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annotate simple_ds18b20.c @ 98:dbcbda1e2da2
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| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Mon, 16 Jul 2012 22:58:33 +0800 |
| parents | ca08442635ca |
| children | 90d1ebb941ab |
| 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 | |
| 50 static int16_t | |
| 51 ds18b20_raw_to_decicelsius( uint8_t sp[] ) | |
| 52 { | |
| 53 uint16_t measure; | |
| 54 uint8_t negative; | |
| 55 int16_t decicelsius; | |
| 56 uint16_t fract; | |
| 57 | |
| 58 measure = sp[0] | (sp[1] << 8); | |
| 59 //measure = 0xFF5E; // test -10.125 | |
| 60 //measure = 0xFE6F; // test -25.0625 | |
| 61 | |
| 62 // check for negative | |
| 63 if ( measure & 0x8000 ) { | |
| 64 negative = 1; // mark negative | |
| 65 measure ^= 0xffff; // convert to positive => (twos complement)++ | |
| 66 measure++; | |
| 67 } | |
| 68 else { | |
| 69 negative = 0; | |
| 70 } | |
| 71 | |
| 72 // clear undefined bits for DS18B20 != 12bit resolution | |
| 73 switch( sp[DS18B20_CONF_REG] & DS18B20_RES_MASK ) { | |
| 74 case DS18B20_9_BIT: | |
| 75 measure &= ~(DS18B20_9_BIT_UNDF); | |
| 76 break; | |
| 77 case DS18B20_10_BIT: | |
| 78 measure &= ~(DS18B20_10_BIT_UNDF); | |
| 79 break; | |
| 80 case DS18B20_11_BIT: | |
| 81 measure &= ~(DS18B20_11_BIT_UNDF); | |
| 82 break; | |
| 83 default: | |
| 84 // 12 bit - all bits valid | |
| 85 break; | |
| 86 } | |
| 87 | |
| 88 decicelsius = (measure >> 4); | |
| 89 decicelsius *= 10; | |
| 90 | |
| 91 // decicelsius += ((measure & 0x000F) * 640 + 512) / 1024; | |
| 92 // 625/1000 = 640/1024 | |
| 93 fract = ( measure & 0x000F ) * 640; | |
| 94 if ( !negative ) { | |
| 95 fract += 512; | |
| 96 } | |
| 97 fract /= 1024; | |
| 98 decicelsius += fract; | |
| 99 | |
| 100 if ( negative ) { | |
| 101 decicelsius = -decicelsius; | |
| 102 } | |
| 103 | |
| 104 if ( /* decicelsius == 850 || */ decicelsius < -550 || decicelsius > 1250 ) { | |
| 105 return DS18X20_INVALID_DECICELSIUS; | |
| 106 } else { | |
| 107 return decicelsius; | |
| 108 } | |
| 109 } | |
| 110 | |
| 111 uint8_t | |
| 112 simple_ds18b20_read_decicelsius( uint8_t id[], int16_t *decicelsius ) | |
| 113 { | |
| 114 uint8_t sp[DS18X20_SP_SIZE]; | |
| 115 uint8_t ret; | |
| 116 | |
| 117 if (id) | |
| 118 { | |
| 119 ow_reset(); | |
| 120 } | |
| 121 ret = read_scratchpad( id, sp, DS18X20_SP_SIZE ); | |
| 122 if ( ret == DS18X20_OK ) { | |
| 123 *decicelsius = ds18b20_raw_to_decicelsius( sp ); | |
| 124 } | |
| 125 return ret; | |
| 126 } | |
| 127 | |
|
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128 uint8_t |
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129 simple_ds18b20_read_raw( uint8_t id[], uint16_t *reading ) |
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130 { |
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131 uint8_t sp[DS18X20_SP_SIZE]; |
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132 uint8_t ret; |
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133 |
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134 if (id) |
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135 { |
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136 ow_reset(); |
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137 } |
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138 ret = read_scratchpad( id, sp, DS18X20_SP_SIZE ); |
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139 if ( ret == DS18X20_OK ) { |
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140 *reading = sp[0] | (sp[1] << 8); |
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141 } |
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142 return ret; |
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143 } |
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144 |
| 12 | 145 static void |
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146 printhex_nibble(const unsigned char b, FILE *stream) |
| 12 | 147 { |
| 148 unsigned char c = b & 0x0f; | |
| 149 if ( c > 9 ) { | |
| 150 c += 'A'-10; | |
| 151 } | |
| 152 else { | |
| 153 c += '0'; | |
| 154 } | |
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155 fputc(c, stream); |
| 12 | 156 } |
| 157 | |
| 158 void | |
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159 printhex_byte(const unsigned char b, FILE *stream) |
| 12 | 160 { |
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161 printhex_nibble( b >> 4, stream); |
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162 printhex_nibble( b, stream); |
| 12 | 163 } |
| 164 | |
| 165 void | |
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166 printhex(uint8_t *id, uint8_t n, FILE *stream) |
| 12 | 167 { |
| 168 for (uint8_t i = 0; i < n; i++) | |
| 169 { | |
| 170 if (i > 0) | |
| 171 { | |
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172 fputc(' ', stream); |
| 12 | 173 } |
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174 printhex_byte(id[i], stream); |
| 12 | 175 } |
| 176 } | |
| 177 | |
| 178 | |
| 179 uint8_t | |
| 180 simple_ds18b20_read_all() | |
| 181 { | |
| 182 uint8_t id[OW_ROMCODE_SIZE]; | |
| 183 for( uint8_t diff = OW_SEARCH_FIRST; diff != OW_LAST_DEVICE; ) | |
| 184 { | |
| 185 diff = ow_rom_search( diff, &id[0] ); | |
| 186 | |
| 187 if( diff == OW_PRESENCE_ERR ) { | |
| 188 printf_P( PSTR("No Sensor found\r") ); | |
| 189 return OW_PRESENCE_ERR; // <--- early exit! | |
| 190 } | |
| 191 | |
| 192 if( diff == OW_DATA_ERR ) { | |
| 193 printf_P( PSTR("Bus Error\r") ); | |
| 194 return OW_DATA_ERR; // <--- early exit! | |
| 195 } | |
| 196 | |
| 197 int16_t decicelsius; | |
| 198 uint8_t ret = simple_ds18b20_read_decicelsius(NULL, &decicelsius); | |
| 199 if (ret != DS18X20_OK) | |
| 200 { | |
| 201 printf_P(PSTR("Failed reading\r")); | |
| 202 return OW_DATA_ERR; | |
| 203 } | |
| 204 | |
| 205 printf_P(PSTR("DS18B20 %d: "), diff); | |
| 206 if (crc8(id, OW_ROMCODE_SIZE)) | |
| 207 { | |
| 208 printf_P(PSTR("CRC fail")); | |
| 209 } | |
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210 printhex(id, OW_ROMCODE_SIZE, stdout); |
| 12 | 211 printf_P(PSTR(" %d.%d ºC\n"), decicelsius/10, decicelsius % 10); |
| 212 } | |
| 213 printf_P(PSTR("Done sensors\n")); | |
| 214 return DS18X20_OK; | |
| 215 } | |
| 216 |