Before I use digitalWrite() on pin13,it works well. Now,the program runs well. But,I can't upload program any more.
the error info: avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x52
value for resp changed every time.
I looked through the web, find nothing about this.
The only different for pin 13 is : a led connected to it on-board. Is that the reason?
My GOD,have to waste time again.