contiki/dev/ds2411/ds2411.c

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/*
* Copyright (c) 2005, 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.
*
* This file is part of the Contiki operating system.
*
*/
/*
* Device driver for the Dallas Semiconductor DS2411 chip. Heavily
* based on the application note 126 "1-Wire Communications Through
* Software".
*
* http://www.maxim-ic.com/appnotes.cfm/appnote_number/126
*/
/*
* For now we stuff in Moteiv Corporation's unique OUI.
* From http://www.ethereal.com/distribution/manuf.txt:
* 00:12:75 Moteiv # Moteiv Corporation
*
* The EUI-64 is a concatenation of the 24-bit OUI value assigned by
* the IEEE Registration Authority and a 40-bit extension identifier
* assigned by the organization with that OUI assignment.
*/
#include <string.h>
#include "contiki.h"
#include "dev/ds2411/ds2411.h"
unsigned char ds2411_id[8];
#ifdef CONTIKI_TARGET_SKY
/* 1-wire is at p2.4 */
#define PIN BV(4)
#define PIN_INIT() {\
P2DIR &= ~PIN; /* p2.4 in, resistor pull high */\
P2OUT &= ~PIN; /* p2.4 == 0 but still input */\
}
/* Set 1-Wire low or high. */
#define OUTP_0() (P2DIR |= PIN) /* output and p2.4 == 0 from above */
#define OUTP_1() (P2DIR &= ~PIN) /* p2.4 in, external resistor pull high */
/* Read one bit. */
#define INP() (P2IN & PIN)
/*
* Delay for u microseconds on a MSP430 at 2.4756MHz.
*
* The loop in clock_delay consists of one add and one jnz, i.e 3
* cycles.
*
* 3 cycles at 2.4756MHz ==> 1.2us = 6/5us.
*
* Call overhead is roughly 7 cycles and the loop 3 cycles, to
* compensate for call overheads we make 7/3=14/6 fewer laps in the
* loop.
*
* This macro will loose badly if not passed a constant argument, it
* relies on the compiler doing the arithmetic during compile time!!
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* TODO: Fix above comment to be correct - below code is modified for 4Mhz
*/
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#define udelay(u) clock_delay((u*8 - 14)/6)
/*
* Where call overhead dominates, use a macro!
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* Note: modified for 4 Mhz
*/
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#define udelay_6() { _NOP(); _NOP(); _NOP(); _NOP(); _NOP(); _NOP(); _NOP(); }
#endif /* CONTIKI_TARGET_SKY */
/*
* Recommended delay times in us.
*/
#define udelay_tA() udelay_6()
/* tA 6 max 15 */
#define tB 64
#define tC 60 /* max 120 */
#define tD 10
#define tE 9 /* max 12 */
#define tF 55
#define tG 0
#define tH 480
#define tI 70
#define tJ 410
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/*---------------------------------------------------------------------------*/
static int
owreset(void)
{
int result;
OUTP_0();
udelay(tH);
OUTP_1(); /* Releases the bus */
udelay(tI);
result = INP();
udelay(tJ);
return result;
}
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/*---------------------------------------------------------------------------*/
static void
owwriteb(unsigned byte)
{
int i = 7;
do {
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if(byte & 0x01) {
OUTP_0();
udelay_tA();
OUTP_1(); /* Releases the bus */
udelay(tB);
} else {
OUTP_0();
udelay(tC);
OUTP_1(); /* Releases the bus */
udelay(tD);
}
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if(i == 0) {
return;
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}
i--;
byte >>= 1;
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} while(1);
}
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/*---------------------------------------------------------------------------*/
static unsigned
owreadb(void)
{
unsigned result = 0;
int i = 7;
do {
OUTP_0();
udelay_tA();
OUTP_1(); /* Releases the bus */
udelay(tE);
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if(INP()) {
result |= 0x80; /* LSbit first */
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}
udelay(tF);
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if(i == 0) {
return result;
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}
i--;
result >>= 1;
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} while(1);
}
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/*---------------------------------------------------------------------------*/
/* Polynomial ^8 + ^5 + ^4 + 1 */
static unsigned
crc8_add(unsigned acc, unsigned byte)
{
int i;
acc ^= byte;
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for(i = 0; i < 8; i++) {
if(acc & 1) {
acc = (acc >> 1) ^ 0x8c;
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} else {
acc >>= 1;
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}
}
return acc;
}
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/*---------------------------------------------------------------------------*/
int
ds2411_init()
{
int i;
unsigned family, crc, acc;
PIN_INIT();
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if(owreset() == 0) { /* Something pulled down 1-wire. */
/*
* Read MAC id with interrupts disabled.
*/
int s = splhigh();
owwriteb(0x33); /* Read ROM command. */
family = owreadb();
/* We receive 6 bytes in the reverse order, LSbyte first. */
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for(i = 7; i >= 2; i--) {
ds2411_id[i] = owreadb();
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}
crc = owreadb();
splx(s);
/* Verify family and that CRC match. */
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if(family != 0x01) {
goto fail;
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}
acc = crc8_add(0x0, family);
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for(i = 7; i >= 2; i--) {
acc = crc8_add(acc, ds2411_id[i]);
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}
if(acc == crc) {
#ifdef CONTIKI_TARGET_SKY
/* 00:12:75 Moteiv # Moteiv Corporation */
ds2411_id[0] = 0x00;
ds2411_id[1] = 0x12;
ds2411_id[2] = 0x75;
#endif /* CONTIKI_TARGET_SKY */
return 1; /* Success! */
}
}
fail:
memset(ds2411_id, 0x0, sizeof(ds2411_id));
return 0; /* Fail! */
}
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/*---------------------------------------------------------------------------*/