B4A is great tool. I do engine management work with AVR mega128 uC, and use BT and Android phone and tablets for the user settings, real time displays and data logging. I am very pleased with performance, much better than notebook and USB dongle for in car work. I took a VB6 app that I developed over a couple years of time, I got an Android version with the major basics working in about 2 weeks. My avatar shows part of my gui for an electronic advance ignition. If you go to my user page, more can be viewed.