spi.c

00001 /*
00002  * Copyright (c) 2006, Swedish Institute of Computer Science
00003  * All rights reserved. 
00004  *
00005  * Redistribution and use in source and binary forms, with or without 
00006  * modification, are permitted provided that the following conditions 
00007  * are met: 
00008  * 1. Redistributions of source code must retain the above copyright 
00009  *    notice, this list of conditions and the following disclaimer. 
00010  * 2. Redistributions in binary form must reproduce the above copyright 
00011  *    notice, this list of conditions and the following disclaimer in the 
00012  *    documentation and/or other materials provided with the distribution. 
00013  * 3. Neither the name of the Institute nor the names of its contributors 
00014  *    may be used to endorse or promote products derived from this software 
00015  *    without specific prior written permission. 
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
00018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
00020  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
00021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
00022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
00023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
00024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
00025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
00026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
00027  * SUCH DAMAGE. 
00028  *
00029  * @(#)$Id: spi.c,v 1.1 2006/06/17 22:41:21 adamdunkels Exp $
00030  */
00031 
00032 #include <io.h>
00033 
00034 #include "contiki-conf.h"
00035 
00036 /*
00037  * On the Tmote sky access to I2C/SPI/UART0 must always be
00038  * exclusive. Set spi_busy so that interrupt handlers can check if
00039  * they are allowed to use the bus or not. Only the CC2420 radio needs
00040  * this in practice.
00041  * 
00042  */
00043 unsigned char spi_busy = 0;
00044 
00045 /*
00046  * Initialize SPI bus.
00047  */
00048 void
00049 spi_init(void)
00050 {
00051   static unsigned char spi_inited = 0;
00052 
00053   if (spi_inited)
00054     return;
00055 
00056   /* Initalize ports for communication with SPI units. */
00057 
00058   U0CTL  = CHAR + SYNC + MM + SWRST; /* SW  reset,8-bit transfer, SPI master */
00059   U0TCTL = CKPH + SSEL1 + STC;  /* Data on Rising Edge, SMCLK, 3-wire. */
00060 
00061   U0BR0  = 0x02;                /* SPICLK set baud. */
00062   U0BR1  = 0;  /* Dont need baud rate control register 2 - clear it */
00063   U0MCTL = 0;                   /* Dont need modulation control. */
00064 
00065   P3SEL |= BV(SCK) | BV(MOSI) | BV(MISO); /* Select Peripheral functionality */
00066   P3DIR |= BV(SCK) | BV(MISO);  /* Configure as outputs(SIMO,CLK). */
00067 
00068   ME1   |= USPIE0;         /* Module enable ME1 --> U0ME? xxx/bg */
00069   U0CTL &= ~SWRST;              /* Remove RESET */
00070 }

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