annotate 1wire.c @ 30:48056516b3eb

Make sure our outputs are pulled high.
author darius
date Mon, 10 Apr 2006 17:23:51 +0930
parents 02b67e09ca12
children b0cb873c0206
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1 /*
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2 * Various 1 wire routines
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3 * Search routine is copied from the Dallas owpd library with mods
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4 * available from here http://www.ibutton.com/software/1wire/wirekit.html
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5 *
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6 * $Id$
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7 *
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8 * Copyright (c) 2004
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9 * Daniel O'Connor <darius@dons.net.au>. All rights reserved.
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10 *
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11 * Redistribution and use in source and binary forms, with or without
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12 * modification, are permitted provided that the following conditions
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13 * are met:
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14 * 1. Redistributions of source code must retain the above copyright
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15 * notice, this list of conditions and the following disclaimer.
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16 * 2. Redistributions in binary form must reproduce the above copyright
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17 * notice, this list of conditions and the following disclaimer in the
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18 * documentation and/or other materials provided with the distribution.
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19 *
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20 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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23 * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
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24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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30 * SUCH DAMAGE.
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31 */
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32
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33 #include <stdio.h>
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34 #include <avr/io.h>
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35 #include <avr/pgmspace.h>
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36 #include <util/delay.h>
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37 #include "1wire.h"
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38 #include "1wire-delay.h"
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39
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40 #if OW_DEBUG
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41 void uart_putsP(const char *addr);
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42 void uart_puts(const char *addr);
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43 void uart_getc();
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44 char uart_putc(char c);
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45 #endif
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46
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47 static uint8_t OW_LastDevice = 0;
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48 static uint8_t OW_LastDiscrepancy = 0;
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49 static uint8_t OW_LastFamilyDiscrepancy = 0;
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50
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51 static void
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52 OWdelay(void) {
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53 DELAY_I;
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54 }
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55
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56 /*-----------------------------------------------------------------------------
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57 * Generate a 1-Wire reset, return 0 if presence pulse was found, 1 if it
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58 * wasn't, or 2 if the line appears to be being held low.
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59 *
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60 * (NOTE: Does not handle alarm presence from DS2404/DS1994)
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61 */
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62 uint8_t
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63 OWTouchReset(void) {
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64 DELAY_G;
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65
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66 if (!(OWIREINPORT & _BV(OWIREINPIN)))
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67 return 2;
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68
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69 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
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70 OWIREDDR |= _BV(OWIREOUTPIN);
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71 DELAY_H;
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72 OWIREDDR &= ~(_BV(OWIREOUTPIN));
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73 DELAY_I;
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74
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75 return(OWIREINPORT & _BV(OWIREINPIN) ? 1 : 0);
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76 }
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77
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78 /*-----------------------------------------------------------------------------
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79 * Send a 1-wire write bit.
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80 */
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81 void
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82 OWWriteBit(uint8_t bit) {
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83 OWdelay();
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84 if (bit) {
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85 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
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86 OWIREDDR |= _BV(OWIREOUTPIN);
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87 DELAY_A;
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88 OWIREDDR &= ~(_BV(OWIREOUTPIN));
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89 DELAY_B;
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90 } else {
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91 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
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92 OWIREDDR |= _BV(OWIREOUTPIN);
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93 DELAY_C;
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94 OWIREDDR &= ~(_BV(OWIREOUTPIN));
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95 DELAY_D;
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96 }
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97 }
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98
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99 /*-----------------------------------------------------------------------------
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100 * Read a bit from the 1-wire bus and return it.
