msb430-uart1.c

/*
Copyright 2007, Freie Universitaet Berlin. All rights reserved.

These sources were developed at the Freie Universität Berlin, Computer
Systems and Telematics group.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.

- 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.
 
- Neither the name of Freie Universitaet Berlin (FUB) 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 FUB and the contributors on an "as is"
basis, without any representations or warranties of any kind, express
or implied including, but not limited to, representations or
warranties of non-infringement, merchantability or fitness for a
particular purpose. In no event shall FUB 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.

This implementation was developed by the CST group at the FUB.

For documentation and questions please use the web site
http://scatterweb.mi.fu-berlin.de and the mailinglist
scatterweb@lists.spline.inf.fu-berlin.de (subscription via the Website).
Berlin, 2007
*/

/**
 * @file                ScatterWeb.Uart.c
 * @addtogroup  interfaces
 * @brief               UART interface
 * @author              Michael Baar    <baar@inf.fu-berlin.de>
 *
 * UART switch for RS232 and SPI protocols on UART1 written for
 * ScatterWeb MSB boards. Compatible to ScatterWeb EOS,
 * ScatterWeb Bootload and Contiki.
 */

#include "contiki.h"
#include <string.h>
#include "dev/msb430-uart1.h"
#include "dev/lpm.h"

#ifndef U1ME
#define U1ME    ME2
#endif

volatile unsigned char uart_mode = UART_MODE_RESET;
volatile unsigned char uart_lockcnt = 0;
volatile uint8_t uart_edge = 0;

static unsigned char uart_speed_br0[UART_NUM_MODES];
static unsigned char uart_speed_br1[UART_NUM_MODES];
static unsigned char uart_speed_bmn[UART_NUM_MODES];
static uart_handler_t uart_handler[UART_NUM_MODES] = {NULL, NULL};

/*---------------------------------------------------------------------------*/
static void
uart_configure(unsigned mode)
{
  _DINT();              /* disable interrupts */

  UART_WAIT_TXDONE();   /* wait till all buffered data has been transmitted */

  if(mode == UART_MODE_RS232) {
    P5OUT |= 0x01;                                                      
    /* unselect SPI */
    P3SEL |= 0xC0;                                                      
    /* select rs232 */
    UCTL1 = SWRST | CHAR;               /* 8-bit character */
    UTCTL1 |= SSEL1;                    /* UCLK = MCLK */
    /* activate */
    U1ME |= UTXE1 | URXE1;              /* Enable USART1 TXD/RXD                 */
  } else if(mode == UART_MODE_SPI) {
    P3SEL &= ~0xC0;                     /* unselect RS232 */
    // to SPI mode
    UCTL1 = SWRST | CHAR | SYNC | MM;   /* 8-bit SPI Master */
    /*
     * SMCLK, 3-pin mode, clock idle low, data valid on
     * rising edge, UCLK delayed
     */
    UTCTL1 |= CKPH | SSEL1 | SSEL0 | STC;       /* activate */
    U1ME |= USPIE1;                             /* Enable USART1 SPI */
  }

  /* restore speed settings */
  UBR01  = uart_speed_br0[mode];        /* set baudrate */
  UBR11  = uart_speed_br1[mode];                        
  UMCTL1 = uart_speed_bmn[mode];        /* set modulation */

  UCTL1 &= ~SWRST;                      /* clear reset flag */
  _EINT();                              /* enable interrupts */
}
/*---------------------------------------------------------------------------*/
void
uart_set_speed(unsigned mode, unsigned ubr0,
                unsigned ubr1, unsigned umctl)
{
  /* store the setting */
  uart_speed_br0[mode] = ubr0;  /* baudrate */
  uart_speed_br1[mode] = ubr1;  /* baudrate */
  uart_speed_bmn[mode] = umctl; /* modulation */

  /* reconfigure, if mode active */
  if(uart_mode == mode) {
    uart_configure(mode);
  }
}
/*---------------------------------------------------------------------------*/
void
uart_set_handler(unsigned mode, uart_handler_t handler)
{
  /* store the setting */
  uart_handler[mode] = handler;
  if(mode == uart_mode) {
    if(handler == NULL) {
      IE2 &= ~URXIE1;                   /* Disable USART1 RX interrupt */
    } else {
      IE2 |= URXIE1;                    /* Enable USART1 RX interrupt */
    }
  }
}
/*---------------------------------------------------------------------------*/
int
uart_lock(unsigned mode)
{
  /* already locked? */
  if(uart_mode != mode && uart_lockcnt > 0) {
    return 0;
  }

  /* increase lock count */
  uart_lockcnt++;
  /* switch mode (if neccessary) */
  uart_set_mode(mode);
  return 1;
}
/*---------------------------------------------------------------------------*/
int
uart_lock_wait(unsigned mode)
{
  while(UART_WAIT_LOCK(mode)) {
    _NOP();
  }
  return uart_lock(mode);
}
/*---------------------------------------------------------------------------*/
int
uart_unlock(unsigned mode)
{
  if((uart_lockcnt == 0) || (mode != uart_mode)) {
    uart_lockcnt = 0;
    uart_set_mode(UART_MODE_DEFAULT);
    return 0;
  }

  /* decrement lock */
  if(uart_lockcnt > 0) {
    uart_lockcnt--;
    /* if no more locks, switch back to default mode */
    if(uart_lockcnt == 0) {
      uart_set_mode(UART_MODE_DEFAULT);
    }
    return 1;
  }
  return 0;
}
/*---------------------------------------------------------------------------*/
void
uart_set_mode(unsigned mode)
{
  /* do nothing if the mode is already set */
  if(mode == uart_mode) {
    return;
  }

  IE2 &= ~(URXIE1 | UTXIE1);            /* disable irq */
  uart_configure(mode);                 /* configure uart parameters */
  uart_mode = mode;
        
  if(uart_handler[mode] != NULL) {
    IE2 |= URXIE1;                      /* Enable USART1 RX interrupt */
  }
}
/*---------------------------------------------------------------------------*/
int
uart_get_mode(void)
{
  return uart_mode;
}
/*---------------------------------------------------------------------------*/
interrupt(UART1RX_VECTOR)
uart_rx(void)
{
  uart_handler_t handler = uart_handler[uart_mode];
  int c;
        
  if(!(IFG2 & URXIFG1)) {
    /* If rising edge is detected, toggle & return */
    uart_edge = 1;
    U1TCTL &= ~URXSE;
    U1TCTL |= URXSE;
    _BIC_SR_IRQ(LPM3_bits);
    return;
  }
  uart_edge = 0;
  if(!(URCTL1 & RXERR)) {
    c = UART_RX;
    if(handler(c)) {
      _BIC_SR_IRQ(LPM3_bits);
    }
  } else {
    /* read out the char to clear the interrupt flags. */
    c = UART_RX;
  }
}