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DS1820.cpp

00001 #include "DS1820.h"
00002 
00003 #ifdef TARGET_STM
00004 //STM targets use opendrain mode since their switching between input and output is slow
00005     #define ONEWIRE_INPUT(pin)  pin->write(1)
00006     #define ONEWIRE_OUTPUT(pin) 
00007     #define ONEWIRE_INIT(pin)   pin->output(); pin->mode(OpenDrain)
00008 #else
00009     #define ONEWIRE_INPUT(pin)  pin->input()
00010     #define ONEWIRE_OUTPUT(pin) pin->output()
00011     #define ONEWIRE_INIT(pin)
00012 #endif
00013 
00014 #ifdef TARGET_NORDIC
00015 //NORDIC targets (NRF) use software delays since their ticker uses a 32kHz clock
00016     static uint32_t loops_per_us = 0;
00017     
00018     #define INIT_DELAY      init_soft_delay()
00019     #define ONEWIRE_DELAY_US(value) for(int cnt = 0; cnt < (value * loops_per_us) >> 5; cnt++) {__NOP(); __NOP(); __NOP();}
00020     
00021 void init_soft_delay( void ) {
00022     if (loops_per_us == 0) {
00023         loops_per_us = 1;
00024         Timer timey; 
00025         timey.start();
00026         ONEWIRE_DELAY_US(320000);                     
00027         timey.stop();
00028         loops_per_us = (320000 + timey.read_us() / 2) / timey.read_us();  
00029     }
00030 }
00031 #else
00032     #define INIT_DELAY
00033     #define ONEWIRE_DELAY_US(value) wait_us(value)
00034 #endif
00035 
00036 LinkedList<node> DS1820::probes;
00037  
00038  
00039 DS1820::DS1820 (PinName data_pin, PinName power_pin, bool power_polarity) : _datapin(data_pin), _parasitepin(power_pin) {
00040     int byte_counter;
00041     _power_polarity = power_polarity;
00042 
00043     _power_mosfet = power_pin != NC;
00044     
00045     for(byte_counter=0;byte_counter<9;byte_counter++)
00046         RAM[byte_counter] = 0x00;
00047     
00048     ONEWIRE_INIT((&_datapin));
00049     INIT_DELAY;
00050     
00051     if (!unassignedProbe(&_datapin, _ROM)) {
00052         printf("DS18B20:No unassigned DS1820 found!\r\n");
00053         valid = false;
00054     }
00055     else {
00056         _datapin.input();
00057         probes.append(this);
00058         _parasite_power = !read_power_supply();
00059         valid = true;
00060     }
00061 }
00062 
00063 DS1820::~DS1820 (void) {
00064     node *tmp;
00065     for(uint32_t i=1; i<=probes.length(); i++)
00066     {
00067         tmp = probes.pop(i);
00068         if (tmp->data == this)
00069             probes.remove(i);
00070     }
00071 }
00072 
00073  
00074 bool DS1820::onewire_reset(DigitalInOut *pin) {
00075 // This will return false if no devices are present on the data bus
00076     bool presence=false;
00077     ONEWIRE_OUTPUT(pin);
00078     pin->write(0);          // bring low for 500 us
00079     ONEWIRE_DELAY_US(500);
00080     ONEWIRE_INPUT(pin);       // let the data line float high
00081     ONEWIRE_DELAY_US(90);            // wait 90us
00082     if (pin->read()==0) // see if any devices are pulling the data line low
00083         presence=true;
00084     ONEWIRE_DELAY_US(410);
00085     return presence;
00086 }
00087  
00088 void DS1820::onewire_bit_out (DigitalInOut *pin, bool bit_data) {
00089     ONEWIRE_OUTPUT(pin);
00090     pin->write(0);
00091     ONEWIRE_DELAY_US(3);                 // DXP modified from 5
00092     if (bit_data) {
00093         pin->write(1); // bring data line high
00094         ONEWIRE_DELAY_US(55);
00095     } else {
00096         ONEWIRE_DELAY_US(55);            // keep data line low
00097         pin->write(1);
00098         ONEWIRE_DELAY_US(10);            // DXP added to allow bus to float high before next bit_out
00099     }
00100 }
00101  
00102 void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
00103     int n;
00104     for (n=0; n<8; n++) {
00105         onewire_bit_out(&this->_datapin, data & 0x01);
00106         data = data >> 1; // now the next bit is in the least sig bit position.
