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uart2.c

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/*! \file uart2.c \brief Dual UART driver with buffer support. */
//*****************************************************************************
//
// File Name    : 'uart2.c'
// Title        : Dual UART driver with buffer support
// Author       : Pascal Stang - Copyright (C) 2000-2003
// Created      : 11/20/2000
// Revised      : 06/09/2003
// Version      : 1.0
// Target MCU   : ATMEL AVR Series
// Editor Tabs  : 4
//
// Description  : This is a UART driver for AVR-series processors with two
//      hardware UARTs such as the mega161 and mega128 
//
// 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 <avr/signal.h>

#include "buffer.h"
#include "uart2.h"

// UART global variables
// flag variables
volatile u08   uartReadyTx[2];
volatile u08   uartBufferedTx[2];
// receive and transmit buffers
cBuffer uartRxBuffer[2];
cBuffer uartTxBuffer[2];
unsigned short uartRxOverflow[2];
#ifndef UART_BUFFERS_EXTERNAL_RAM
    // using internal ram,
    // automatically allocate space in ram for each buffer
    static char uart0RxData[UART0_RX_BUFFER_SIZE];
    static char uart0TxData[UART0_TX_BUFFER_SIZE];
    static char uart1RxData[UART1_RX_BUFFER_SIZE];
    static char uart1TxData[UART1_TX_BUFFER_SIZE];
#endif

typedef void (*voidFuncPtru08)(unsigned char);
volatile static voidFuncPtru08 UartRxFunc[2];

void uartInit(void)
{
    // initialize the buffers
    uartInitBuffers();
    // initialize user receive handlers
    UartRxFunc[0] = 0;
    UartRxFunc[1] = 0;

    // enable RxD/TxD and interrupts
    #ifdef UCR
        // this line for AT90S8515,8535,ATmega103,etc
        outb(UCR, BV(RXCIE)|BV(TXCIE)|BV(RXEN)|BV(TXEN));
    #endif
    #ifdef UCSRB
        // this line for the Mega163
        outb(UCSRB, BV(RXCIE)|BV(TXCIE)|BV(RXEN)|BV(TXEN));
    #endif
    #ifdef UCSR0B
        // this line for the Mega161/128
        outb(UCSR0B, BV(RXCIE)|BV(TXCIE)|BV(RXEN)|BV(TXEN));
        outb(UCSR1B, BV(RXCIE)|BV(TXCIE)|BV(RXEN)|BV(TXEN));
    #endif

    // set default baud rate
    uartSetBaudRate(0, UART0_DEFAULT_BAUD_RATE); 
    uartSetBaudRate(1, UART1_DEFAULT_BAUD_RATE);
    // initialize states
    uartReadyTx[0] = TRUE;
    uartReadyTx[1] = TRUE;
    uartBufferedTx[0] = FALSE;
    uartBufferedTx[1] = FALSE;
    // clear overflow count
    uartRxOverflow[0] = 0;
    uartRxOverflow[1] = 0;
    // enable interrupts
    sei();
}

void uartInitBuffers(void)
{
    #ifndef UART_BUFFERS_EXTERNAL_RAM
        // initialize the UART0 buffers
        bufferInit(&uartRxBuffer[0], uart0RxData, UART0_RX_BUFFER_SIZE);
        bufferInit(&uartTxBuffer[0], uart0TxData, UART0_TX_BUFFER_SIZE);
        // initialize the UART1 buffers
        bufferInit(&uartRxBuffer[1], uart1RxData, UART1_RX_BUFFER_SIZE);
        bufferInit(&uartTxBuffer[1], uart1TxData, UART1_TX_BUFFER_SIZE);
    #else
        // initialize the UART0 buffers
        bufferInit(&uartRxBuffer[0], (u08*) UART0_RX_BUFFER_ADDR, UART0_RX_BUFFER_SIZE);
        bufferInit(&uartTxBuffer[0], (u08*) UART0_TX_BUFFER_ADDR, UART0_TX_BUFFER_SIZE);
        // initialize the UART1 buffers
        bufferInit(&uartRxBuffer[1], (u08*) UART1_RX_BUFFER_ADDR, UART1_RX_BUFFER_SIZE);
        bufferInit(&uartTxBuffer[1], (u08*) UART1_TX_BUFFER_ADDR, UART1_TX_BUFFER_SIZE);
    #endif
}

void uartSetRxHandler(u08 nUart, void (*rx_func)(unsigned char c))
{
    // make sure the uart number is within bounds
    if(nUart < 2)
    {
        // set the receive interrupt to run the supplied user function
        UartRxFunc[nUart] = rx_func;
    }
}

void uartSetBaudRate(u08 nUart, u32 baudrate)
{
    // calculate division factor for requested baud rate, and set it
    u08 baudrateDiv;
    baudrateDiv = (u08)((F_CPU+(baudrate*8L))/(baudrate*16L)-1);
    if(nUart)
        outb(UBRR1L, baudrateDiv);
    else
        outb(UBRR0L, baudrateDiv);
}

