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annotate simple_ds18b20.c @ 154:542efb356e46
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| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Thu, 20 Dec 2012 22:26:33 +0800 |
| parents | 295a4b875677 |
| children |
| rev | line source |
|---|---|
| 12 | 1 // Matt Johnston 2012 |
| 2 // Based on ds18x20.c by Martin Thomas, in turn based on code by | |
| 3 // Peter // Dannegger and others. | |
| 4 // | |
| 5 #include <stdio.h> | |
| 6 #include <avr/pgmspace.h> | |
| 7 | |
| 8 #include "ds18x20.h" | |
| 9 #include "onewire.h" | |
| 10 #include "crc8.h" | |
| 11 | |
| 12 #include "simple_ds18b20.h" | |
| 13 | |
| 14 uint8_t | |
| 15 simple_ds18b20_start_meas(uint8_t id[]) | |
| 16 { | |
| 17 uint8_t ret; | |
| 18 | |
| 19 ow_reset(); | |
| 20 if( ow_input_pin_state() ) { // only send if bus is "idle" = high | |
| 21 ow_command_with_parasite_enable(DS18X20_CONVERT_T, id); | |
| 22 ret = DS18X20_OK; | |
| 23 } | |
| 24 else { | |
| 25 ret = DS18X20_START_FAIL; | |
| 26 } | |
| 27 | |
| 28 return ret; | |
| 29 } | |
| 30 | |
| 31 static uint8_t | |
| 32 read_scratchpad( uint8_t id[], uint8_t sp[], uint8_t n ) | |
| 33 { | |
| 34 uint8_t i; | |
| 35 uint8_t ret; | |
| 36 | |
| 37 ow_command( DS18X20_READ, id ); | |
| 38 for ( i = 0; i < n; i++ ) { | |
| 39 sp[i] = ow_byte_rd(); | |
| 40 } | |
| 41 if ( crc8( &sp[0], DS18X20_SP_SIZE ) ) { | |
| 42 ret = DS18X20_ERROR_CRC; | |
| 43 } else { | |
| 44 ret = DS18X20_OK; | |
| 45 } | |
| 46 | |
| 47 return ret; | |
| 48 } | |
| 49 | |
| 115 | 50 int16_t |
| 51 ds18b20_raw16_to_decicelsius(uint16_t measure) | |
| 12 | 52 { |
| 53 uint8_t negative; | |
| 54 int16_t decicelsius; | |
| 55 uint16_t fract; | |
| 56 | |
| 57 // check for negative | |
| 58 if ( measure & 0x8000 ) { | |
| 59 negative = 1; // mark negative | |
| 60 measure ^= 0xffff; // convert to positive => (twos complement)++ | |
| 61 measure++; | |
| 62 } | |
| 63 else { | |
| 64 negative = 0; | |
| 65 } | |
| 66 | |
| 67 decicelsius = (measure >> 4); | |
| 68 decicelsius *= 10; | |
| 69 | |
| 70 // decicelsius += ((measure & 0x000F) * 640 + 512) / 1024; | |
| 71 // 625/1000 = 640/1024 | |
| 72 fract = ( measure & 0x000F ) * 640; | |
| 73 if ( !negative ) { | |
| 74 fract += 512; | |
| 75 } | |
| 76 fract /= 1024; | |
| 77 decicelsius += fract; | |
| 78 | |
| 79 if ( negative ) { | |
| 80 decicelsius = -decicelsius; | |
| 81 } | |
| 82 | |
| 120 | 83 if ( decicelsius == 850 || decicelsius < -550 || decicelsius > 1250 ) { |
| 12 | 84 return DS18X20_INVALID_DECICELSIUS; |
| 85 } else { | |
| 86 return decicelsius; | |
| 87 } | |
| 88 } | |
| 89 | |
| 90 uint8_t | |
| 91 simple_ds18b20_read_decicelsius( uint8_t id[], int16_t *decicelsius ) | |
| 92 { | |
| 115 | 93 uint16_t reading; |
| 12 | 94 uint8_t ret; |
| 115 | 95 |
| 96 ret = simple_ds18b20_read_raw(id, &reading); | |
| 97 if (ret == DS18X20_OK) | |
| 98 { | |
| 99 *decicelsius = ds18b20_raw16_to_decicelsius(reading); | |
| 100 } | |
| 101 return ret; | |
| 12 | 102 } |
| 103 | |
|
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104 uint8_t |
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105 simple_ds18b20_read_raw( uint8_t id[], uint16_t *reading ) |
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106 { |
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107 uint8_t sp[DS18X20_SP_SIZE]; |
