/*
 *uart.c VER1.0
 *This is a uart.c file of the UART Hardware demo using USCI on the MSP430G2553 microcontroller.
 *Set your baud rate in your terminal to 9600 8N1.
 *When using your TI MSP-430 LaunchPad you will need to cross the TXD and RXD jumpers.
 *
 *This program is free software: you can redistribute it and/or modify
 *it under the terms of the GNU General Public License as published by
 *the Free Software Foundation, either version 3 of the License, or
 *(at your option) any later version.

 *This program is distributed in the hope that it will be useful,
 *but WITHOUT ANY WARRANTY; without even the implied warranty of
 *MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *GNU General Public License for more details.
 *
 *You should have received a copy of the GNU General Public License
 *along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *Parker Dillmann
 *www.longhornengineer.com
*/

#include "msp430g2553.h"
#include "uart.h"

#define LED BIT0
#define RXD BIT1
#define TXD BIT2


volatile unsigned int tx_flag;			//Mailbox Flag for the tx_char.
volatile unsigned char tx_char;			//This char is the most current char to go into the UART

volatile unsigned int rx_flag;			//Mailbox Flag for the rx_char.
volatile unsigned char rx_char;			//This char is the most current char to come out of the UART

/*uart_init
* Sets up the UART interface via USCI
* INPUT: None
* RETURN: None
*/
void uart_init(void)
{
	P1SEL = RXD + TXD;					//Setup the I/O
	P1SEL2 = RXD + TXD;

    P1DIR |= LED; 						//P1.0 red LED. Toggle when char received.
    P1OUT |= LED; 						//LED off

	UCA0CTL1 |= UCSSEL_2; 				//SMCLK
										//8,000,000Hz, 9600Baud, UCBRx=52, UCBRSx=0, UCBRFx=1
	UCA0BR0 = 52;                  		//8MHz, OSC16, 9600
	UCA0BR1 = 0;                   	 	//((8MHz/9600)/16) = 52.08333
	UCA0MCTL = 0x10|UCOS16; 			//UCBRFx=1,UCBRSx=0, UCOS16=1
	UCA0CTL1 &= ~UCSWRST; 				//USCI state machine
	IE2 |= UCA0RXIE; 					//Enable USCI_A0 RX interrupt

	rx_flag = 0;						//Set rx_flag to 0
	tx_flag = 0;						//Set tx_flag to 0

	return;
}

/*uart_getc
* Get a char from the UART. Waits till it gets one
* INPUT: None
* RETURN: Char from UART
*/
unsigned char uart_getc()				//Waits for a valid char from the UART
{
	while (rx_flag == 0);		 		//Wait for rx_flag to be set
	rx_flag = 0;						//ACK rx_flag
    return rx_char;
}

/*uart_gets
* Get a string of known length from the UART. Strings terminate when enter is pressed or string buffer fills
* Will return when all the chars are received or a carriage return (\r) is received. Waits for the data.
* INPUT: Array pointer and length
* RETURN: None
*/
void uart_gets(char* Array, int length)
{
	unsigned int i = 0;

	while((i < length))					//Grab data till the array fills
	{
		Array[i] = uart_getc();
		if(Array[i] == '\r')				//If we receive a \r the master wants to end
		{
			for( ; i < length ; i++)		//fill the rest of the string with \0 nul. Overwrites the \r with \0
			{
				Array[i] = '\0';
			}
			break;
		}
		i++;
	}

    return;
}

/*uart_putc
* Sends a char to the UART. Will wait if the UART is busy
* INPUT: Char to send
* RETURN: None
*/
void uart_putc(unsigned char c)
{
	tx_char = c;						//Put the char into the tx_char
	IE2 |= UCA0TXIE; 					//Enable USCI_A0 TX interrupt
	while(tx_flag == 1);				//Have to wait for the TX buffer
	tx_flag = 1;						//Reset the tx_flag
	return;
}

/*uart_puts
* Sends a string to the UART. Will wait if the UART is busy
* INPUT: Pointer to String to send
* RETURN: None
*/
void uart_puts(char *str)				//Sends a String to the UART.
{
     while(*str) uart_putc(*str++);		//Advance though string till end
     return;
}

#pragma vector = USCIAB0TX_VECTOR		//UART TX USCI Interrupt
__interrupt void USCI0TX_ISR(void)
{
	UCA0TXBUF = tx_char;				//Copy char to the TX Buffer
	tx_flag = 0;						//ACK the tx_flag
	IE2 &= ~UCA0TXIE; 					//Turn off the interrupt to save CPU
}

#pragma vector = USCIAB0RX_VECTOR		//UART RX USCI Interrupt. This triggers when the USCI receives a char.
__interrupt void USCI0RX_ISR(void)
{
	rx_char = UCA0RXBUF;				//Copy from RX buffer, in doing so we ACK the interrupt as well
	rx_flag = 1;						//Set the rx_flag to 1

	P1OUT ^= LED;						//Notify that we received a char by toggling LED
}