System design guidelines from Texas Instruments for the TM4C129x Tiva C series microcontrollers, app note here (PDF!):
The Tiva™ C series TM4C129x microcontrollers are highly-integrated system-on-chip (SOC) devices with extensive interface and processing capabilities. Consequently, there are many factors to consider when creating a schematic and designing a circuit board. By following the recommendations in this design guide, you will increase your confidence that the board will work successfully the first time it is powered it up.