Contiki 2.5
spi.c
1 /*
2  * Copyright (c) 2006, Swedish Institute of Computer Science
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the Institute nor the names of its contributors
14  * may be used to endorse or promote products derived from this software
15  * without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  * @(#)$Id: spi.c,v 1.1 2006/06/17 22:41:21 adamdunkels Exp $
30  */
31 
32 #include "contiki-conf.h"
33 
34 /*
35  * On the Tmote sky access to I2C/SPI/UART0 must always be
36  * exclusive. Set spi_busy so that interrupt handlers can check if
37  * they are allowed to use the bus or not. Only the CC2420 radio needs
38  * this in practice.
39  *
40  */
41 unsigned char spi_busy = 0;
42 
43 /*
44  * Initialize SPI bus.
45  */
46 void
47 spi_init(void)
48 {
49  static unsigned char spi_inited = 0;
50 
51  if (spi_inited)
52  return;
53 
54  /* Initalize ports for communication with SPI units. */
55 
56  U0CTL = CHAR + SYNC + MM + SWRST; /* SW reset,8-bit transfer, SPI master */
57  U0TCTL = CKPH + SSEL1 + STC; /* Data on Rising Edge, SMCLK, 3-wire. */
58 
59  U0BR0 = 0x02; /* SPICLK set baud. */
60  U0BR1 = 0; /* Dont need baud rate control register 2 - clear it */
61  U0MCTL = 0; /* Dont need modulation control. */
62 
63  P3SEL |= BV(SCK) | BV(MOSI) | BV(MISO); /* Select Peripheral functionality */
64  P3DIR |= BV(SCK) | BV(MISO); /* Configure as outputs(SIMO,CLK). */
65 
66  ME1 |= USPIE0; /* Module enable ME1 --> U0ME? xxx/bg */
67  U0CTL &= ~SWRST; /* Remove RESET */
68 }