AVR external memory and the "writable strings" option

Introduction

This Technical Note applies to IAR Embedded Workbench for AVR.

If there is no non-volatile memory (that is, no PROM) available in the data address space you should probably use the -y (writable strings, constants) compiler option. When using this option, string literals and constants are placed in code space and then copied from CCSTR and CDATA to ECSTR and IDATA respectively.

If the -y option is not used, string literals and constants are placed in the CONST and CSTR segments in the data memory space. e.g.,

-Z(DATA)CSTR,CONST=9000-FFFF

This requires non-volatile memory in the data address space, e.g., external PROM, to work.

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