spi.c

/*
 * Copyright (c) 2006, 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. 
 *
 * @(#)$Id: spi.c,v 1.1 2006/06/17 22:41:21 adamdunkels Exp $
 */

#include <io.h>

#include "contiki-conf.h"

/*
 * On the Tmote sky access to I2C/SPI/UART0 must always be
 * exclusive. Set spi_busy so that interrupt handlers can check if
 * they are allowed to use the bus or not. Only the CC2420 radio needs
 * this in practice.
 * 
 */
unsigned char spi_busy = 0;

/*
 * Initialize SPI bus.
 */
void
spi_init(void)
{
  static unsigned char spi_inited = 0;

  if (spi_inited)
    return;

  /* Initalize ports for communication with SPI units. */

  U0CTL  = CHAR + SYNC + MM + SWRST; /* SW  reset,8-bit transfer, SPI master */
  U0TCTL = CKPH + SSEL1 + STC;  /* Data on Rising Edge, SMCLK, 3-wire. */

  U0BR0  = 0x02;                /* SPICLK set baud. */
  U0BR1  = 0;  /* Dont need baud rate control register 2 - clear it */
  U0MCTL = 0;                   /* Dont need modulation control. */

  P3SEL |= BV(SCK) | BV(MOSI) | BV(MISO); /* Select Peripheral functionality */
  P3DIR |= BV(SCK) | BV(MISO);  /* Configure as outputs(SIMO,CLK). */

  ME1   |= USPIE0;         /* Module enable ME1 --> U0ME? xxx/bg */
  U0CTL &= ~SWRST;              /* Remove RESET */
}