MSP432E401Y: Systick no longer running once sscanf, snprintf and other STDIO functions are called

Are you declaring things volatile?

Could you have a naming collision?

How do you you read your Systick Variable? Do you turn off interrupts when you read it?

Are you using global buffers for sscanf() or snprintf()? Could you be clobbering your Systick variable?

Did you increase the stack space - snprintf() is a real stack hog.

It is a volatile variable

I do not think it's a naming collision, as the issue only occurs with snprintf or sscanf

I am not currently turning of interrupts to read it.  I only read it in the delay function, and only write in the handler.

I don't think I would be clobbering it?  For sscanf I was reading from a fairly small string (1 character plus terminating character, but in the future would be longer), into an integer.

I did increase the stack space significantly.  How large do you think I should have it extra?

Thank you for your time.

If you are using the launchpad, you can toggle the LED in the systick handler to see if it is indeed getting stopped.

Doubling the stack should be enough.

Make sure that the buffer size matches the 'n' setting in snprintf().

I will add to Keith's comment that you also need to add significant heap size. C standard functions like printf takes up a lot of memory space. 

I always seem to forget about the heap!

The stack was already increased in size by quite a bit, but I added more to it.  I raised it to 2048 bytes, which seems insane, but it seems to work now.

I wouldn't expect to be using too terribly much given there's no recursion or anything.

Thank you for your help

You can change the heap size under linker configuration. See below.