C51: Assigning an I/O Address to a Variable

QUESTION

How do I assign a variable to a specific memory location, like an I/O address, using µVision?

ANSWER

You may use one of the following methods to assign a specific address to a variable.

1. Use the _at_ keyword when you declare the variable.
2. Use the Absolute Access Macros defined in ABSACC.H in \C51\INC.
3. Use the CODE, XDATA, BIT, and other directives in the BL51 linker to locate a SEGMENT at a particular address.

All three of these methods are discussed in detail in the C51 Compiler User's Guide.

MORE INFORMATION

• Refer to The _at_ Keyword in the Cx51 User's Guide.
• Refer to Absolute Memory Locations in the Cx51 User's Guide.

Last Reviewed: Thursday, February 25, 2021