#ifndef _UART_H_

#define _UART_H_

// Helpful defines

#define uart_buffer r_buffer

#define uart_ready r_ready

// RXC ISR variables

unsigned char r_index; // current string index

unsigned char r_buffer[16]; // input string

unsigned char r_ready; // flag for receive done

unsigned char r_char; // current character

// TX ISR variables

// Set up a circular buffer to output the strings to

#ifndef TRANSMIT_BUFFER_SIZE

#define TRANSMIT_BUFFER_SIZE 21

#endif

unsigned char t_index; // current string index

unsigned char t_end; // index of end

unsigned char t_buffer[TRANSMIT_BUFFER_SIZE]; //output string

unsigned char t_char; //current character

// Instruction length

#ifndef INST_LENGTH

#define INST_LENGTH 6

#endif

// XMIT output DDR

#ifndef XMIT_DDR

#define XMIT_DDR DDRD.4

#endif

// XMIT output port

#ifndef XMIT_OUT

#define XMIT_OUT PORTD.4

#endif

// UART receive byte ready interrupt

interrupt [USART_RXC] void uart_rec(void)

{

// Set the XMIT line to recieve

XMIT_OUT = 0;

// Read in a character

r_char=UDR;

// Add the character to the receive buffer

r_buffer[r_index++]=r_char;

// If we have received a full instruction

if (r_index == INST_LENGTH)

{

// Set the message ready flag

r_ready=1;

// Turn off the receive interrupt

UCSRB.7=0;

}

}

// UART data register empty interrupt

interrupt [USART_DRE] void uart_tx(void)

{

// Set the XMIT line to transmit

XMIT_OUT = 1;

// Read in a char from the buffer

t_char = t_buffer[t_index];

// Increase and mod the index, to make this a circular buffer

t_index = (t_index + 1) % TRANSMIT_BUFFER_SIZE;

// If we have reached the end of the string

if (t_index == t_end)

{

// Turn off the transmit interrupt

UCSRB.5 = 0;

}

// Otherwise write it to the UART

else UDR = t_char;

// Set the XMIT line back to receive

XMIT_OUT = 0;

}

// Function to setup the receive interrupt

void uart_gets_int(void)

{

// Reset the variables

r_ready=0;

r_index=0;

// Enable the receive ISR

UCSRB.7=1;

}

// Function to initialize the UART

void uart_init(unsigned char newBPS)

{

// Setup the UART registers

UCSRB = 0x18;

UBRRL = newBPS;

// Setup the XMIT line

XMIT_DDR = 1;

}

#endif