/* p4_2.c UART0 Receive

 * Receiving any key from terminal emulator (TeraTerm) of the
 * host PC to the UART0 on Freescale FRDM-KL25Z board.
 * UART0 is connected to openSDA debug agent and has
 * a virtual connection to the host PC COM port.
 * Launch TeraTerm on a PC and hit any key.
 * The LED program from P2_7 of Chapter 2 is used to turn
 * on the tri-color LEDs according to the key received.
 *
 * By default in SystemInit(), FLL clock output is 41.94 MHz.
 * Setting BDH=0, BDL=0x17, and OSR=0x0F yields 115200 Baud.
 */

#include <MKL25Z4.H>

void UART0_init(void);
void delayMs(int n);
void LED_init(void);
void LED_set(int value);

int main (void) {
    char c;

    UART0_init();
    LED_init();
    
    while (1) {
        while(!(UART0->S1 & 0x20)) {
        }   /* wait for receive buffer full */
        c = UART0->D; /* read the char received */
        LED_set(c);
    }
}

/* initialize UART0 to receive at 115200 Baud */
void UART0_init(void) {
    SIM->SCGC4 |= 0x0400;   /* enable clock for UART0 */
    SIM->SOPT2 |= 0x04000000;    /* use FLL output for UART Baud rate generator */
    UART0->C2 = 0;          /* turn off UART0 while changing configurations */
    UART0->BDH = 0x00;
    UART0->BDL = 0x17;      /* 115200 Baud */
    UART0->C4 = 0x0F;       /* Over Sampling Ratio 16 */
    UART0->C1 = 0x00;       /* 8-bit data */
    UART0->C2 = 0x04;       /* enable receive */

    SIM->SCGC5 |= 0x0200;   /* enable clock for PORTA */
    PORTA->PCR[1] = 0x0200; /* make PTA1 UART0_Rx pin */
}

/* initialize all three LEDs on the FRDM board */
void LED_init(void)
{
    SIM->SCGC5 |= 0x400;        /* enable clock to Port B */
    SIM->SCGC5 |= 0x1000;       /* enable clock to Port D */
    PORTB->PCR[18] = 0x100;     /* make PTB18 pin as GPIO */
    PTB->PDDR |= 0x40000;       /* make PTB18 as output pin */
    PTB->PSOR = 0x40000;        /* turn off red LED */
    PORTB->PCR[19] = 0x100;     /* make PTB19 pin as GPIO */
    PTB->PDDR |= 0x80000;       /* make PTB19 as output pin */
    PTB->PSOR = 0x80000;        /* turn off green LED */
    PORTD->PCR[1] = 0x100;      /* make PTD1 pin as GPIO */
    PTD->PDDR |= 0x02;          /* make PTD1 as output pin */
    PTD->PSOR = 0x02;           /* turn off blue LED */
}

/* turn on or off the LEDs according to bit 2-0 of the value */
void LED_set(int value)
{
    if (value & 1)    /* use bit 0 of value to control red LED */
        PTB->PCOR = 0x40000;    /* turn on red LED */
    else
        PTB->PSOR = 0x40000;    /* turn off red LED */
    
    if (value & 2)    /* use bit 1 of value to control green LED */
        PTB->PCOR = 0x80000;    /* turn on green LED */
    else
        PTB->PSOR = 0x80000;    /* turn off green LED */
    
    if (value & 4)    /* use bit 2 of value to control blue LED */
        PTD->PCOR = 0x02;       /* turn on blue LED */
    else
        PTD->PSOR = 0x02;       /* turn off blue LED */
}