uart0.c

/*
 * Copyright (c) 2011, Swedish Institute of Computer Science
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
/*
 * Yet another machine dependent MSP430X UART0 code.
 * IF2, etc. can not be used here... need to abstract to some macros
 * later.
 */
 
#include "contiki.h"
#include <stdlib.h>
#include "dev/uart0.h"
#include "dev/watchdog.h"
#include "isr_compat.h"
 
static int (*uart0_input_handler)(unsigned char c);
 
static volatile uint8_t transmitting;
 
/*---------------------------------------------------------------------------*/
uint8_t
uart0_active(void)
{
  return (UCA0STAT & UCBUSY) | transmitting;
}
/*---------------------------------------------------------------------------*/
void
uart0_set_input(int (*input)(unsigned char c))
{
  uart0_input_handler = input;
}
/*---------------------------------------------------------------------------*/
void
uart0_writeb(unsigned char c)
{
  watchdog_periodic();
  /* Loop until the transmission buffer is available. */
  while((UCA0STAT & UCBUSY));
 
  /* Transmit the data. */
  UCA0TXBUF = c;
}
/*---------------------------------------------------------------------------*/
/**
 * Initalize the RS232 port.
 *
 */
void
uart0_init(unsigned long ubr)
{
  /* RS232 */
  UCA0CTL1 |= UCSWRST;            /* Hold peripheral in reset state */
  UCA0CTL1 |= UCSSEL_2;           /* CLK = SMCLK */
 
  ubr = (MSP430_CPU_SPEED / ubr);
  UCA0BR0 = ubr & 0xff;
  UCA0BR1 = (ubr >> 8) & 0xff;
  UCA0MCTL = UCBRS_3;             /* Modulation UCBRSx = 3 */
  P3DIR &= ~0x20;                 /* P3.5 = USCI_A0 RXD as input */
  P3DIR |= 0x10;                  /* P3.4 = USCI_A0 TXD as output */
  P3SEL |= 0x30;                  /* P3.4,5 = USCI_A0 TXD/RXD */
 
  /*UCA0CTL1 &= ~UCSWRST;*/       /* Initialize USCI state machine */
 
  transmitting = 0;
 
  /* XXX Clear pending interrupts before enable */
  UCA0IE &= ~UCRXIFG;
  UCA0IE &= ~UCTXIFG;
 
  UCA0CTL1 &= ~UCSWRST;                   /* Initialize USCI state machine **before** enabling interrupts */
  UCA0IE |= UCRXIE;                        /* Enable UCA0 RX interrupt */
}
/*---------------------------------------------------------------------------*/
ISR(USCI_A0, uart0_rx_interrupt)
{
  uint8_t c;
 
  if(UCA0IV == 2) {
    if(UCA0STAT & UCRXERR) {
      c = UCA0RXBUF;   /* Clear error flags by forcing a dummy read. */
    } else {
      c = UCA0RXBUF;
      if(uart0_input_handler != NULL) {
        if(uart0_input_handler(c)) {
          LPM4_EXIT;
        }
      }
    }
  }
}
/*---------------------------------------------------------------------------*/