This document describes Lab 3 of an embedded systems course. It introduces header files, constants, variables and functions used to initialize and control an MCU's peripherals like LEDs, timers, UART, and ADC. The code configures the MCU's clock, enables interrupts, and implements a state machine to control the LEDs and read the ADC based on UART input from a user. Functions are defined to initialize each peripheral and an ISR handles timer interrupts.

1. Lab 3
EENG 3910: Project V - Digital Signal
Processing System Design
9/28/2015
Joseph Chandler
University of North Texas
College of Engineering
Electrical Engineering

2. Introduction
Lab 3 continuesthe studyof the TIVA C SeriesTM4C123G MicrocontrollerandCCSsoftware.The lab
introducesmore software driverlibrariesanddifferenttypesof systemcontrols.The analogtodigital
converter(ADC) API andsystemcontrols are the mainfocusof the lab.
Results and Discussions
Problem 1
#include <stdint.h>
Thisline containsthe headerfile forvariabledefinitions.The headerfileisalreadydefinedinthe CCS
software.Examplesof the valuesare bitsize,precision,andsignedorunsignedintegers.
#include <stdbool.h>
Thisline contains the headerfile forBooleandefinitions.The headerfile isalreadydefinedinthe CCS
software.The file definitionsare usedforoperations,comparingvariables,andprogramcontrol flow.
#include "inc/tm4c123gh6pm.h"
Thisline containsthe headerfile forthe TM4C123GH6PM microcontroller.The headerfile ispart-
specificandcontainsmacrosand definitionstosimplifyprogrammingthe peripheral'sregistersand
interruptcontrol.Thisiscontainedinthe incdirectory.The .c file forthe TM4C123GH6PM
microcontrollerisincludedinthe projectfolderfordirectaccess.
#include "inc/hw_memmap.h"
Thisline containsthe headerfile forthe TivaCSeriesdevice memorymapdefinitions.The headerfile
containsmanyof the same definitionsusedfordirectregisteraccess.The headerfilecontainsmacros
and definitionstosimplifyprogrammingthe peripheral'sregistersandinterruptcontrol.Thisis
containedinthe incdirectory.The definitionsare usedbydriverlibrariesandare hiddenfromthe
programmer.
#include "inc/hw_types.h"
Thisline containsthe headerfile forcommontypesandmacros.The headerfile containsmanyof the
same definitionsusedfordirectregisteraccess.Thisiscontainedinthe incdirectory.The definitionsare
usedbydriverlibrariesandare hiddenfromthe programmer.The valuesare a wide varietyof general
use for itemssuchas arithmetic,clocktiming,file recognition,anddevicerecognition.
#include "driverlib/sysctl.h"
Thisline containsthe headerfile forthe System Control APIdefinitionsandmacros.The headerfile isin
the directory"driverlib"of the CCSsoftware.The file isconsideredpartof the currentprogram when

3. "#include"isstatedbefore the name of the headerfile.The driversprovide guidedcontrol of the
peripheralsandallowsforquickapplication.Enablingperipheralsisanexample of thiscontrol.
#include "driverlib/interrupt.h"
Thisline containsthe headerfile forthe SystemControl APIdefinitionsandmacros.The headerfile isin
the directory "driverlib"of the CCSsoftware.The driversprovideguidedcontrol of the peripheralsand
allowsforquickapplication.Enablingperipheralsisanexampleof thiscontrol.
#include "driverlib/gpio.h"
Thisline containsthe headerfile forGPIOAPIdefinitionsandmacros.The headerfile isinthe directory
"driverlib"of the CCSsoftware.The driverprovidesasetof functionstocontrol the inputand output
module.
#include "driverlib/timer.h"
Thisline containsthe headerfile forTimerAPIdefinitionsandmacros.The headerfile isinthe directory
"driverlib"of the CCSsoftware.The driversprovide quickcontrol of the peripheralsandallowsforquick
application.The timerAPIprovidesasetof functionsforusingthe timermodule.
#include "driverlib/pin_map.h"
Thisline containsthe headerfile forpin_mapAPIdefinitionsandmacros.The headerfile isinthe
directory"driverlib"of the CCSsoftware.The file isconsideredpartof the current programwhen
"#include"isstatedbefore the name of the headerfile.The driversprovide quickcontrol of the
peripheralsandallowsforquickapplication.The pin_map APIprovidesamapof the peripheral topin
configuration.
#include "driverlib/uart.h"
Thisline containsthe headerfile forUART (Universal AsynchronousReceiver/Transmitter) API
definitionsandmacros.The headerfile isinthe directory"driverlib"of the CCSsoftware.The drivers
provide quickcontrol of the peripheralsandallowsforquickapplication.The UARTAPIprovidesase tof
functionsforusingthe TIVA UART module.
#include "driverlib/adc.h"
Thisline containsthe header file forADC(Analog-to-Digital)APIdefinitionsandmacros.The header file
isin the directory"driverlib"of the CCSsoftware.The driversprovidequickcontrol of the peripherals
and allowsforquickapplication.The ADCAPIprovidesasetof functionsforusingthe TIVA ADCmodule.
#include "utils/uartstdio.h"
Thisline containsthe header file forUART.The header file isinthe directory "utils"of the CCS
software.The utilityprovidesquickcontrol of the peripheralsandallowsforquickapplication.The file

