SCM model selection error The STC model in the upper left corner of the STC software
Can't display LCD1602 display plugged in reverse
extern uchar time; uchar time should be added when the error is not defined and used in other files; it cannot be used directly. The
following figure is an error case: it
is okay to define a variable in a .c file and then use extern to quote
it in .h but .h Files cannot use extern to refer to variables
in their own .c files. Variables are generally not defined in .h.
H generally uses macro definition #define, and Baidu knows the macro definition.