CCS/MSP432P401R: Variables Are Changed Without Setting

Yu-Chuan,

I would suggest setting a watchpoint on the variable.  A watchpoint is a type of breakpoint that you can configure to halt when an address or variable is written to. 

Could be something is writting to it that you are not aware.  Could be an overflow issue.  Here are some resources that may help track down the issue:

https://dev.ti.com/tirex/explore/node?node=ABOji8.duIdHhzsJkKch3A__FUz-xrs__LATEST

https://dev.ti.com/tirex/explore/node?node=AOy1zjoxkuPsN0EDD.LmQw__FUz-xrs__LATEST

https://www.youtube.com/watch?v=JlHLqzsb3D4

https://dev.ti.com/tirex/explore/node?node=AI6Jk93wA.OZd6xU.x.PHw__FUz-xrs__LATEST&search=stack%20overflow

Regards,

John

Hi John,

Thanks for offering the way to debug.

In the Debug mode with the watchpoint, the variables are not changed besides the setting.

But after I press Terminal of debug, let hardware run by itself, the variables got changed.

The result of the change is out of the setting range.

In the project, the setting range of the variable that got changed is 0x1000 to 0x18C8.

Once the variable was changed, the value became 0x0000.

The other variable is use as flag, and I made the value of the variable is 0 or 1.

It is changed into a strange value, and the value were not the same every time when the trouble happened.

(I showed them on the LCD of hardware, so I could know the values of the variables)

The troubles never happen if I used watchpoint that you told me.

Please let me know what I can do to solve the trouble next?

BR,

Yu-Chuan, Chen

Yu-Chuan,

One thing I would try would be to increase your stack size.

What you are describing could be stack overflow. However that should happen regardless of whether you are running in the debugger or not.

https://www.microcontrollertips.com/faq-avoiding-stack-overflow-embedded-processors/

Regards,

John

Hi John,

This is the first time I met this problem, thanks for your information.

What can I actually do to solve the problem of stack overflow?

Or are there any options that I can adjust to increase stack size in CCS or with MSP432?

BR,

Yu-Chuan, Chen

Yu-Chuan,

You can adjust the stack size in the project options here:

Regards,

John

Hi John,

Thanks for the answer and I will try it.

Before your reply, I tried to make a change with the amount of variables and it the trouble did not happen.

I have no idea if the way can solve the problem or not.

If the problem is lack of the buffer, I should reduce the amount of the variable to make it more space, right?

There is a variable array in the project named UART_Data[50].

I changed it into UART_Data[30] but the trouble still happened.

I changed it into UART_Data[80], the trouble did not happened.

I think it is strange and I can not understand why it happened like this.

BR,

Yu-Chuan Chen

Yu-Chuan Chen,

I would have expected the larger array to produce the overflow.  I would still go ahead and increase the stack size and see if that helps.  Assuming these are local variables.

Regards,

John

Also, very carefully inspect any code that uses pointers. Look especially carefully at any code that loops through arrays to make sure you don't access beyond the bounds of the array.

One other kind of bug that can cause this is to allocate enough space for a string, but forget to allocate space for the '\0' at the end.

Hi John and Keith,

John,

I will keep trying and letting you know the results.

Actually, the variables are global variables.

Keith,

The array is not for the string but for UCSI_Ax communicate.

BR,

Yu-Chuan