4. containsprototypesforthe UART console functions.Onbuildingthe project,the .cfile hadtobe added
manuallytolinkthe filestogether.
#define TIMER0_FREQ 2
Createsa constantusedfor frequencyinthe TimerAPImacrowitha value of 2 Hz.
#define UART0_BAUDRATE 115200
Createsa constantusedfor baudrate inthe UART APImacro witha of value 115200 bps.
#define ADC0_SEQ_NUM 0
Createsa constantusedfor the ADCsample sequence number.
#define RED_LED GPIO_PIN_1
Createsa constantfor pin1 inthe GPIO APImodule thatdisplaysthe redLED.
#define BLUE_LED GPIO_PIN_2
Createsa constantfor pin2 inthe GPIO APImodule thatdisplaysthe blue LED.
#define GREEN_LED GPIO_PIN_3
Createsa constantfor pin3 inthe GPIO APImodule thatdisplaysthe greenLED.
#define NUM_DISP_TEXT_LINE 4
Createsa constantfor the numberof linesof textdisplayinthe characterpointer"disp_text"witha
value of 4.
void init_LEDs(void);
Thisline declaresthe functionprototype "init_LEDs".Declarationatthispointgivesthe actual functiona
global scope.Anyotherfunction,header,or.c file containedinthissource file isgivenaccesstothe
functionandaccessible bythe function.
void init_timer(void);
Thisline declaresthe functionprototype " init_timer".Declarationatthispointgivesthe actual function
a global scope.Anyotherfunction,header,or.cfile containedinthissource fileisgivenaccesstothe
functionandaccessible bythe function.
void Timer0_ISR(void);
Thisline declaresthe functionprototype " Timer0_ISR".Declarationat thispointgivesthe actual
functionaglobal scope.Anyotherfunction,header,or.cfile containedinthissource fileisgivenaccess
to the functionandaccessible bythe function.
void init_UART(void);

5. Thisline declaresthe functionprototype " init_UART".Declarationatthispointgivesthe actual function
a global scope.Anyotherfunction,header,or.cfile containedinthissource fileisgivenaccesstothe
functionandaccessible bythe function.
void init_ADC(void);
Thisline declaresthe functionprototype " init_ADC".Declarationatthispointgivesthe actual function
a global scope.Anyotherfunction,header,or.cfile containedinthissource fileisgivenaccesstothe
functionandaccessible bythe function.
extern void UARTStdioIntHandler(void);
Thisline declaresafunctionprototype of type "extern".Thisinformsthe microprocessorthatitneedsto
access a functionthatexistsoutsideof thissource file.The uartstdio.cfileisincludedinthe project
folderfordirectaccess.The uartstdio.cfile hasadditional functionsforthe UARTconsole.Thisparticular
functionhandlesinterruptsfromthe UART.The UART has a transmitandreceive bufferthatisusedfor
data transfersbetweenthe microprocessorandthe puttyconsole.
uint32_t sys_clock;
Createsan unsigned32-bitglobal variable forthe systemclock.
uint8_t cur_LED = RED_LED;
Createsan unsigned8-bitglobal variable forthe redLED.
const char *disp_text[NUM_DISP_TEXT_LINE] = {
"n",
"UART and LED Demon",
"H: help, R: red, G: green, B: blue, T: temperature.n",
"> " };
Thisline createsa pointer fora systemmessage communicated tothe userviaputtyconsole.
uint32_t cur_temp=0, cur_temp_C=0, cur_temp_F=0;
Createsan unsigned32-bitglobal variable forthe temperatures.
int main(void){
The main processcallsandacts on variables,macros,definitions,andothersystemfunctions.
uint32_t i;
Createsan unsigned32-bitvariable forloops.
unsigned char user_cmd;
Createsan unsignedcharactervariable foruserinput.

6. SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);
SystemControl ClockSetsetsthe clockingof the device.Osc_Mainconfiguresthe oscillatorsource.
XTAL_16MHZ usesa 16 MHZ crystal clock. USE_PLL is a phase lockedloop at400MHZ. SYSDIV_5 divides
the clock bythe numberspecifiedgivingcontrol of the frequency.
sys_clock = SysCtlClockGet();
Thisline retrievesthe processorclockrate andassignsit toa variable.
init_LEDs();
InitializesLEDconfigurationandenables by calling the function definition.
init_ADC();
InitializesADCconfigurationandenables by calling the function definition.
init_UART();
InitializesUARTconfigurationandenables by calling the function definition.
init_timer();
InitializesTimerconfigurationandenables by calling the function definition.
IntMasterEnable();
ThisNVICAPIfunctionenablesinterruptsfromthe microprocessortointerruptcontroller.
TimerEnable(TIMER0_BASE, TIMER_A);
ThisTIMER API functionenablesoperationof the timermodule.
for(i=0; i<NUM_DISP_TEXT_LINE; i++)
Thisline isa for loopto displayprogrammessage onconsole.
UARTprintf(disp_text[i]);
Thisfunctionprintsthe message onthe console.
while(1) {
The while loopprovidesacontinuousloopwhensetto"1".
if(UARTRxBytesAvail())
If the UART has available userinput.
user_cmd = UARTgetc();

