I recently started working on ARM controllers. I have been using RealView MDK 3.22. However I noticed that, when I was trying to run my simple program involving UART peripheral, it was getting compiled but was not running when downloaded on uC.
The same program started working when I downloaded MDK 3.7. So if your programs are driving you nuts because of some strange reasons, which you are not able to figure out, then update to latest version.
