Android Bluetooth Remote Control Car

The thought of building a remote control car by myself since I was a kid, and I DIY many version of toy cars, boats in my childhood, but no one was remote controlled. Thanks for the quick development of android system and guys that like sharing their DIYs on the internet, I finally implement my version of android bluetooth remote control car.
This DIY referred to this site, http://english.cxem.net/mcu/mcu4.php, if you want get the source code, please jump to the site. I just add some analyze here.
My RC car:

 Wiring Diagram,from http://english.cxem.net/mcu/mcu4.php:

STM32 embedded program flow chart:

Android program UML:

Fix my Lenovo Yoga Pro2

I bought a Lenovo Yoga Pro 2 couple months ago. Unfortunately, the volume increase button was not work suddenly. It might impact the laptop's warranty if I open the laptop and check the issue, so I send it back to Lenovo for repairing. I was told the board which contains the volume control buttons was broken,It took me 3 days waiting to get back my laptop. But I found out a new issue very soon, the screen rotation lock button was not working after the repairing. Actually, this is the reason why most of time I like to check these kind of problems by myself, they always make things worse. So, I open it up and found the root cause, the Lenovo guy forgot connect the button battery wires. Here is the photo after I open the laptop up:

DIY Lumia 620 wireless charging

Lumia 620 phone does not contain wireless charging function. After using other phone with wireless changing, I'm going to like this kind of recharging without inserting usb cable to phone. So I decided to add a wireless function to my Lumia620, here we go:
Add wireless charging to Lumia620(You can download original file)