cBuffer* uartGetRxBuffer(u08 nUart)
{
    // return rx buffer pointer
    return &uartRxBuffer[nUart];
}

cBuffer* uartGetTxBuffer(u08 nUart)
{
    // return tx buffer pointer
    return &uartTxBuffer[nUart];
}

void uartSendByte(u08 nUart, u08 txData)
{
    // wait for the transmitter to be ready
    while(!uartReadyTx[nUart]);
    // send byte
    if(nUart)
        outb(UDR1, txData);
    else
        outb(UDR0, txData);
    // set ready state to FALSE
    uartReadyTx[nUart] = FALSE;
}

void uart0SendByte(u08 data)
{
    // send byte on UART0
    uartSendByte(0, data);
}

void uart1SendByte(u08 data)
{
    // send byte on UART1
    uartSendByte(1, data);
}

u08 uartReceiveByte(u08 nUart, u08* rxData)
{
    // make sure we have a receive buffer
    if(uartRxBuffer[nUart].size)
    {
        // make sure we have data
        if(uartRxBuffer[nUart].datalength)
        {
            // get byte from beginning of buffer
            *rxData = bufferGetFromFront(&uartRxBuffer[nUart]);
            return TRUE;
        }
        else
            return FALSE;           // no data
    }
    else
        return FALSE;               // no buffer
}

void uartFlushReceiveBuffer(u08 nUart)
{
    // flush all data from receive buffer
    bufferFlush(&uartRxBuffer[nUart]);
}

u08 uartReceiveBufferIsEmpty(u08 nUart)
{
    return (uartRxBuffer[nUart].datalength == 0);
}

void uartAddToTxBuffer(u08 nUart, u08 data)
{
    // add data byte to the end of the tx buffer
    bufferAddToEnd(&uartTxBuffer[nUart], data);
}

void uart0AddToTxBuffer(u08 data)
{
    uartAddToTxBuffer(0,data);
}

void uart1AddToTxBuffer(u08 data)
{
    uartAddToTxBuffer(1,data);
}

void uartSendTxBuffer(u08 nUart)
{
    // turn on buffered transmit
    uartBufferedTx[nUart] = TRUE;
    // send the first byte to get things going by interrupts
    uartSendByte(nUart, bufferGetFromFront(&uartTxBuffer[nUart]));
}

u08 uartSendBuffer(u08 nUart, 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[nUart].datalength + nBytes < uartTxBuffer[nUart].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[nUart], *buffer++);
        }

        // send the first byte to get things going by interrupts
        uartBufferedTx[nUart] = TRUE;
        uartSendByte(nUart, first);
        // return success
        return TRUE;
    }
    else
    {
        // return failure
        return FALSE;
    }
}

// UART Transmit Complete Interrupt Function
void uartTransmitService(u08 nUart)
{
    // check if buffered tx is enabled
    if(uartBufferedTx[nUart])
    {
        // check if there's data left in the buffer
        if(uartTxBuffer[nUart].datalength)
        {
            // send byte from top of buffer
            if(nUart)
                outb(UDR1,  bufferGetFromFront(&uartTxBuffer[1]) );
            else
                outb(UDR0,  bufferGetFromFront(&uartTxBuffer[0]) );
        }
        else
        {
            // no data left
            uartBufferedTx[nUart] = FALSE;
            // return to ready state
            uartReadyTx[nUart] = TRUE;
        }
    }
    else
    {
        // we're using single-byte tx mode
        // indicate transmit complete, back to ready
        uartReadyTx[nUart] = TRUE;
    }
}

// UART Receive Complete Interrupt Function
void uartReceiveService(u08 nUart)
{
    u08 c;
    // get received char
    if(nUart)
        c = inb(UDR1);
    else
        c = inb(UDR0);

    // if there's a user function to handle this receive event
    if(UartRxFunc[nUart])
    {
        // call it and pass the received data
        UartRxFunc[nUart](c);
    }
    else
    {
        // otherwise do default processing
        // put received char in buffer
        // check if there's space
        if( !bufferAddToEnd(&uartRxBuffer[nUart], c) )
        {
            // no space in buffer
            // count overflow
            uartRxOverflow[nUart]++;
        }
    }
}

UART_INTERRUPT_HANDLER(SIG_UART0_TRANS)      
{
    // service UART0 transmit interrupt
    uartTransmitService(0);
}

UART_INTERRUPT_HANDLER(SIG_UART1_TRANS)      
{
    // service UART1 transmit interrupt
    uartTransmitService(1);
}

UART_INTERRUPT_HANDLER(SIG_UART0_RECV)      
{
    // service UART0 receive interrupt
    uartReceiveService(0);
}

UART_INTERRUPT_HANDLER(SIG_UART1_RECV)      
{
    // service UART1 receive interrupt
    uartReceiveService(1);
}

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