235 lines
6.2 KiB
C
235 lines
6.2 KiB
C
/*
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* Copyright (c) 2005, Swedish Institute of Computer Science
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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*/
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/*
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* Device driver for the Dallas Semiconductor DS2411 chip. Heavily
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* based on the application note 126 "1-Wire Communications Through
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* Software".
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*
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* http://www.maxim-ic.com/appnotes.cfm/appnote_number/126
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*/
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/*
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* For now we stuff in Moteiv Corporation's unique OUI.
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* From http://www.ethereal.com/distribution/manuf.txt:
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* 00:12:75 Moteiv # Moteiv Corporation
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*
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* The EUI-64 is a concatenation of the 24-bit OUI value assigned by
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* the IEEE Registration Authority and a 40-bit extension identifier
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* assigned by the organization with that OUI assignment.
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*/
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#include <string.h>
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#include "contiki.h"
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#include "dev/ds2411.h"
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unsigned char ds2411_id[8];
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#ifdef CONTIKI_TARGET_SKY
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/* 1-wire is at p2.4 */
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#define PIN BV(4)
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#define PIN_INIT() {\
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P2DIR &= ~PIN; /* p2.4 in, resistor pull high */\
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P2OUT &= ~PIN; /* p2.4 == 0 but still input */\
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}
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/* Set 1-Wire low or high. */
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#define OUTP_0() (P2DIR |= PIN) /* output and p2.4 == 0 from above */
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#define OUTP_1() (P2DIR &= ~PIN) /* p2.4 in, external resistor pull high */
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/* Read one bit. */
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#define INP() (P2IN & PIN)
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/*
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* Delay for u microseconds on a MSP430 at 2.4756MHz.
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*
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* The loop in clock_delay consists of one add and one jnz, i.e 3
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* cycles.
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*
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* 3 cycles at 2.4756MHz ==> 1.2us = 6/5us.
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*
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* Call overhead is roughly 7 cycles and the loop 3 cycles, to
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* compensate for call overheads we make 7/3=14/6 fewer laps in the
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* loop.
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*
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* This macro will loose badly if not passed a constant argument, it
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* 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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*/
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#define udelay(u) clock_delay((u*8 - 14)/6)
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/*
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* Where call overhead dominates, use a macro!
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* Note: modified for 4 Mhz
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*/
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#define udelay_6() { _NOP(); _NOP(); _NOP(); _NOP(); _NOP(); _NOP(); _NOP(); }
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#endif /* CONTIKI_TARGET_SKY */
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/*
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* Recommended delay times in us.
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*/
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#define udelay_tA() udelay_6()
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/* tA 6 max 15 */
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#define tB 64
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#define tC 60 /* max 120 */
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#define tD 10
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#define tE 9 /* max 12 */
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#define tF 55
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#define tG 0
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#define tH 480
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#define tI 70
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#define tJ 410
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/*---------------------------------------------------------------------------*/
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static int
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owreset(void)
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{
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int result;
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OUTP_0();
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udelay(tH);
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OUTP_1(); /* Releases the bus */
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udelay(tI);
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result = INP();
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udelay(tJ);
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return result;
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}
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/*---------------------------------------------------------------------------*/
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static void
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owwriteb(unsigned byte)
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{
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int i = 7;
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do {
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if(byte & 0x01) {
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OUTP_0();
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udelay_tA();
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OUTP_1(); /* Releases the bus */
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udelay(tB);
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} else {
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OUTP_0();
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udelay(tC);
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OUTP_1(); /* Releases the bus */
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udelay(tD);
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}
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if(i == 0) {
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return;
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}
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i--;
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byte >>= 1;
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} while(1);
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}
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/*---------------------------------------------------------------------------*/
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static unsigned
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owreadb(void)
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{
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unsigned result = 0;
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int i = 7;
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do {
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OUTP_0();
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udelay_tA();
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OUTP_1(); /* Releases the bus */
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udelay(tE);
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if(INP()) {
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result |= 0x80; /* LSbit first */
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}
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udelay(tF);
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if(i == 0) {
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return result;
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}
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i--;
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result >>= 1;
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} while(1);
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}
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/*---------------------------------------------------------------------------*/
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/* Polynomial ^8 + ^5 + ^4 + 1 */
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static unsigned
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crc8_add(unsigned acc, unsigned byte)
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{
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int i;
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acc ^= byte;
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for(i = 0; i < 8; i++) {
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if(acc & 1) {
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acc = (acc >> 1) ^ 0x8c;
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} else {
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acc >>= 1;
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}
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}
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return acc;
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}
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/*---------------------------------------------------------------------------*/
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int
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ds2411_init()
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{
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int i;
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unsigned family, crc, acc;
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PIN_INIT();
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if(owreset() == 0) { /* Something pulled down 1-wire. */
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/*
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* Read MAC id with interrupts disabled.
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*/
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int s = splhigh();
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owwriteb(0x33); /* Read ROM command. */
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family = owreadb();
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/* We receive 6 bytes in the reverse order, LSbyte first. */
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for(i = 7; i >= 2; i--) {
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ds2411_id[i] = owreadb();
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}
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crc = owreadb();
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splx(s);
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/* Verify family and that CRC match. */
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if(family != 0x01) {
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goto fail;
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}
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acc = crc8_add(0x0, family);
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for(i = 7; i >= 2; i--) {
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acc = crc8_add(acc, ds2411_id[i]);
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}
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if(acc == crc) {
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#ifdef CONTIKI_TARGET_SKY
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/* 00:12:75 Moteiv # Moteiv Corporation */
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ds2411_id[0] = 0x00;
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ds2411_id[1] = 0x12;
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ds2411_id[2] = 0x75;
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#endif /* CONTIKI_TARGET_SKY */
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return 1; /* Success! */
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}
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}
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fail:
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memset(ds2411_id, 0x0, sizeof(ds2411_id));
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return 0; /* Fail! */
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}
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/*---------------------------------------------------------------------------*/
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