This discussion has been locked.

You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Unresolved external symbol warning

I am trying to write a program for cypress FX2 chip. But I am getting the following warnings:

*** WARNING L1: UNRESOLVED EXTERNAL SYMBOL SYMBOL: USBIE MODULE: ex1.obj (EX1)
*** WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL SYMBOL: USBIE MODULE: ex1.obj (EX1) ADDRESS: 0807H

I have declared the header files containing the USBIE.
USBIE is defined in the header file as

EXTERN xdata volatile BYTE USBIE             _AT_ 0xE65C;  // USB Int Enables

What am I missing. The example files I have seen do not have any other include files.

0 Jon Ward over 15 years ago

Take a look at:

http://www.keil.com/support/man/docs/c51/c51_le_absvarloc.htm

Jon
Cancel
Vote up 0 Vote down

Cancel
0 hitheshwer n over 15 years ago in reply to Jon Ward

Jon, I don't understand what's wrong. The declaration seems to be fine.
Cancel
Vote up 0 Vote down

Cancel
0 Mike Kleshov over 15 years ago in reply to hitheshwer n

I don't understand what's wrong

Have you actually read the linked article?
Pay close attention to the paragraph about external declarations.
Cancel
Vote up 0 Vote down

Cancel
0 Thomas Zepf over 15 years ago in reply to hitheshwer n

have you noticed the difference EXTERN vs extern
This is the way how cypress does the things to avoid multiple declarations.

see also
http://www.keil.com/forum/docs/thread8030.asp

Thomas
Cancel
Vote up 0 Vote down

Cancel
0 Andy Neil over 15 years ago in reply to Thomas Zepf

Actually, it's to avoid multiple definitions

c-faq.com/.../decldef.html
Cancel
Vote up 0 Vote down

Cancel