CPU46
CPU Module
Category
Functional
Function
POPM peforms unexpected memory access and can cause VMAIFG to be set
Description
When the POPM assembly instruction is executed, the last Stack Pointer increment is
followed by an unintended read access to the memory. If this read access is performed
on vacant memory, the VMAIFG will be set and can trigger the corresponding interrupt
(SFRIE1.VMAIE) if it is enabled. This issue occurs if the POPM assembly instruction is
performed up to the top of the STACK.
Workaround
If the user is utilizing C, they will not be impacted by this issue. All TI/IAR/GCC pre-built
libraries are not impacted by this bug. To ensure that POPM is never executed up to the
memory border of the STACK when using assembly it is recommended to either
1. Initialize the SP to
a. TOP of STACK - 4 bytes if POPM.A is used
b. TOP of STACK - 2 bytes if POPM.W is used
OR
2. Use the POPM instruction for all but the last restore operation. For the the last restore
operation use the POP assembly instruction instead.
For instance, instead of using:
POPM.W #5,R13
Use:
POPM.W #4,R12
POP.W R13
Refer to the table below for compiler-specific fix implementation information.
IDE/Compiler
Version Number
Notes
IAR Embedded Workbench
Not affected
C code is not impacted by this bug.
User using POPM instruction in
assembler is required to implement
the above workaround manually.
TI MSP430 Compiler Tools (Code
Composer Studio)
Not affected
C code is not impacted by this bug.
User using POPM instruction in
assembler is required to implement
the above workaround manually.
MSP430 GNU Compiler (MSP430-
GCC)
Not affected
C code is not impacted by this bug.
User using POPM instruction in
assembler is required to implement
the above workaround manually.
Advisory Descriptions
12
MSP430F67491 Microcontroller
SLAZ504AC – JANUARY 2013 – REVISED MAY 2021
Copyright © 2021 Texas Instruments Incorporated