7. Thisline retrievesthe userinputandstoresitina variable.
else
user_cmd = 0;
Else,the usercommand variable issetto 0.
switch(user_cmd){
Switchcase for the userinputdata.
case 'r':
Switchcase for red.
case ' ':
Switchcase for empty.
case 'H':
Switchcase for H.
case 'h':
Switchcase for h.
for(i=0; i<NUM_DISP_TEXT_LINE; i++)
Switchcase displayforlines87-90 is a for looptodisplayconsole message touserviaputty.
UARTprintf(disp_text[i]);
Thisfunctionprintsthe message onthe puttyconsole.
break;
Switchcase break.
case 'R':
Switchcase for redled.
case 'r':
Switchcase for redled.
cur_LED = RED_LED;
Storesthe red ledincurrentledvariable.

8. UARTprintf("n> ");
Thisfunctionprintsa newline witha> on the console.
break;
Switchcase break.
case 'B':
Switchcase for blue led.
case 'b':
Switchcase for blue led.
cur_LED = BLUE_LED;
Storesthe blue ledincurrentledvariable.
UARTprintf("n> ");
Thisfunctionprintsa newline witha> on the console.
break;
Switchcase break.
case 'G':
Switchcase for greenled.
case 'g':
Switchcase for greenled.
cur_LED = GREEN_LED;
Storesthe greenledincurrentledvariable.
UARTprintf("n> ");
Thisfunctionprintsa newline witha> on the console.
break;
Switchcase break.
case 'T':
Switchcase for temperature sensor.

9. case 't':
Switchcase for temperature sensor.
ADCProcessorTrigger(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionenablesthe processortotriggerthe ADC sequence capture.
while(!ADCIntStatus(ADC0_BASE, ADC0_SEQ_NUM, false)) {
Thisfunctionandwhile loopenablesthe ADCinterrupttocapture dataas long as data exists.
ADCIntClear(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionclearsthe ADCinterruptfromoccurringagain.
ADCSequenceDataGet(ADC0_BASE, ADC0_SEQ_NUM, &cur_temp);
Thisfunctionassignsthe captureddatato a variable.
cur_temp_C = (1475 - (2475*cur_temp)/4096)/10;
Thisvariable isassignedthe Celsiustemperatureconversion.
cur_temp_F = (cur_temp_C*9 + 160)/5;
Thisvariable isassignedthe Fahrenheit temperature conversion.
UARTprintf("nTemp = %dC = %dFn> ", cur_temp_C, cur_temp_F);
Thisfunctionprintsthe temperature conversions onthe puttyconsole.
void init_LEDs(void)
User-definedfunctiondefinitionforinitializingLEDs.The functionreturnsavalue of 0.
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
The SystemControl APIfunctionenablesthe GPIOportF peripheral.
GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);
The GPIO APIfunctionconfigurespins1,2, or 3 of port F for use as GPIOoutputs.
void init_timer(void)
User-definedfunctiondefinitionforinitializingTimer.The functionreturnsavalue of 0.
SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
The SystemControl APIfunctionenablesTIMER0 peripheral.

10. TimerConfigure(TIMER0_BASE, TIMER_CFG_PERIODIC);
The TimerAPI functionconfiguresthe timerasa 32-bitfull-widthperiodictimer.
TimerLoadSet(TIMER0_BASE, TIMER_A, sys_clock/TIMER0_FREQ -1);
The TimerAPI functionspecifiesthe base addressforconfiguration,the correctname fora full-width
timer,andthe load value specifiedbyuser-definedconstants.
IntRegister(INT_TIMER0A, Timer0_ISR);
The NVICAPIfunctionregistersthe "TIMER0_ISR"functiontobe calledwhenthe "TIMER0A"interruptis
enabled.
IntEnable(INT_TIMER0A);
The NVICAPIfunctionenables"TIMER0A"asa full-widthtimer tobe usedforthe interruptfunction
process.
TimerIntEnable(TIMER0_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionenablesthe specifictimermodule(TIMER0_Base) forthe timerinterruptsource.
The bit maskof the interruptsource tobe enabledis"TIMER_TIMA_TIMEOUT".
void init_UART(void)
User-definedfunctiondefinitionforinitializingUART.The functionreturnsavalue of 0.
SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
The SystemControl APIfunctionenablesthe UART0 peripheral.
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
The SystemControl APIfunctionenablesthe GPIOA peripheral.
GPIOPinConfigure(GPIO_PA0_U0RX);
The GPIO APIfunctionconfiguresthe alternate functionof aGPIO pin.GPIOPort A's pinmux is
configuredforthe UART peripheral.Pin0is configuredforthe UARTreceiverbuffer.
GPIOPinConfigure(GPIO_PA1_U0TX);
The GPIO APIfunctionconfiguresthe alternate functionof aGPIO pin.GPIOPort A's pinmux is
configuredforthe UART0 peripheral.Pin1isconfiguredforthe UART transmitterbuffer.
GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
The GPIO APIfunctionconfigurespinsforuse bythe UART peripheral.GPIOPortA will be the peripheral
usedforUART communication.Pins1and2 of port A are available.

