Question

Write C code that initializes TM4C Port A, so pins 5, 4 and 3 are output. Comment your code to explain each initialization step clearly. Make the initialization friendly.

Answer 1

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reruired code in c:

Note:

here we take a function that takes a 3-bit parameters from 0 to 7

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#define GPIO_PORTE_DATA_R (((volatile unsigned long )0x40024000))
#define GPIO_PORTE_DIR_R (((volatile unsigned long )0x40024400))
#define GPIO_PORTE_AFSEL_R (((volatile unsigned long )0x40024420))
#define GPIO_PORTE_PUR_R (((volatile unsigned long )0x40024510))
#define GPIO_PORTE_DEN_R (((volatile unsigned long )0x4002451C))
#define GPIO_PORTE_CR_R (((volatile unsigned long )0x40024524))
#define GPIO_PORTE_AMSEL_R (((volatile unsigned long )0x40024528))
#define GPIO_PORTE_PCTL_R (((volatile unsigned long )0x4002452C))
#define SYSCTL_RCGC2_R (((volatile unsigned long )0x400FE108))

// 2. Declarations Section
// Global Variables
unsigned long sw; // input from PF4
unsigned long Out; // outputs to PF3,PF2,PF1 (multicolor LED)

// Function Prototypes
void PortE_Init(void);
void Delay(void);

int main(void){   
PortE_Init(); // Call initialization of port E
while(1){
sw = GPIO_PORTE_DATA_R&0x08; // read PE4 into sw
if(sw == 0x00){ // if switch is pressed
GPIO_PORTE_DATA_R = 0x02; // LED is green
} else{   
GPIO_PORTE_DATA_R = 0x04; // LED is red
}
Delay(); // wait 0.1 sec
GPIO_PORTE_DATA_R = 0x01; // LED is blue
Delay(); // wait 0.1 sec
}
}

// Subroutine to initialize port E pins for input and output
// PE3 is an input from a switch SW
// PE2, PE1, PE0 are outputs to the LED

void PortE_Init(void){ volatile unsigned long delay;
SYSCTL_RCGC2_R |= 0x00000010; // 1) E clock
delay = SYSCTL_RCGC2_R; // delay
GPIO_PORTE_CR_R = 0x2F; // allow changes to PE5,3-0
GPIO_PORTE_AMSEL_R = 0x00; // 3) disable analog function
GPIO_PORTE_PCTL_R = 0x00000000; // 4) GPIO clear bit PCTL
GPIO_PORTE_DIR_R |= 0x08; // 5) PE3 input
GPIO_PORTE_DIR_R &=~ 0x07; // 5) PE2,PE1,PE0 output
GPIO_PORTE_AFSEL_R = 0x00; // 6) no alternate function
GPIO_PORTE_PUR_R = 0x08; // enable pullup resistors on PE3
GPIO_PORTE_DEN_R = 0x0F; // 7) enable digital pins PE3-PE0   
}

// Subroutine to wait 0.1 sec

void Delay(void){unsigned long volatile time;
time = 727240*200/91; // 0.1sec
while(time){
time--;
}
}