/* Name: sw-uart.c * Project: AVR USB driver for CDC interface on Low-Speed USB * Author: Osamu Tamura * Creation Date: 2006-06-22 * Tabsize: 4 * Copyright: (c) 2006 by Recursion Co., Ltd. * License: Proprietary, free under certain conditions. See Documentation. *
 *  2006-07-10 software-UART interrupt handling time reduced.
 *//*General Description:*/#include <avr/io.h>#include <avr/interrupt.h>#include "oddebug.h"#include "uart.h"#if !UART_CFG_HAVE_USART/* UART buffer */uchar    urptr, uwptr, irptr, iwptr;uchar    rx_buf[RX_SIZE], tx_buf[TX_SIZE];


void uartInit(ulong baudrate, uchar parity, uchar stopbits, uchar databits){
    PRR     = (1<<PRUSI)|(1<<PRADC);
    ACSR    = (1<<ACD);

#if UART_CFG_INVERT
    UART_CFG_PORT   &= ~(1<<UART_CFG_TXD);#else
    UART_CFG_PORT   |= (1<<UART_CFG_TXD);#endif
    UART_DDR    |= (1<<UART_CFG_TXD);
    UART_DDR    &= ~(1<<UART_CFG_RXD);
    
    GIMSK    &= ~(1<<PCIE);    TCCR0A   = 0;    TCCR0B   = 0;    TCCR1    = 0;
    OCR0A    =    OCR1A    = (F_CPU/64L) / (unsigned int)baudrate - 1;
    OCR1C    = 0;    DT1A     = -(OCR1A/3);        /* 1.5 sample bit */
    TCCR0A   = 2;                 /* CTC */    DT1B     = 1;    EEARL    = 0;    TIMSK    = (1<<OCIE1A)|(1<<OCIE0A);    PCMSK    = 1<<UART_CFG_RXD;   /*  PCINTn  */    GIMSK    |= (1<<PCIE);}void uartPoll(void){

    /* transmit data    */
    if( TCCR0B==0 && irptr!=uwptr ) {        EEARL    = 10;      /* tx_bit counter   */        OCR0B    = tx_buf[irptr];        irptr    = (irptr+1) & TX_MASK;        TCNT0    = 0;        cli();#if UART_CFG_INVERT
        UART_CFG_PORT   |= (1<<UART_CFG_TXD);       /* start bit */#else
        UART_CFG_PORT   &= ~(1<<UART_CFG_TXD);      /* start bit */#endif
        TCCR0B   = 3;       /* start timer0: 1/64 clk */        sei();    }
    /* receive data     */
    if( DT1B==0 ) {         /* rx_data ready?   */
        DT1B     = 1;        uartRxBufAppend( EEDR );    }}uchar uartRxIsBusy(void){    return OCR1C;}#endif      /* UART_CFG_HAVE_USART */