/*! \file uart.c \brief UART driver with buffer support. */
// *****************************************************************************
//
// File Name : 'uart.c'
// Title : UART driver with buffer support
// Author : Pascal Stang - Copyright (C) 2000-2002
// Created : 11/22/2000
// Revised : 06/09/2003
// Version : 1.3
// Target MCU : ATMEL AVR Series
// Editor Tabs : 4
//
// This code is distributed under the GNU Public License
// which can be found at http://www.gnu.org/licenses/gpl.txt
//
// *****************************************************************************
#include <avr/io.h>
#include <avr/interrupt.h>
#include "buffer.h"
#include "uart.h"
// UART global variables
// flag variables
volatile u08 uartReadyTx; ///< uartReadyTx flag
volatile u08 uartBufferedTx; ///< uartBufferedTx flag
// receive and transmit buffers
cBuffer uartRxBuffer; ///< uart receive buffer
cBuffer uartTxBuffer; ///< uart transmit buffer
unsigned short uartRxOverflow; ///< receive overflow counter
#ifndef UART_BUFFERS_EXTERNAL_RAM
// using internal ram,
// automatically allocate space in ram for each buffer
static char uartRxData[UART_RX_BUFFER_SIZE];
static char uartTxData[UART_TX_BUFFER_SIZE];
#endif
typedef void (*voidFuncPtru08)(unsigned char);
volatile static voidFuncPtru08 UartRxFunc;
// enable and initialize the uart
void uartInit(void)
{
// initialize the buffers
uartInitBuffers();
// initialize user receive handler
UartRxFunc = 0;
// enable RxD/TxD and interrupts
outb(UCR, BV(RXCIE)|BV(TXCIE)|BV(RXEN)|BV(TXEN));
// set default baud rate
uartSetBaudRate(UART_DEFAULT_BAUD_RATE);
// initialize states
uartReadyTx = TRUE;
uartBufferedTx = FALSE;
// clear overflow count
uartRxOverflow = 0;
// enable interrupts
sei();
}
// create and initialize the uart transmit and receive buffers
void uartInitBuffers(void)
{
#ifndef UART_BUFFERS_EXTERNAL_RAM
// initialize the UART receive buffer
bufferInit(&uartRxBuffer, uartRxData, UART_RX_BUFFER_SIZE);
// initialize the UART transmit buffer
bufferInit(&uartTxBuffer, uartTxData, UART_TX_BUFFER_SIZE);
#else
// initialize the UART receive buffer
bufferInit(&uartRxBuffer, (u08*) UART_RX_BUFFER_ADDR, UART_RX_BUFFER_SIZE);
// initialize the UART transmit buffer
bufferInit(&uartTxBuffer, (u08*) UART_TX_BUFFER_ADDR, UART_TX_BUFFER_SIZE);
#endif
}
// redirects received data to a user function
void uartSetRxHandler(void (*rx_func)(unsigned char c))
{
// set the receive interrupt to run the supplied user function
UartRxFunc = rx_func;
}
// set the uart baud rate
void uartSetBaudRate(u32 baudrate)
{
// calculate division factor for requested baud rate, and set it
u16 bauddiv = ((F_CPU+(baudrate*8L))/(baudrate*16L)-1);
outb(UBRRL, bauddiv);
#ifdef UBRRH
outb(UBRRH, bauddiv>>8);
#endif
}
// returns the receive buffer structure
cBuffer* uartGetRxBuffer(void)
{
// return rx buffer pointer
return &uartRxBuffer;
}
// returns the transmit buffer structure
cBuffer* uartGetTxBuffer(void)
{
// return tx buffer pointer
return &uartTxBuffer;
}
// transmits a byte over the uart
void uartSendByte(u08 txData)
{
// wait for the transmitter to be ready
while(!uartReadyTx);
// send byte
outb(UDR, txData);
// set ready state to FALSE
uartReadyTx = FALSE;
}
// gets a single byte from the uart receive buffer (getchar-style)
int uartGetByte(void)
{
u08 c;
if(uartReceiveByte(&c))
return c;
else
return -1;
}
// gets a byte (if available) from the uart receive buffer
u08 uartReceiveByte(u08* rxData)
{
// make sure we have a receive buffer
if(uartRxBuffer.size)
{
// make sure we have data
if(uartRxBuffer.datalength)
{
// get byte from beginning of buffer
*rxData = bufferGetFromFront(&uartRxBuffer);
return TRUE;
}
else
{
// no data
return FALSE;
}
}
else
{
// no buffer
return FALSE;
}
}
// flush all data out of the receive buffer
void uartFlushReceiveBuffer(void)
{
// flush all data from receive buffer
//bufferFlush(&uartRxBuffer);
// same effect as above
uartRxBuffer.datalength = 0;
}
// return true if uart receive buffer is empty
u08 uartReceiveBufferIsEmpty(void)
{
if(uartRxBuffer.datalength == 0)
{
return TRUE;
}
else
{
return FALSE;
}
}
// add byte to end of uart Tx buffer
u08 uartAddToTxBuffer(u08 data)
{
// add data byte to the end of the tx buffer
return bufferAddToEnd(&uartTxBuffer, data);
}
// start transmission of the current uart Tx buffer contents
void uartSendTxBuffer(void)
{
// turn on buffered transmit
uartBufferedTx = TRUE;
// send the first byte to get things going by interrupts
uartSendByte(bufferGetFromFront(&uartTxBuffer));
}
/*
// transmit nBytes from buffer out the uart
u08 uartSendBuffer(char *buffer, u16 nBytes)
{
register u08 first;
register u16 i;
// check if there's space (and that we have any bytes to send at all)
if((uartTxBuffer.datalength + nBytes < uartTxBuffer.size) && nBytes)
{
// grab first character
first = *buffer++;
// copy user buffer to uart transmit buffer
for(i = 0; i < nBytes-1; i++)
{
// put data bytes at end of buffer
bufferAddToEnd(&uartTxBuffer, *buffer++);
}
// send the first byte to get things going by interrupts
uartBufferedTx = TRUE;
uartSendByte(first);
// return success
return TRUE;
}
else
{
// return failure
return FALSE;
}
}
*/
// UART Transmit Complete Interrupt Handler
UART_INTERRUPT_HANDLER(SIG_UART_TRANS)
{
// check if buffered tx is enabled
if(uartBufferedTx)
{
// check if there's data left in the buffer
if(uartTxBuffer.datalength)
{
// send byte from top of buffer
outb(UDR, bufferGetFromFront(&uartTxBuffer));
}
else
{
// no data left
uartBufferedTx = FALSE;
// return to ready state
uartReadyTx = TRUE;
}
}
else
{
// we're using single-byte tx mode
// indicate transmit complete, back to ready
uartReadyTx = TRUE;
}
}
// UART Receive Complete Interrupt Handler
UART_INTERRUPT_HANDLER(SIG_UART_RECV)
{
u08 c;
// get received char
c = inb(UDR);
// if there's a user function to handle this receive event
if(UartRxFunc)
{
// call it and pass the received data
UartRxFunc(c);
}
else
{
// otherwise do default processing
// put received char in buffer
// check if there's space
if( !bufferAddToEnd(&uartRxBuffer, c) )
{
// no space in buffer
// count overflow
uartRxOverflow++;
}
}
}
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