11. IntRegister(INT_UART0, UARTStdioIntHandler);
The NVICAPIfunctionregistersthe "UARTStdioIntHandler"functiontobe calledwhen the "UART0"
interruptisenabled.
UARTStdioConfig(0, UART0_BAUDRATE, sys_clock);
The UART driverfunctionconfiguresthe UARTforinput/output.UARTPort0 isthe base that will be
used.The user-definedconstant"UART0_BAUDRATE"isthe bitrate forthe UART and the user-defined
constant "sys_clock"isthe frequencyusedforthe source clockof the UART module.
void init_ADC(void)
User-definedfunctiondefinitionforinitializingADC.The functionreturnsavalue of 0.
SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
The SystemControl APIfunctionenablesthe ADC0peripheral.
ADCSequenceConfigure(ADC0_BASE, ADC0_SEQ_NUM, ADC_TRIGGER_PROCESSOR, 0);
The ADC APIfunctionspecifiesthe base addressforconfiguration,the sequence number,the trigger
type,andorder importance.
ADCSequenceStepConfigure
(ADC0_BASE, ADC0_SEQ_NUM, 0, ADC_CTL_TS|ADC_CTL_IE|ADC_CTL_END);
The ADC APIfunctionspecifiesthe base addressforconfiguration,,the sequence number,order
importance,andsequence configurationoptionsfortemperaturesensor,interrupts,andend.
ADCSequenceEnable(ADC0_BASE, ADC0_SEQ_NUM);
The ADC APIfunctionenablesthe specificsequence numberforthe selectedbase.
void Timer0_ISR(void)
User-definedfunctiondefinitionforinterrupthandler. The functionreturnsavalue of 0.
TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionclearsthe timerinterruptsources.TIMER0 isthe base specifiedand
"TIMER_TIMA_TIMEOUT" isthe bitmaskfor the interruptsource cleared.
if(GPIOPinRead(GPIO_PORTF_BASE, GPIO_PIN_2)) {
If the GPIOAPIfunctionreadspins1,2, or 3 fromport F, readline 194.
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, 0);
The GPIO APIfunctionwritesa0 to pins1,2, or 3.

12. else {
Else the GPIO API function...
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, cur_LED);
Writesthe value of the variable "cur_LED" to the correct pin.
Figure 1 Putty Display
Problem 2
#define TIMER1_FREQ 0.5
I defined anothertimerfrequency constant(global) forthe temperature todisplayevery2seconds.
void init_timer1(void);
I createda prototype fortimer1'sinitialization.
void Timer1_ISR(void);
I createda prototype fortimer1'sinterrupt.
init_timer1();
I calledthe init_timer1functiontoinitializethe new timer.
TimerEnable(TIMER1_BASE, TIMER_A);
I enabledthe timermoduleforoperation.
while(1) {
While loopprovidescontinuousloop.
void init_timer1(void)
User-definedfunctiondefinitionfor initializingTimer.The functionreturnsavalue of 0.
SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER1);
The SystemControl APIfunctionenablesthe timer1peripheral.

13. TimerConfigure(TIMER1_BASE, TIMER_CFG_PERIODIC);
The TimerAPI functionconfiguresthe timer1asa 32-bit full-widthperiodictimer.
TimerLoadSet(TIMER1_BASE, TIMER_A, sys_clock/TIMER1_FREQ );
The TimerAPI functionspecifiesthe base addressforconfiguration,the correctname fora full-width
timer,andthe load value specifiedbyuser-definedconstants.
IntRegister(INT_TIMER1A, Timer1_ISR);
The NVICAPIfunctionregistersthe "TIMER1_ISR"functiontobe calledwhenthe "TIMER0A"interruptis
enabled.
IntEnable(INT_TIMER1A);
The NVICAPIfunctionenables"TIMER1A"asa full-widthtimer tobe usedforthe interruptfunction
process.
TimerIntEnable(TIMER1_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionenablesthe specifictimermodule(TIMER1_Base) forthe timerinterruptsource.
The bit maskof the interruptsource tobe enabledis "TIMER_TIMA_TIMEOUT".
void Timer1_ISR(void)
User-definedfunctiondefinitionforinterrupthandler.The functionreturnsavalue of 0.
TimerIntClear(TIMER1_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionclearsthe timerinterruptsources.TIMER1 isthe base specifiedand
"TIMER_TIMA_TIMEOUT" isthe bitmaskfor the interruptsource cleared.
ADCProcessorTrigger(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionenablesthe processortotriggerthe ADC sequence capture.
while(!ADCIntStatus(ADC0_BASE, ADC0_SEQ_NUM, false)) {
Thisfunctionandwhile loopenablesthe ADCinterrupttocapture dataas longas data exists.
ADCIntClear(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionclearsthe interruptfromoccurringagain.
ADCSequenceDataGet(ADC0_BASE, ADC0_SEQ_NUM, &cur_temp);
Thisfunctionassignsthe captureddatato a variable.
cur_temp_C = (1475 - (2475*cur_temp)/4096)/10;

