machine for good:

What now?  Thanks to Galaxy Quest, my motto is “Never give up, never surrender” and so I have 2 plans:

1. Build a simple machine using stepper-motors.
2. Find a DC motor friendly design and try that too.

But, in order to keep my sanity, I will take a short break from this and work on other projects.


R.I.P. LEGO Test Machine #2.  At least you did 1 full test.




*Again a big thanks to The Little British Robot Company for the 2 Makeblock kits that were used for building this project.  I will reuse those parts on a project pretty soon

Edit:
This story was covered on:

• Ars Technica

HC-05 Bluetooth link of 2 Arduino

In my first Arduino bluetooth experiment, I made an automatic connection between 2 Arduino using BlueSmirf modules. Based on the popularity of that post, it seems that many people are trying to do the same.

On the down side, many of the visitors are looking for a solution using the HC-05 (or other HC-XX type) modules with an AT command interface. I planned to eventually use this type of device but never got around to doing it for every bad reason imaginable including procrastination. This delay was clearly unacceptable for Lyman (one of my readers) who decided to send me 2 extra modules he could spare.

On a side note, this kind soul only has 2 followers on Twitter. Please help me fix this grievous situation.

After playing a bit with my new toy, here's what I've got:

In this first simple example, the code sets the module to be either Master or Slave, connects to one hard-coded address and starts the communication loop. While connected, the Master sends 1s and 0s to the slave who is using this 'command' to switch an LED on or off.

You can get the code on this Git repo.

Breadboard diagram (without the reset connection)

The biggest problem was to figure out how to reset the module programmatically. The [not so good] documentation explains how this can be done by cycling the power but the bluetooth chip has a reset pin that is supposed to do the same trick. I have the code to use the reset pin which I got from this blog post and I will test it soon.

On the HC-05 modules I received, the reset pin is not connected which 'forced' me into making a little hack that can barely be noticed...

The next step will be to recreate the same query and auto-connect loop that I did with the BlueSmirf. It should be straight forward since I've already tested all the necessary AT commands successfully.

Edit 1: Get some tips about using HC-05 in this video I made
Edit 2: I have a new post describing the automatic bind of 2 HC-05 module without having to write code.