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101 */
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102 uint8_t
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103 OWReadBit(void) {
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104 OWdelay();
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105
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106 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
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107 OWIREDDR |= _BV(OWIREOUTPIN);
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108 DELAY_A;
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109 OWIREDDR &= ~(_BV(OWIREOUTPIN));
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110 DELAY_E;
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111 return(OWIREINPORT & _BV(OWIREINPIN) ? 1 : 0);
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112 }
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113
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114 /*-----------------------------------------------------------------------------
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115 * Write a byte to the 1-wire bus
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116 */
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117 void
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118 OWWriteByte(uint8_t data) {
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119 uint8_t i;
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120
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121 /* Send LSB first */
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122 for (i = 0; i < 8; i++) {
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123 OWWriteBit(data & 0x01);
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124 data >>= 1;
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125 }
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126 }
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127
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128 /*-----------------------------------------------------------------------------
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129 * Read a byte from the 1-wire bus
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130 */
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131 uint8_t
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132 OWReadByte(void) {
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133 int i, result = 0;
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134
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135 for (i = 0; i < 8; i++) {
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136 result >>= 1;
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137 if (OWReadBit())
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138 result |= 0x80;
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139 }
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140 return(result);
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141 }
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142
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143 /*-----------------------------------------------------------------------------
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144 * Write a 1-wire data byte and return the sampled result.
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145 */
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146 uint8_t
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147 OWTouchByte(uint8_t data) {
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148 uint8_t i, result = 0;
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149
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150 for (i = 0; i < 8; i++) {
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151 result >>= 1;
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152
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153 /* If sending a 1 then read a bit, otherwise write a 0 */
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154 if (data & 0x01) {
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155 if (OWReadBit())
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156 result |= 0x80;
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157 } else
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158 OWWriteBit(0);
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159
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160 data >>= 1;
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161 }
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162
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163 return(result);
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164 }
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165
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166 /*-----------------------------------------------------------------------------
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167 * Write a block of bytes to the 1-wire bus and return the sampled result in
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168 * the same buffer
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169 */
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170 void
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171 OWBlock(uint8_t *data, int len) {
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172 int i;
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173
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174 for (i = 0; i < len; i++)
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175 data[i] = OWTouchByte(data[i]);
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176 }
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177
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178
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179 /*-----------------------------------------------------------------------------
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180 * Send a 1 wire command to a device, or all if no ROM ID provided
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181 */
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182 void
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183 OWSendCmd(uint8_t *ROM, uint8_t cmd) {
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184 uint8_t i;
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185
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186 OWTouchReset();
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187
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188 if (ROM == NULL)
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189 OWWriteByte(OW_SKIP_ROM_CMD);
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190 else {
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191 OWWriteByte(OW_MATCH_ROM_CMD);
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192 for (i = 0; i < 8; i++)
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193 OWWriteByte(ROM[i]);
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194 }
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195
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196 OWWriteByte(cmd);
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197 }
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198
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199 /*-----------------------------------------------------------------------------
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200 * Search algorithm from App note 187 (and 162)
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201 *
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202 * OWFirst/OWNext return..
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203 * 1 when something is found,
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204 * 0 no more modules
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026dc24d85e0 Spell presence correctly.
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205 * -1 if no presence pulse,
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206 * -2 if bad CRC,
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207 * -3 if bad wiring.
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208 */
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209 uint8_t
0
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210 OWFirst(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) {
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211 /* Reset state */
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212 OW_LastDiscrepancy = 0;
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213 OW_LastDevice = 0;
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214 OW_LastFamilyDiscrepancy = 0;
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215
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216 /* Go looking */
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217 return (OWNext(ROM, do_reset, alarm_only));
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218 }
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219
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220 /* Returns 1 when something is found, 0 if nothing left */
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221 uint8_t
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222 OWNext(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) {
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223 uint8_t bit_test, search_direction, bit_number;
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224 uint8_t last_zero, rom_byte_number, rom_byte_mask;
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225 uint8_t lastcrc8, crcaccum;
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226 int8_t next_result;
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227
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228 /* Init for search */
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229 bit_number = 1;
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230 last_zero = 0;
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231 rom_byte_number = 0;
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232 rom_byte_mask = 1;
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233 next_result = OW_NOMODULES;
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234 lastcrc8 = 0;
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235 crcaccum = 0;
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236
21
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237 /* if the last call was not the last one */
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238 if (!OW_LastDevice) {
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239 /* check if reset first is requested */
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240 if (do_reset) {
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241 /* reset the 1-wire
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242 * if there are no parts on 1-wire, return 0 */
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243 #if OW_DEBUG
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244 uart_putsP(PSTR("Resetting\n\r"));
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245 #endif
22
bd792ebf813d Report the bus being held low back to the caller from OWFirst/Next.
