/* Read switches and use the data to set LEDs for TI Tiva LaunchPad
 * with EduPad.  
 * 
 * On EduPad board, PB3-PB0 are connected to the four LEDs.
 * Switches are connected to PD3-PD0
 * S1 - PD0
 * S2 - PD1
 * S3 - PD2
 * S4 - PD3
 *
 * Built and tested with Keil MDK-ARM v5.24a and TM4C_DFP v1.1.0
 */

#include "TM4C123GH6PM.h"

int main(void) {
    volatile unsigned char readback;
    unsigned char data;

    // enable PORTB 3-0 as output
    SYSCTL->RCGCGPIO |= 0x02;       // enable clock to GPIOB
    readback = SYSCTL->RCGCGPIO;    // make sure the colock is enabled
    GPIOB->DIR |= 0x0F;             // set PORTB 3-0 as output pins
    GPIOB->DEN |= 0x0F;             // set PORTB 3-0 as digital pins

    // enable PORTD 3-0 as input
    SYSCTL->RCGCGPIO |= 0x08;       // enable clock to GPIOD
    readback = SYSCTL->RCGCGPIO;
    GPIOD->DIR &= ~0x0F;            // set pin 3-0 as input
    GPIOD->AMSEL &= ~0x0F;          // disable analog functions
    GPIOD->DEN |= 0x0F;             // set pin 3-0 as digital pins

    for (;;) {
        data = GPIOD->DATA;         // read the switches and write to LEDs
        GPIOB->DATA = data;
    }
}