SLAZ290AC October   2012  – May 2021 MSP430F5438A , MSP430F5438A-EP

 

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6.11 CPU29

CPU Module

Category

Compiler-Fixed

Function

Using a certain instruction sequence to enter low power mode(s) affects the instruction width of the first instruction in an NMI ISR

Description

If there is a pending NMI request when the CPU enters a low power mode (LPMx) using an instruction of Indexed source addressing mode, and that instruction is followed by a 20-bit wide instruction of Register source and destination addressing modes, the first instruction of the ISR is executed as a 20-bit wide instruction.

Example:
main:
         ...
         MOV.W  [indexed],SR          ; Enter LPMx
         MOVX.A [register],[register] ; 20-bit wide instruction
         ...

ISR_start:
         MOV.B  [indexed],[register]  ; ERROR - Executed as a 20-bit instruction!



Note: [] indicates addressing mode

Workaround

1. Insert a NOP or a __no_operation() intrinsic function following the instruction that enters the LPMx using indexed addressing mode

OR

2. Use a NOP or a __no_operation() intrinsic function as first instruction in the ISR

OR

3. Do not use the indexed mode to enter LPMx


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

IDE/Compiler Version Number Notes
IAR Embedded Workbench IAR EW430 v6.20 until v6.40 User is required to add the compiler or assembler flag option below. --hw_workaround=nop_after_lpm
IAR Embedded Workbench IAR EW430 v6.40 or later Workaround is automatically enabled
TI MSP430 Compiler Tools (Code Composer Studio) v4.1.3 or later
MSP430 GNU Compiler (MSP430-GCC) MSP430-GCC 4.9 build 167