Content originally posted in LPCWare by Pacman on Wed Jun 11 22:13:47 MST 2014
First of all, I've never used LPCExpresso, so I might be completely off in parts of this reply!
Make sure you're not using two different USB cables. :)
Why ?
-Once I had a problem with two identical boards. One would work, another wouldn't.
I used two different USB cables, and since USB cables are usually manufactured by low-cost wires (the lowest possible), the resistance in the cables might be too high for the voltage to reach the target.
I've measured some (bad) cables to be more than 2 Ohms on 0.6 meter (2 ft), and some (good) cables to be less than 0.5 Ohm on 1.8 meter (6 ft).
So try plugging it into the same cable.
If you're already using the same cable, and the results differ, the problem could be in your firmware.
If a variable is not initialized correctly, it will most likely cause periodic errors.
I'm believing, that in this case it's a firmware bug. I believe an interrupt crashes the chip, preventing it from running.
If the LED starts blinking and stops after a while, it indicates that the firmware was running, but crashed. Yes, the crash can be because of lack of power (monitor your voltage supply and your current usage).
Have you tried running the program without using the debugger ?
Other than the above mentioned, nothing comes to mind what could be wrong; but it's worth checking out. Make sure you check the voltage that the chip receives.