1. GPIO General Purpose Input/output Tiva C TM4C123GH6PM
James Boswell
Gary O’Day
Michael Whatley

2. General Information
6 GPIO ports (A,B,C,D,E, and F) combine to offer up to 43 GPIOS (depending on configuration)
Multiplexing allows pins to be used as GPIO or one of several alternate peripheral functions.
Commit control protection is provided to the JTAG/SWD (pins PC[3:0]) and non maskable interrupt pins (PD7 and PF0).
GPIO Pin states retained during hibernation mode
Digital inputs are Schmitt- triggered
Programmable control for GPIO pad configuration
pull up or pull down resistor
2,4, or 8 mA drive
Up to four pads can sink 18 mA for high current applications

3. Alternate Function Table Part 1

4. Alternate Function Table Part 2

5. GPIO Initialization General Process

6. Methods of Configuration
Direct Register method
peripherals are programmed by directly accessing memory addresses .
Software driver method
The software Driver model utilizes the TivaWare™ Peripheral Driver Library.
Pinmux Utility
Graphical user interface use to configure GPIO multiplexing

7. Direct Register Access Model
The header file, “TM4C123GH6M.h” contains all of the definitions for assigning port variables to the physical memory locations.
variable names begin with the module name and number (GPIO_PORTF) followed by register name as presented in data sheet.
for example, the DIR (direction) register combined with the GPIO_PORTF would result in the variable GPIO_PORTF_DIR_R.
Values that end in _R are used to access the value of a register
Values that end in _M represent the mask for a multi-bit field in a register
Values that end in _S represent the number of bits to shift a value in order to align it with a multi-bit field.

8. Direct Register Access Method Example
Header Files Located Here

9. Software Driver Model
The Library contains pre defined functions or APIs (Application Programming Interface)for configuring peripherals.
Header Files Located Here

10. Partial List of GPIO APIs
Complete List Found in TivaWare Peripheral Driver Library Manual (link provided in reference section).

11. PinMux Utility
Graphical user interface use to configure GPIO multiplexing
Built in protection for collision control
Protection for JTAG pins
Automatically generates c source and header files

12. PinMux Utility continued

13. Questions ?

14. References http://www.ti.com/lit/ug/spmu296/spmu296.pdf
Fall 2014 presentation by Raul Cabrera, Khaldon Batnij, Isaac Zavala