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‘The Ultimate Arduino Kit’ and Bluetooth

To introduce myself to Arduino I picked up a book and ‘The Ultimate Arduino starter kit’ from Oddwires.com. For the first few chapters everything was going as described and then I hit the H-Bridge IC, which the kit did not include.

Motors

I wanted to understand motor controls. This kit has brushed DC motor, a Stepper motor, and a Servo. Instead of expecting you to create a voltage divider and isolation circuits for the motors the kit comes with a L298N Dual H-Bridge DC Stepper Motor Controller.

Here I became familiar with looking at spec sheets because there are many manufacturers of the L298N. Getting past the first issue upon landing on the right reference I jumped in with what should have worked.

My stepper was vibrating and twisting but not as expected. Though not clearly marked or noted anywhere I saw the stepper motor wires are paired, Red/Blue and Black/Green in my case but different manufactures use different colors. I established the colors from the spec sheet wiring diagram found by searching for the part number on the motor.

The sketch code seemed to be readily available for most things with good support libraries so I’ve been able to make most everything work. It does require attention to details and as I will explain next a willingness to just jump in with what you have.

Bluetooth

Instead of being a nicely setup board the kit has two components requiring surface soldering the two board together.

I made a simple jig from a piece of wood, a wire coat hanger, small plastic cap and a felt pad. The two circuit boards were quite slippery when put together and I was having a hard time getting an alignment to hold until I positioned the header pins over the edge of the board. Once it was flat the jig worked well.

This was my first surface mount soldering and I used a cheap butane iron. Once I got the hang of it I was surprised how quickly it went.

With de-soldering braid I was able to clean up the blobs and shorts but I could definitely see how a good iron with the right tip would make the job much easier.

For sketch script I had to search a bit and ran across Genotronex.com which appears to be the manufacturer. I’ve included their sketch.

I found this code on the Genotronex website (translated via Chrome).

NOTE: This HC-05 module accepts up to 5.0V on the signal lines so there is no need for a voltage divider.

The default name of the Bluetooth module is HC-05 and the password is 1234.

Summary

Adding Bluetooth eliminates the need for buttons and menus on the device for settings. Communicating basic commands to the Arduino is all that is necessary. The UI is an Android application that sends commands when connected. This allows the UI to be updated and removes the overhead of buttons and programming on the Arduino device. Setting the clock is one example of an interaction that requires buttons, logic, and a menu that can be eliminated.

Next Steps

Now that I’ve gone through setting up all of the components in the ‘Ultimate’ kit it is time to create the Android interface.

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