Hello i have seen article about reading the supply voltage from MSP430 http://www.elevendroids.com/2013/06/code-recipe-reading-msp430-power-supply-voltage-level/
It can be usefull when running on batteries however i am not able to find anything suitable to use for TM4C123. The system DEFINES carries another names and the code can not be used.
I have only used Energia for programming my LM4F120.
If anyone have some experience in reading the internall VCC a and Voltage Reference to compute supply voltage level on TM4C123 I would be thankfull.