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246 switch (OWTouchReset()) {
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247 case 0:
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248 break;
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249
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250 case 1:
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251 /* reset the search */
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252 OW_LastDiscrepancy = 0;
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253 OW_LastFamilyDiscrepancy = 0;
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254 #if OW_DEBUG
22
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255 uart_putsP(PSTR("No devices on bus\n\r"));
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256 #endif
22
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257 return OW_NOPRESENCE;
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258 break;
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259
bd792ebf813d Report the bus being held low back to the caller from OWFirst/Next.
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260 case 2:
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261 /* reset the search */
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262 OW_LastDiscrepancy = 0;
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263 OW_LastFamilyDiscrepancy = 0;
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264 #if OW_DEBUG
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265 uart_putsP(PSTR("Bus appears to be being held low\n\r"));
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266 #endif
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267 return OW_BADWIRE;
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268 break;
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269
21
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270 }
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271 }
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272
21
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273 /* If finding alarming devices issue a different command */
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274 if (alarm_only)
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275 OWWriteByte(OW_SEARCH_ALRM_CMD); /* issue the alarming search command */
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276 else
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277 OWWriteByte(OW_SEARCH_ROM_CMD); /* issue the search command */
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278
21
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279 /* pause before beginning the search */
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280 OWdelay();
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281 OWdelay();
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282 OWdelay();
0
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283
21
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284 /* loop to do the search */
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285 do {
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286 /* read a bit and its compliment */
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287 bit_test = OWReadBit() << 1;
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288 bit_test |= OWReadBit();
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289
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290 #if OW_DEBUG
21
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291 sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test);
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292 uart_puts(errstr);
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293 #endif
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294
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295 /* check for no devices on 1-wire */
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296 if (bit_test == 3) {
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297 #if OW_DEBUG
21
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298 sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test);
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299 uart_puts(errstr);
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300 #endif
21
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301 return(OW_BADWIRE);
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302 }
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303 else {
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304 /* all devices coupled have 0 or 1 */
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305 if (bit_test > 0)
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306 search_direction = !(bit_test & 0x01); /* bit write value for search */
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307 else {
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308 /* if this discrepancy is before the Last Discrepancy
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309 * on a previous OWNext then pick the same as last time */
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310 if (bit_number < OW_LastDiscrepancy)
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311 search_direction = ((ROM[rom_byte_number] & rom_byte_mask) > 0);
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312 else
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313 /* if equal to last pick 1, if not then pick 0 */
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314 search_direction = (bit_number == OW_LastDiscrepancy);
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315
21
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316 /* if 0 was picked then record its position in LastZero */
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317 if (search_direction == 0) {
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318 last_zero = bit_number;
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319
21
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320 /* check for Last discrepancy in family */
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321 if (last_zero < 9)
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322 OW_LastFamilyDiscrepancy = last_zero;
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323 }
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324 }
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325
21
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326 /* set or clear the bit in the ROM byte rom_byte_number
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327 * with mask rom_byte_mask */
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328 if (search_direction == 1)
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329 ROM[rom_byte_number] |= rom_byte_mask;
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330 else
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331 ROM[rom_byte_number] &= ~rom_byte_mask;
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332
21
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333 /* serial number search direction write bit */
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334 OWWriteBit(search_direction);
0
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335
21
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336 /* increment the byte counter bit_number
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diff changeset
337 * and shift the mask rom_byte_mask */
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338 bit_number++;
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339 rom_byte_mask <<= 1;
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340
21
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341 /* if the mask is 0 then go to new ROM byte rom_byte_number
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342 * and reset mask */
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parents: 16
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343 if (rom_byte_mask == 0) {
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344 OWCRC(ROM[rom_byte_number], &crcaccum); /* accumulate the CRC */
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345 lastcrc8 = crcaccum;
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346
21
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347 rom_byte_number++;
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348 rom_byte_mask = 1;
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349 }
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350 }
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351 } while (rom_byte_number < 8); /* loop until through all ROM bytes 0-7 */
0
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352
21
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diff changeset
353 /* if the search was successful then */
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parents: 16
diff changeset
354 if (!(bit_number < 65) || lastcrc8) {
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parents: 16
diff changeset
355 if (lastcrc8) {
12
4b141cc7cbd4 - Reduce type widths where possible.