14. Thisvariable isassignedthe Celsiustemperatureconversion.
cur_temp_F = (cur_temp_C*9 + 160)/5;
Thisvariable isassignedthe Fahrenheittemperatureconversion.
UARTprintf("nTemp = %dC = %dFn> ", cur_temp_C, cur_temp_F);
Thisfunctionprintsthe temperature conversionsonthe puttyconsole.
Figure 2 Putty Display
Problem 3
FPU isusedfor higherprecision calculationsandvariablesforstoringthe resultsinmemory.The
functionFPULazyStackingEnable allocatesspace onthe stackfor floating-pointstorage.The processor
onlysavesthe contextif itisinvolvedinaninstruction.The interrupthandlerdoesnotsave floating-
pointdata and takesmore time toconfigure the stackfor itsuse.
There isa software driverlibrarythatprovidesFPUAPI.The headerfile isincludedatthe beginningof
the source file.A constant isalso definedforthe space allocatedforstorage.The temperature variables
are savedas floatingpointastheywill be usedmultiple timestodisplaythe temperature if needed.A
variable of type char array isessentiallyusedforthe stringof charactersdisplayingthe temperatures.
The functionsnprintf storesthe formattedtemperaturesinabufferstringforformatdeclarationand
ease of use withrepetition.
Problem 4
#include <stdio.h>
The standard input/outputlibrarywasaddedforthe functionsnprintf.

15. #include "driverlib/fpu.h"
The FPU driverlibrarywasaddedforthe FPU APIavailability.
#define TIMER1_FREQ .5
I definedanothertimerfrequencyconstant(global) forthe temperature todisplayevery2seconds.
#define TEMP_STR_LEN 20
The constant wasrepeatedfromLab3_3 forthe lengthof the string.
uint32_t cur_temp=0;
The constant was repeatedfromLab3_3 for the unsigned32-bitinteger.
float cur_temp_C=0, cur_temp_F=0;
The constants wasrepeatedfromLab3_3 for the floating-pointtemperatures.
char temp_str[TEMP_STR_LEN];
The constant was repeatedfromLab3_3 for the char array.
void Timer1_ISR(void)
User-definedfunctiondefinitionforinterrupthandler.The functionreturnsavalue of 0.
TimerIntClear(TIMER1_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionclears the timerinterruptsources.TIMER1 isthe base specifiedand
"TIMER_TIMA_TIMEOUT" isthe bitmaskfor the interruptsource cleared.
FPUEnable();
I enabledthe FPUmodule foroperation.
FPULazyStackingEnable();
I enabledthe floating-pointlazystackingformemoryaccess.
ADCProcessorTrigger(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionenablesthe processortotriggerthe ADC sequence capture.
while(!ADCIntStatus(ADC0_BASE, ADC0_SEQ_NUM, false)) {
Thisfunctionandwhile loopenablesthe ADCinterruptto capture dataas longas data exists.
ADCIntClear(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionclearsthe interruptfromoccurringagain.

16. ADCSequenceDataGet(ADC0_BASE, ADC0_SEQ_NUM, &cur_temp);
Thisfunctionassignsthe captureddatato a variable.
cur_temp_C = (1475 - (2475*cur_temp)/4096)/10;
Thisvariable isassignedthe Celsiustemperatureconversion.
cur_temp_F = (cur_temp_C*9 + 160)/5;
Thisvariable isassignedthe Fahrenheittemperatureconversion.
snprintf(temp_str, TEMP_STR_LEN, "%.1fC = %.1fF", cur_temp_C, cur_temp_F);
Thisfunctionconfiguresandregistersavariable forfrequentuse of printingfloating-point.
UARTprintf("nTemp = %sn> ", temp_str);
Thisfunctionprintsthe temperature conversionsonthe puttyconsole fromthe configuredvariable.
Figure 3 Putty Display
Problem 5
#include <stdint.h>
Thisline containsthe headerfile forvariabledefinitions.Examplesof the valuesare bitsize,precision,
and signedorunsignedintegers.
#include <stdbool.h>
Thisline containsthe headerfile forBooleandefinitions.The headerfile isalreadydefinedinthe CCS
software.The file definitionsare usedforoperations,comparingvariables,andprogramcontrol flow.
#include "inc/tm4c123gh6pm.h"
Thisline containsthe headerfile forthe TM4C123GH6PM microcontroller.The headerfile ispart-
specificandcontainsmacrosand definitionstosimplifyprogrammingthe peripheral'sregistersand
interruptcontrol.Thisiscontainedinthe incdirectory.The .c file forthe TM4C123GH6PM
microcontrollerisincludedinthe projectfolderfordirectaccess.
#include "inc/hw_memmap.h"

