SLAZ290AC October   2012  – May 2021 MSP430F5438A , MSP430F5438A-EP

 

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6.12 CPU30

CPU Module

Category

Compiler-Fixed

Function

ADDA, SUBA, CMPA [immediate],PC behave as if immediate value were offset by -2

Description

The extended address instructions ADDA, SUBA, CMPA in immediate addressing mode are represented by 4-bytes of opcode (see the MSP430F5xx Family User's Guide MSP430F5xx Family User's Guide for more details). In cases where the program counter (PC) is used as the destination register only 2 bytes of the current instruction's 4-byte opcode are accounted for in the PC value. The resulting operation executes as if the immediate value were offset by a value of -2.

Ideal: ADDA #Immediate-4, PC

...is equivalent to...

Actual: ADDA #Immediate-2, PC

** NOTE: The MOV instruction is not affected **

Workaround

1) Modify immediate value in software to account for the offset of 2.  

OR

2) Use extended 20-bit instructions (addx.a, subx.a, cmpx.a).

Refer to the table below for compiler-specific fix implementation information.

IDE/Compiler Version Number Notes
IAR Embedded Workbench IAR EW430 v5.30 or later IDE-based usage enables the workaround automatically. When using the command line, user is required to add the option below: Linker: -D?CPU30_OFFSET=2
TI MSP430 Compiler Tools (Code Composer Studio) v4.0 or later
MSP430 GNU Compiler (MSP430-GCC) Not affected