BL51: Warning 1 (Unresolved External Symbol) Using SBITs
Information in this article applies to:
I want to use a bit of Port P1 for a chip select line. I have declared the chip select as follows:
In a second module I need to access this SFR, so I declare it as an extern:
When I link, I receive the following linker error:
Where have I made a mistake?
Unfortunately, you can't declare sbits as extern. You must declare the sbit in each C file (or create a header file for it). Just include the SBIT definition you already have in each file.
Last Reviewed: Thursday, February 25, 2021
of your data.