I encountered it in driving the OLED and capacitive buttons, so I recorded this error and I would not be at a loss if I encountered it again later.

Keil’s Debug picture

Is the definition repeated? I didn’t see it anyway when I was looking for the file

The problem is solved. The reason is that I did not declare in the header file, but directly defined the variable, and the corresponding C file did not have the definition of the variable, so this error occurred. The
solution is to move the variable in the header file directly to In the c file, and then declare in the header file, for example, in the c file, it is const unsigned char F6x8[][16]declared in the header file extern const unsigned char F6x8[][16], and that’s it!