Frequently Asked Questions

I cannot access the JTAG/SWD interface any longer. I could before. What is the problem?

It is possible that you have downloaded a program that disable the JTAG interface, mess up the PLL settings or that has enabled a low-power mode where the debug interface is disabled.
The solution is to get the processor into ISP mode. Pull the ISP enable pin low (typically P0.14, P2.10 or PIO0_1) while resetting the processor. When the processor is in ISP/bootload mode, it is possible to connect via JTAG/SWD. A new program can then be downloaded.
In ISP mode, it is also possible to erase the flash completely (via for example FlashMagic) to get back to the starting point.

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