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parents: 10
diff changeset
356 #if OW_DEBUG
21
e82d15fa9a1a Re-format the code.
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diff changeset
357 sprintf_P(errstr, PSTR("Bad CRC (%d)\n\r"), lastcrc8);
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
358 uart_puts(errstr);
12
4b141cc7cbd4 - Reduce type widths where possible.
darius
parents: 10
diff changeset
359 #endif
21
e82d15fa9a1a Re-format the code.
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diff changeset
360 next_result = OW_BADCRC;
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
361 } else {
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parents: 16
diff changeset
362 /* search successful so set LastDiscrepancy,LastDevice,next_result */
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
363 OW_LastDiscrepancy = last_zero;
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
364 OW_LastDevice = (OW_LastDiscrepancy == 0);
0
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diff changeset
365 #if OW_DEBUG
21
e82d15fa9a1a Re-format the code.
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diff changeset
366 sprintf_P(errstr, PSTR("Last device = %d\n\r"), OW_LastDevice);
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
367 uart_puts(errstr);
0
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parents:
diff changeset
368 #endif
21
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
369 next_result = OW_FOUND;
e82d15fa9a1a Re-format the code.
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diff changeset
370 }
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
371 }
e82d15fa9a1a Re-format the code.
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diff changeset
372 }
0
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373
21
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parents: 16
diff changeset
374 /* if no device found then reset counters so next 'next' will be
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
375 * like a first */
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parents: 16
diff changeset
376 if (next_result != OW_FOUND || ROM[0] == 0) {
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
377 OW_LastDiscrepancy = 0;
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parents: 16
diff changeset
378 OW_LastDevice = 0;
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parents: 16
diff changeset
379 OW_LastFamilyDiscrepancy = 0;
e82d15fa9a1a Re-format the code.
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parents: 16
diff changeset
380 }
0
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381
21
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diff changeset
382 if (next_result == OW_FOUND && ROM[0] == 0x00)
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parents: 16
diff changeset
383 next_result = OW_BADWIRE;
10
eb1faf51968e - Add some useful return values to search functions.
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parents: 8
diff changeset
384
21
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diff changeset
385 return next_result;
0
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parents:
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386
ffeab3c04e83 Initial revision
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parents:
diff changeset
387 }
ffeab3c04e83 Initial revision
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parents:
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388
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389 uint8_t PROGMEM dscrc_table[] = {
ffeab3c04e83 Initial revision
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parents:
diff changeset
390 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
ffeab3c04e83 Initial revision
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diff changeset
391 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
ffeab3c04e83 Initial revision
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parents:
diff changeset
392 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
ffeab3c04e83 Initial revision
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parents:
diff changeset
393 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
ffeab3c04e83 Initial revision
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parents:
diff changeset
394 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
ffeab3c04e83 Initial revision
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parents:
diff changeset
395 219, 133,103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
ffeab3c04e83 Initial revision
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parents:
diff changeset
396 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
ffeab3c04e83 Initial revision
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parents:
diff changeset
397 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
ffeab3c04e83 Initial revision
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parents:
diff changeset
398 140,210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113,147, 205,
ffeab3c04e83 Initial revision
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parents:
diff changeset
399 17, 79, 173, 243, 112, 46, 204, 146, 211,141, 111, 49, 178, 236, 14, 80,
ffeab3c04e83 Initial revision
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parents:
diff changeset
400 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82,176, 238,
ffeab3c04e83 Initial revision
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parents:
diff changeset
401 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
ffeab3c04e83 Initial revision
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parents:
diff changeset
402 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
ffeab3c04e83 Initial revision
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parents:
diff changeset
403 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
ffeab3c04e83 Initial revision
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parents:
diff changeset
404 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
ffeab3c04e83 Initial revision
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parents:
diff changeset
405 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
ffeab3c04e83 Initial revision
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parents:
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406 };
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407
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408 void
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409 OWCRC(uint8_t x, uint8_t *crc) {
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410 *crc = pgm_read_byte(&dscrc_table[(*crc) ^ x]);
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411 }