Why am I getting a "Cannot stop CPU" error message?
This error message is displayed when the debugger is unable to make the ARM stop running and enter debug mode typically after carrying out a reset. This error message could be caused by the following:
- Unreliable JTAG/SWD Connection — Try reducing the JTAG/SWD clock frequency or reducing the target interface's cable lengths as much as possible.
- Incorrect support package — Make sure you are using a CPU/board support package intended for your part.
- Incorrectly connected reset signals — Typically the nSRST signal should be connected to the target's core reset signal, it should not be connected to the JTAG TAP reset (TRST) signal.
- Invalid code has been executed — This may be caused by your program not being loaded correctly, a problem with the target's memory or a bug in your program. You can check the download and memory by verifying the download.