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108 uint8_t ret; |
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109 |
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110 if (id) |
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111 { |
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112 ow_reset(); |
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113 } |
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114 ret = read_scratchpad( id, sp, DS18X20_SP_SIZE ); |
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115 if ( ret == DS18X20_OK ) { |
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116 *reading = sp[0] | (sp[1] << 8); |
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117 } |
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118 return ret; |
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119 } |
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120 |
| 12 | 121 static void |
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122 printhex_nibble(const unsigned char b, FILE *stream) |
| 12 | 123 { |
| 124 unsigned char c = b & 0x0f; | |
| 125 if ( c > 9 ) { | |
| 126 c += 'A'-10; | |
| 127 } | |
| 128 else { | |
| 129 c += '0'; | |
| 130 } | |
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131 fputc(c, stream); |
| 12 | 132 } |
| 133 | |
| 134 void | |
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135 printhex_byte(const unsigned char b, FILE *stream) |
| 12 | 136 { |
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137 printhex_nibble( b >> 4, stream); |
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138 printhex_nibble( b, stream); |
| 12 | 139 } |
| 140 | |
| 141 void | |
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142 printhex(uint8_t *id, uint8_t n, FILE *stream) |
| 12 | 143 { |
| 144 for (uint8_t i = 0; i < n; i++) | |
| 145 { | |
| 146 if (i > 0) | |
| 147 { | |
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148 fputc(' ', stream); |
| 12 | 149 } |
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150 printhex_byte(id[i], stream); |
| 12 | 151 } |
| 152 } | |
| 153 | |
| 154 | |
| 155 uint8_t | |
| 156 simple_ds18b20_read_all() | |
| 157 { | |
| 158 uint8_t id[OW_ROMCODE_SIZE]; | |
| 159 for( uint8_t diff = OW_SEARCH_FIRST; diff != OW_LAST_DEVICE; ) | |
| 160 { | |
| 161 diff = ow_rom_search( diff, &id[0] ); | |
| 162 | |
| 163 if( diff == OW_PRESENCE_ERR ) { | |
| 164 printf_P( PSTR("No Sensor found\r") ); | |
| 165 return OW_PRESENCE_ERR; // <--- early exit! | |
| 166 } | |
| 167 | |
| 168 if( diff == OW_DATA_ERR ) { | |
| 169 printf_P( PSTR("Bus Error\r") ); | |
| 170 return OW_DATA_ERR; // <--- early exit! | |
| 171 } | |
| 172 | |
| 173 int16_t decicelsius; | |
| 174 uint8_t ret = simple_ds18b20_read_decicelsius(NULL, &decicelsius); | |
| 175 if (ret != DS18X20_OK) | |
| 176 { | |
| 177 printf_P(PSTR("Failed reading\r")); | |
| 178 return OW_DATA_ERR; | |
| 179 } | |
| 180 | |
| 181 printf_P(PSTR("DS18B20 %d: "), diff); | |
| 182 if (crc8(id, OW_ROMCODE_SIZE)) | |
| 183 { | |
| 184 printf_P(PSTR("CRC fail")); | |
| 185 } | |
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186 printhex(id, OW_ROMCODE_SIZE, stdout); |
| 12 | 187 printf_P(PSTR(" %d.%d ºC\n"), decicelsius/10, decicelsius % 10); |
| 188 } | |
| 189 printf_P(PSTR("Done sensors\n")); | |
| 190 return DS18X20_OK; | |
| 191 } | |
| 192 |