17. Thisline containsthe headerfile forthe TivaCSeriesdevice memorymapdefinitions.The headerfile
containsmanyof the same definitionsusedfordirectregisteraccess.The headerfilecontainsmacros
and definitionstosimplifyprogrammingthe peripheral'sregistersandinterruptcontrol.Thisis
containedinthe incdirectory.The definitionsare usedbydriverlibrariesand are hiddenfromthe
programmer.
#include "inc/hw_types.h"
Thisline containsthe headerfile forcommontypesandmacros.The headerfile containsmanyof the
same definitionsusedfordirectregisteraccess.Thisiscontainedinthe incdirectory.The definitionsare
usedbydriverlibrariesandare hiddenfromthe programmer.The valuesare a wide varietyof general
use for itemssuchas arithmetic,clocktiming,file recognition,anddevicerecognition.
#include "driverlib/sysctl.h"
Thisline contains the headerfile forthe SystemControl APIdefinitionsandmacros.The headerfile isin
the directory"driverlib"of the CCSsoftware.The driversprovideguidedcontrol of the peripheralsand
allowsforquickapplication.Enablingperipheralsisanexampleof thiscontrol.
#include "driverlib/interrupt.h"
Thisline containsthe headerfile forthe SystemControl APIdefinitionsandmacros.The headerfile isin
the directory"driverlib"of the CCSsoftware.The driversprovideguidedcontrol of the peripheralsand
allowsforquickapplication.Enablingperipheralsisanexampleof thiscontrol.
#include "driverlib/gpio.h"
Thisline containsthe headerfile forGPIOAPIdefinitionsandmacros.The headerfile isinthe directory
"driverlib"of the CCSsoftware.The driverprovidesasetof functionstocontrol the inputand output
module.
#include "driverlib/timer.h"
Thisline containsthe headerfile forTimerAPIdefinitionsandmacros.The headerfile isinthe directory
"driverlib"of the CCSsoftware. The driversprovide quickcontrol of the peripheralsandallowsforquick
application.The timerAPIprovidesasetof functionsforusingthe timermodule.
#include "driverlib/pin_map.h"
Thisline containsthe headerfile forpin_mapAPIdefinitionsandmacros.The headerfile isinthe
directory"driverlib"of the CCSsoftware.The driversprovidequickcontrol of the peripheralsandallows
for quickapplication.The pin_map APIprovidesamapof the peripheral topinconfiguration.
#include "driverlib/uart.h"
Thisline containsthe headerfile forUART(Universal AsynchronousReceiver/Transmitter) API
definitionsandmacros.The headerfile isinthe directory"driverlib"of the CCSsoftware.The drivers

18. provide quickcontrol of the peripheralsandallowsforquickapplication.The UARTAPIprovidesasetof
functionsforusingthe TIVA UART module.
#include "driverlib/adc.h"
Thisline containsthe header file forADC(Analog-to-Digital)APIdefinitionsandmacros.The header file
isin the directory"driverlib"of the CCSsoftware.The driversprovidequickcontrol of the peripherals
and allowsforquickapplication.The ADCAPIprovidesasetof functionsforusingthe TIVA ADCmodule.
#include "utils/uartstdio.h"
Thisline containsthe header file forUART.The header file isinthe directory"utils"of the CCS
softwareThe utilityprovidesquickcontrol of the peripheralsandallowsforquickapplication.The file
containsprototypesforthe UART console functions.Onbuildingthe project,the .cfile hadtobe added
manuallytolinkthe filestogether.
#define TIMER0_FREQ 2
I definedanothertimerfrequencyconstant(global) for2Hz.
#define TIMER1_FREQ 1
I definedanothertimerfrequencyconstant(global) for1Hz.
#define ADC_PIN GPIO_PIN_0
Definedconstantforthe pinusedasinput for ADCmodule.
#define TIMER_PIN GPIO_PIN_4
Definedconstantforthe pinusedasinput for Timermodule.
void init_timer(void);
I createda prototype fortimer0'sinitialization.
void Timer0_ISR(void);
I createda prototype fortimer0'sinterrupt.
void init_GPIO(void);
I createda prototype fortimer0'sinitialization.
void init_timer1(void);
I createda prototype fortimer0'sinitialization.
void Timer1_ISR(void);
I createda prototype fortimer0'sinterrupt.

