// Serial Example

//-----------------------------------------------------------------------------
// Hardware Target
//-----------------------------------------------------------------------------

// Target Platform: EK-TM4C123GXL Evaluation Board
// Target uC:       TM4C123GH6PM
// System Clock:    40 MHz


//-----------------------------------------------------------------------------
// Device includes, defines, and assembler directives
//-----------------------------------------------------------------------------

#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include "tm4c123gh6pm.h"

#define RED_LED      (*((volatile uint32_t *)(0x42000000 + (0x400253FC-0x40000000)*32 + 1*4)))
#define GREEN_LED    (*((volatile uint32_t *)(0x42000000 + (0x400253FC-0x40000000)*32 + 3*4)))
#define PUSH_BUTTON  (*((volatile uint32_t *)(0x42000000 + (0x400253FC-0x40000000)*32 + 4*4)))

//-----------------------------------------------------------------------------
// Subroutines
//-----------------------------------------------------------------------------

// Blocking function that returns only when SW1 is pressed
void waitPbPress()
{
    while(PUSH_BUTTON);
}

// Initialize Hardware
void initHw()
{
    // Configure HW to work with 16 MHz XTAL, PLL enabled, system clock of 40 MHz
    SYSCTL_RCC_R = SYSCTL_RCC_XTAL_16MHZ | SYSCTL_RCC_OSCSRC_MAIN | SYSCTL_RCC_USESYSDIV | (4 << SYSCTL_RCC_SYSDIV_S);

    // Set GPIO ports to use APB (not needed since default configuration -- for clarity)
    // Note UART on port A must use APB
    SYSCTL_GPIOHBCTL_R = 0;

    // Enable GPIO port A and F peripherals
    SYSCTL_RCGC2_R = SYSCTL_RCGC2_GPIOA | SYSCTL_RCGC2_GPIOC | SYSCTL_RCGC2_GPIOF;

    // Configure LED and pushbutton pins
    GPIO_PORTF_DIR_R = 0x0A;  // bits 1 and 3 are outputs, other pins are inputs
    GPIO_PORTF_DR2R_R = 0x0A; // set drive strength to 2mA (not needed since default configuration -- for clarity)
    GPIO_PORTF_DEN_R = 0x1A;  // enable LEDs and pushbuttons
    GPIO_PORTF_PUR_R = 0x10;  // enable internal pull-up for push button

    // Configure UART0 pins
    SYSCTL_RCGCUART_R |= SYSCTL_RCGCUART_R0;         // turn-on UART0, leave other uarts in same status
    GPIO_PORTA_DEN_R |= 3;                           // default, added for clarity
    GPIO_PORTA_AFSEL_R |= 3;                         // default, added for clarity
    GPIO_PORTA_PCTL_R = GPIO_PCTL_PA1_U0TX | GPIO_PCTL_PA0_U0RX;

    // Configure UART0 to 115200 baud, 8N1 format (must be 3 clocks from clock enable and config writes)
    UART0_CTL_R = 0;                                 // turn-off UART0 to allow safe programming
    UART0_CC_R = UART_CC_CS_SYSCLK;                  // use system clock (40 MHz)
    UART0_IBRD_R = 21;                               // r = 40 MHz / (Nx115.2kHz), set floor(r)=21, where N=16
    UART0_FBRD_R = 45;                               // round(fract(r)*64)=45
    UART0_LCRH_R = UART_LCRH_WLEN_8 | UART_LCRH_FEN; // configure for 8N1 w/ 16-level FIFO
    UART0_CTL_R = UART_CTL_TXE | UART_CTL_RXE | UART_CTL_UARTEN; // enable TX, RX, and module


    // Configure UART3 pins
     SYSCTL_RCGCUART_R |= SYSCTL_RCGCUART_R3;         // turn-on UART3, leave other uarts in same status
     GPIO_PORTC_DEN_R |= 0x0C0;
     GPIO_PORTC_AFSEL_R |= 0x0C0;
     GPIO_PORTC_PCTL_R = GPIO_PCTL_PC7_U3TX | GPIO_PCTL_PC6_U3RX;

     // Configure UART3 to 115200 baud, 8N1 format (must be 3 clocks from clock enable and config writes)
     UART3_CTL_R = 0;                                 // turn-off UART3 to allow safe programming
     UART3_CC_R = UART_CC_CS_SYSCLK;                  // use system clock (40 MHz)
     UART3_IBRD_R = 21;                               // r = 40 MHz / (Nx115.2kHz), set floor(r)=21, where N=16
     UART3_FBRD_R = 45;                               // round(fract(r)*64)=45
     UART3_LCRH_R = UART_LCRH_WLEN_8 | UART_LCRH_FEN; // configure for 8N1 w/ 16-level FIFO
     UART3_CTL_R = UART_CTL_TXE | UART_CTL_RXE | UART_CTL_UARTEN; // enable TX, RX, and module
}

// Blocking function that writes a serial character when the UART buffer is not full
void putcUart0(char c)
{
    while (UART0_FR_R & UART_FR_TXFF);
    UART0_DR_R = c;
}

// Blocking function that writes a string when the UART buffer is not full
void putsUart0(char* str)
{
    uint8_t i;
    for (i = 0; i < strlen(str); i++)
      putcUart0(str[i]);
}

// Blocking function that returns with serial data once the buffer is not empty
char getcUart0()
{
    while (UART0_FR_R & UART_FR_RXFE);
    return UART0_DR_R & 0xFF;
}

//-------------------------------------------------------------------------------------------------

void putcUart3(char c)
{
    while (UART3_FR_R & UART_FR_TXFF);
    UART3_DR_R = c;
}

// Blocking function that writes a string when the UART buffer is not full
void putsUart3(char* str)
{
    uint8_t i;
    for (i = 0; i < strlen(str); i++)
      putcUart3(str[i]);
}

// Blocking function that returns with serial data once the buffer is not empty
char getcUart3()
{
    while (UART3_FR_R & UART_FR_RXFE);
    return UART3_DR_R & 0xFF;
}


//-----------------------------------------------------------------------------
// Main
//-----------------------------------------------------------------------------

int main(void)
{
    // Initialize hardware
    initHw();

    // Display greeting
    putsUart0("Serial Example\r\n");

    putcUart3('A');

    while(1)
    {
        char c = getcUart0();
        GREEN_LED ^= 1;
        if (c == '1')
            RED_LED = 1;
        if (c == '0')
            RED_LED = 0;
    }
}