Reliable Bluetooth LE Comms Between Arduino and MIT App Inventor (AI2)

MIT_AI2_IconIn a previous post, I looked at creating reliable communications using Classic Bluetooth. While that approach works well, and is a reliable way to connect devices, there may be circumstances when a Bluetooth Low Energy (BLE) connection is preferable.

As it turns out, Bluetooth and BLE are about as similar as apples and oranges. The change in transmission protocol technology is more than a trivial change in the code and its structure.

In this article I explore the difference between BT and BLE and how the previous BT AI2 app needs to be adapted.

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Reliable Bluetooth Comms Between Arduino and MIT App Inventor (AI2)

MIT_AI2_IconI recently needed to develop a Bluetooth application between an Arduino and a controlling App running on Android. App Inventor 2 was used to simplify development of the Android App .

MIT App Inventor (AI2) is a web-based online graphical mobile application development environment for Android devices, where you can create an application by simply dragging and connecting a series of function blocks.

When researching the task, I found a lot of disparate information about how to write the Bluetooth management code for AI2. This information (some good, some wrong, and a lot repetitive) was synthesized it into a set of functions, described here, that provide a reliable communications interface to my project.

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Parola A to Z – Text Animation

azparola_animationThe key function of the Parola library is to display text using different animations. These animations are built around a core supporting framework and largely follow the same patterns. This article explores how Parola animations code is constructed so that advanced users of the library have enough information to be able to write (and contribute!) their own new animations.

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Switches as User Input Devices

KeySwitchThe humble switch is one of the major ways that users can interact with Arduino based code. Often the input comes from some variation of the momentary-on push switch, like the tact switch on the left, connected to an input on the microcontroller.

Users of modern GUIs will be familiar with being able to express themselves through a keyboard and a mouse. So user interface elements like double-clicks, long clicks and keyboard auto-repeat are familiar.

However, a lot of microcontroller code simply restricts the use of these switches to on/off functionality. Arduino programmers often don’t understand how to provide more features, even though a single switch can be made to do much more for a user.

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Relay Timer with LED Display

Relay_Timer_Ortho_ViewAs part of a bigger project, I needed to make a timer that would activate a relay for a set time to switch power on/off to another device. Rather than buy one I decided to build my own from electronic bits and pieces that were on hand in my workshop, wrote some software for a ‘spare’ Arduino Pro Mini that was lying around and packaged it all up in a small box. It turned out to be quite functional, so I decided to document the build in case someone else finds this useful.

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