19. uint8_t cur_LED = RED_LED;
Createsan unsigned8-bitglobal variable forthe systemclock.
uint32_t sys_clock;
Createsan unsigned32-bitglobal variable forthe systemclock.
uint32_t analog_input;
Createsa 32-bit global variable forthe analogsample.
int main(void){
The main processcallsandacts on variables,macros,definitions,andothersystemfunctions.
unsigned char user_cmd;
Createsan unsignedcharactervariable foruserinput.
uint32_t i;
Createsan unsigned32-bitvariable forloops.
SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);
SystemControl ClockSetsetsthe clockingof the device.Osc_Mainconfiguresthe oscillatorsource.
XTAL_16MHZ usesa 16 MHZ crystal clock. USE_PLL is a phase lockedloopat400MHZ. SYSDIV_5 divides
the clock bythe numberspecifiedgivingcontrol of the frequency.
sys_clock = SysCtlClockGet();
Thisline retrievesthe processorclockrate andassignsit toa variable.
init_LEDs();
InitializesLEDconfigurationandenables by calling the function definition.
init_ADC();
InitializesADCconfigurationandenables by calling the function definition.
init_UART();
InitializesUARTconfigurationandenables by calling the function definition.
init_timer();
InitializesTimerconfigurationandenables by calling the function definition.
init_GPIO();

20. InitializesGPIOconfigurationandenables by calling the function definition.
init_timer1();
InitializesTimer1configurationand enables by calling the function definition.
IntMasterEnable();
ThisNVICAPIfunctionenablesinterruptsfromthe microprocessortointerruptcontroller.
TimerEnable(TIMER0_BASE, TIMER_A);
Enable timerwithinterruptsforLEDS.
for(i=0; i<NUM_DISP_TEXT_LINE; i++)
Thisline isa for loopto displayprogrammessage onconsole.
UARTprintf(disp_text[i]);
Thisfunctionprintsthe message onthe console.
while(1) {
The while loopprovidesacontinuousloopwhensetto"1".
if(UARTRxBytesAvail())
If the UART has available userinput.
user_cmd = UARTgetc();
Thisline retrievesthe userinputandstoresitina variable.
else
user_cmd = 0;
Else,the usercommandvariable issetto 0.
switch(user_cmd){
Switchcase for the userinputdata.
case 'r':
Switchcase for red.
case ' ':
Switchcase for empty.
case 'H':

21. Switchcase for H.
case 'h':
Switchcase for h.
for(i=0; i<NUM_DISP_TEXT_LINE; i++)
Switchcase displayforlines87-90 is a for looptodisplayconsole message touserviaputty.
UARTprintf(disp_text[i]);
Thisfunctionprintsthe message onthe puttyconsole.
break;
Switchcase break.
case 'R':
Switchcase for redled.
case 'r':
Switchcase for redled.
cur_LED = RED_LED;
Storesthe red ledincurrentledvariable.
UARTprintf("n> ");
Thisfunctionprintsa newline witha> on the console.
break;
Switchcase break.
case 'B':
Switchcase for blue led.
case 'b':
Switchcase for blue led.
cur_LED = BLUE_LED;
Storesthe blue ledincurrentledvariable.
UARTprintf("n> ");

22. Thisfunctionprintsa newline witha> on the console.
break;
Switchcase break.
case 'G':
Switchcase for greenled.
case 'g':
Switchcase for greenled.
cur_LED = GREEN_LED;
Storesthe greenledincurrentledvariable.
UARTprintf("n> ");
Thisfunctionprintsa newline witha> on the console.
break;
Switchcase break.
case 'A':
Switchcase for analogsensor.
case 'a':
Switchcase for analogsensor.
ADCProcessorTrigger(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionenablesthe processortotriggerthe ADC sequence capture.
while(!ADCIntStatus(ADC0_BASE, ADC0_SEQ_NUM, false)) {
Thisfunctionandwhile loopenablesthe ADCinterrupttocapture dataas longas data exists.
ADCIntClear(ADC0_BASE, ADC0_SEQ_NUM);
Thisfunctionclearsthe ADCinterruptfromoccurringagain.
ADCSequenceDataGet(ADC0_BASE, ADC0_SEQ_NUM, &analog_input);
Thisfunctionassignsthe captureddatato a variable.
UARTprintf("nAnalog Input = %dn> ", analog_input);

