FYI: this is what happens when you accidentally set HLFCYA

Posted on May 17, 2011 at 12:22

Hi Andy,

You should pay attention that this mode is not allowed and is used to reduce power when operating from HSI or HSE onlya nd not using the PLL. You can refer to the reference Manual, page 31, Here below as well.

STOne-32

Posted on May 17, 2011 at 12:22

I accidentally set HLFCYA, flash access control half cycle access enable.

All program accesses after that returned 0, at least when using HSI+PLL as the system clock.

This first showed up as a breakpoint being hit out of order. When I continued running after the breakpoint the processor executed code sequentially until the PC wrapped around to 0.

It took me a while to note that the disassembly window was showing 0 for all opcodes, while looking at flash directly via the memory window showed the correct program code.