Simplest of SL4A microbridge examples

We’re familiar with the daunting task of sifting through mountains of code in hopes you can learn how something works. So when a simple example like this SL4A LED toggle comes along we’re thankful for the trimmed fat. If you’re looking to use an Android device to control your Arduino hardware this will be huge shove in the right direction.

The microbridge is used to get the Arduino talking with the Android phone. It involves a USB host shield that lets you connect the two devices via a USB cable. With the USB debugging enabled on the phone, you can use Scripting Layer for Android as a user interface. In this case, a set of Python scripts builds the button and readout seen on the screen above. They also handle sending and receiving commands based on user input. This means you don’t really need to know anything about Android development. We think it would be a great way to get your project through the development stages, and you could learn to write a traditional App later on.

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Adding speech control to an old robotic arm

[Joris Laurenssen] has been hanging onto this robotic arm for about twenty years. His most recent project uses some familiar tools to add voice control for each of the arm’s joints.

The arm has its own controller which connects via a DB-25 port. [Joris'] first task was to figure out what type of commands are being sent through the connection. He did some testing to establish the levels of the signals, then hooked up his Arduino and had it read out the values coming through the standard parallel connection. This let him quickly establish the simple ASCII character syntax used to command movement from the device. There’s only eight command sets, and it didn’t take much work to whip up a sketch that can now drive the device.

The second portion of the project is to use voice commands to push these parallel signals to the arm. Instead of reinventing the wheel he decided to use the speech recognition feature of his Android phone. He used Scripting Layer for Android (SL4A) and a Python script to interpret commands, push them to his computer via Telnet, and finally drive the arm. We’ve embedded the video demo after the break. He gives the commands in Dutch but he overlaid comments in English so you can tell what’s going on.

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