23. Thisfunctionprintsthe analoginputonthe putty console.
case 'D':
Switchcase for digital sensor.
case 'd':
Switchcase for digital sensor
TimerEnable(TIMER1_BASE, TIMER_A);
Thisfunctionenablesthe processortotriggerthe ADC sequence capture.
break;
Switchcase break.
void init_GPIO(void)
User-definedfunctiondefinitionforinitializingGPIO.The functionreturnsavalue of 0.
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
The SystemControl APIfunctionenablesthe GPIODperipheral.
GPIOPinTypeADC(GPIO_PORTD_BASE, ADC_PIN);
Thisfunctionenablesthe pinof choice tosupportADCtype configurations.
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
The SystemControl APIfunctionenablesthe GPIOEperipheral.
GPIOPinConfigure(GPIO_PE4_U5RX);
The GPIO APIfunctionconfiguresthe alternate functionof aGPIO pin.GPIOPort E's pinmux is
configuredforthe UART peripheral.Pin4is configuredforthe receivingbuffer.
GPIOPinTypeTimer(GPIO_PORTE_BASE, TIMER_PIN);
Thisfunctionenablesthe pinof choice tosupportTimertype configurations.
void init_timer1(void)
User-definedfunctiondefinitionforinitializingTimer.The functionreturnsavalue of 0.
SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER1);
The SystemControl APIfunctionenablesthe TIMER1 peripheral.
TimerConfigure(TIMER1_BASE, TIMER_CFG_PERIODIC);

24. The TimerAPI functionconfiguresthe timerasa 32-bitfull-widthperiodictimer.
TimerLoadSet(TIMER1_BASE, TIMER_A, sys_clock/TIMER0_FREQ -1);
The TimerAPI functionspecifiesthe base addressforconfiguration,the correctname fora full-width
timer,andthe load value specifiedbyuser-definedconstants.
IntRegister(INT_TIMER1A, Timer1_ISR);
The NVICAPIfunctionregistersthe "TIMER1_ISR"functiontobe calledwhenthe "TIMER0A"interruptis
enabled.
IntEnable(INT_TIMER1A);
The NVICAPIfunctionenables"TIMER1A"asa full-widthtimer tobe usedforthe interruptfunction
process.
TimerIntEnable(TIMER1_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionenables the specifictimermodule(TIMER1_Base) forthe timerinterruptsource.
The bit maskof the interruptsource tobe enabledis"TIMER_TIMA_TIMEOUT".
void Timer0_ISR(void)
User-definedfunctiondefinitionforinterrupthandler.The functionreturnsavalue of 0.
TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionclearsthe timerinterruptsources.TIMER0 isthe base specifiedand
"TIMER_TIMA_TIMEOUT" isthe bitmaskfor the interruptsource cleared.
if(GPIOPinRead(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3)) {
If the GPIOAPIfunctionreadspins1,2, or 3 fromport F, readline 209.
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, 0);
The GPIO APIfunctionwritesa0 to pins1,2, or 3.
else {
Else the GPIO APIfunction...
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, cur_LED);
Writesthe value of the variable "cur_LED" to the correct pin.
void init_timer(void)
User-definedfunctiondefinitionforinitializingTimer.The functionreturnsavalue of 0.

25. SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
The SystemControl APIfunctionenablesthe timer0peripheral.
TimerConfigure(TIMER0_BASE, TIMER_CFG_PERIODIC);
The TimerAPI functionconfiguresthe timerasa 32-bitfull-widthperiodictimer.
TimerLoadSet(TIMER0_BASE, TIMER_A, sys_clock/TIMER0_FREQ -1);
The TimerAPI functionspecifiesthe base addressforconfiguration,the correctname fora full-width
timer,andthe load value specifiedbyuser-definedconstants.
IntRegister(INT_TIMER0A, Timer0_ISR);
The NVICAPIfunctionregistersthe "TIMER0_ISR"functiontobe calledwhenthe "TIMER0A"interruptis
enabled.
IntEnable(INT_TIMER0A);
The NVICAPIfunctionenables"TIMER0A"asa full-widthtimer tobe usedforthe interruptfunction
process.
TimerIntEnable(TIMER0_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionenablesthe specifictimermodule(TIMER0_Base) forthe timerinterruptsource.
The bit maskof the interruptsource tobe enabledis"TIMER_TIMA_TIMEOUT".
void Timer1_ISR(void)
User-definedfunctiondefinitionforinterrupthandler.The functionreturnsavalue of 0.
TimerIntClear(TIMER1_BASE, TIMER_TIMA_TIMEOUT);
The TimerAPI functionclearsthe timerinterruptsources.TIMER1 isthe base specifiedand
"TIMER_TIMA_TIMEOUT" isthe bit maskfor the interruptsource cleared.
GPIOPinRead(GPIO_PORTE_BASE, TIMER_PIN);
ThisGPIO APIfunctionreadspin4 from portE.
UARTprintf("nTimer Input = %dn> ", TIMER_PIN);
Thisfunctionprintsthe timerdatato the puttyconsole.
TimerDisable(TIMER1_BASE, TIMER_A);
Thisfunctiondisablesthe timerforotherinterruptstooccur fromuserinput.
Summary and Conclusions

26. TimersandSequencesare vital control components whenutilizingthe TivaCSeriesTM4C123GH6PM
microcontroller.The timerandADChave interruptroutines usingthe NVICcontrollertoestablish
periodsforsampling.The samplesare usedinanalog-to-digital conversion.
References
TexasInstruments.(2014). TivaWarePeripheral Driver Library: User'sGuide