USRT

#include

#ifndef RXB8
#define RXB8 1
#endif

#ifndef TXB8
#define TXB8 0
#endif

#ifndef UPE
#define UPE 2
#endif

#ifndef DOR
#define DOR 3
#endif

#ifndef FE
#define FE 4
#endif

#ifndef UDRE
#define UDRE 5
#endif

#ifndef RXC
#define RXC 7
#endif

#define FRAMING_ERROR (1< #define PARITY_ERROR (1< #define DATA_OVERRUN (1< #define DATA_REGISTER_EMPTY (1< #define RX_COMPLETE (1<

// USART Receiver buffer
#define RX_BUFFER_SIZE 50
char rx_buffer[RX_BUFFER_SIZE];

#if RX_BUFFER_SIZE <= 256
unsigned char rx_wr_index,rx_rd_index,rx_counter;
#else
unsigned int rx_wr_index,rx_rd_index,rx_counter;
#endif

// This flag is set on USART Receiver buffer overflow
bit rx_buffer_overflow;

// USART Receiver interrupt service routine
interrupt [USART_RXC] void usart_rx_isr(void)
{
char status,data;
status=UCSRA;
data=UDR;
if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
   {
   rx_buffer[rx_wr_index++]=data;
#if RX_BUFFER_SIZE == 256
   // special case for receiver buffer size=256
   if (++rx_counter == 0)
      {
#else
   if (rx_wr_index == RX_BUFFER_SIZE) rx_wr_index=0;
   if (++rx_counter == RX_BUFFER_SIZE)
      {
      rx_counter=0;
#endif
      rx_buffer_overflow=1;
      }
   }
}

#ifndef _DEBUG_TERMINAL_IO_
// Get a character from the USART Receiver buffer
#define _ALTERNATE_GETCHAR_
#pragma used+
char getchar(void)
{
char data;
while (rx_counter==0);
data=rx_buffer[rx_rd_index++];
#if RX_BUFFER_SIZE != 256
if (rx_rd_index == RX_BUFFER_SIZE) rx_rd_index=0;
#endif
#asm("cli")
--rx_counter;
#asm("sei")
return data;
}
#pragma used-
#endif

// USART Transmitter buffer
#define TX_BUFFER_SIZE 50
char tx_buffer[TX_BUFFER_SIZE];

#if TX_BUFFER_SIZE <= 256
unsigned char tx_wr_index,tx_rd_index,tx_counter;
#else
unsigned int tx_wr_index,tx_rd_index,tx_counter;
#endif

// USART Transmitter interrupt service routine
interrupt [USART_TXC] void usart_tx_isr(void)
{
if (tx_counter)
   {
   --tx_counter;
   UDR=tx_buffer[tx_rd_index++];
#if TX_BUFFER_SIZE != 256
   if (tx_rd_index == TX_BUFFER_SIZE) tx_rd_index=0;
#endif
   }
}

#ifndef _DEBUG_TERMINAL_IO_
// Write a character to the USART Transmitter buffer
#define _ALTERNATE_PUTCHAR_
#pragma used+
void putchar(char c)
{
while (tx_counter == TX_BUFFER_SIZE);
#asm("cli")
if (tx_counter || ((UCSRA & DATA_REGISTER_EMPTY)==0))
   {
   tx_buffer[tx_wr_index++]=c;
#if TX_BUFFER_SIZE != 256
   if (tx_wr_index == TX_BUFFER_SIZE) tx_wr_index=0;
#endif
   ++tx_counter;
   }
else
   UDR=c;
#asm("sei")
}
#pragma used-
#endif
// USART initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART Receiver: On
// USART Transmitter: On
// USART Mode: Asynchronous
// USART Baud Rate: 9600
void USART_Init(void)
{
    UCSRA=0x00;
    UCSRB=0xD8;
    UCSRC=0x86;
    UBRRH=0x00;
    UBRRL=0x33;
}