00107     }
00108 }
00109  
00110 bool DS1820::onewire_bit_in(DigitalInOut *pin) {
00111     bool answer;
00112     ONEWIRE_OUTPUT(pin);
00113     pin->write(0);
00114     ONEWIRE_DELAY_US(3);                 // DXP modofied from 5
00115     ONEWIRE_INPUT(pin);
00116     ONEWIRE_DELAY_US(10);                // DXP modified from 5
00117     answer = pin->read();
00118     ONEWIRE_DELAY_US(45);                // DXP modified from 50
00119     return answer;
00120 }
00121  
00122 char DS1820::onewire_byte_in() { // read byte, least sig byte first
00123     char answer = 0x00;
00124     int i;
00125     for (i=0; i<8; i++) {
00126         answer = answer >> 1; // shift over to make room for the next bit
00127         if (onewire_bit_in(&this->_datapin))
00128             answer = answer | 0x80; // if the data port is high, make this bit a 1
00129     }
00130     return answer;
00131 }
00132 
00133 bool DS1820::unassignedProbe(PinName pin) {
00134     DigitalInOut _pin(pin);
00135     ONEWIRE_INIT((&_pin));
00136     INIT_DELAY;
00137     char ROM_address[8];
00138     return search_ROM_routine(&_pin, 0xF0, ROM_address);
00139 }
00140  
00141 bool DS1820::unassignedProbe(DigitalInOut *pin, char *ROM_address) {
00142     return search_ROM_routine(pin, 0xF0, ROM_address);
00143 }
00144  
00145 bool DS1820::search_ROM_routine(DigitalInOut *pin, char command, char *ROM_address) {
00146     bool DS1820_done_flag = false;
00147     int DS1820_last_descrepancy = 0;
00148     char DS1820_search_ROM[8] = {0, 0, 0, 0, 0, 0, 0, 0};
00149     
00150     int descrepancy_marker, ROM_bit_index;
00151     bool return_value, Bit_A, Bit_B;
00152     char bit_mask;
00153     int byte_counter;
00154  
00155     return_value=false;
00156     while (!DS1820_done_flag) {
00157         if (!onewire_reset(pin)) {
00158             return false;
00159         } else {
00160             ROM_bit_index=1;
00161             descrepancy_marker=0;
00162             char command_shift = command;
00163             for (int n=0; n<8; n++) {           // Search ROM command or Search Alarm command
00164                 onewire_bit_out(pin, command_shift & 0x01);
00165                 command_shift = command_shift >> 1; // now the next bit is in the least sig bit position.
00166             } 
00167             byte_counter = 0;
00168             bit_mask = 0x01;
00169             while (ROM_bit_index<=64) {
00170                 Bit_A = onewire_bit_in(pin);
00171                 Bit_B = onewire_bit_in(pin);
00172                 if (Bit_A & Bit_B) {
00173                     descrepancy_marker = 0; // data read error, this should never happen
00174                     ROM_bit_index = 0xFF;
00175                 } else {
00176                     if (Bit_A | Bit_B) {
00177                         // Set ROM bit to Bit_A
00178                         if (Bit_A) {
00179                             DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
00180                         } else {
00181                             DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
00182                         }
00183                     } else {
00184                         // both bits A and B are low, so there are two or more devices present
00185                         if ( ROM_bit_index == DS1820_last_descrepancy ) {
00186                             DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
00187                         } else {
00188                             if ( ROM_bit_index > DS1820_last_descrepancy ) {
00189                                 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
00190                                 descrepancy_marker = ROM_bit_index;
00191                             } else {
00192                                 if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
00193                                     descrepancy_marker = ROM_bit_index;
00194                             }
00195                         }
00196                     }
00197                     onewire_bit_out (pin, DS1820_search_ROM[byte_counter] & bit_mask);
00198                     ROM_bit_index++;
00199                     if (bit_mask & 0x80) {
00200                         byte_counter++;
00201                         bit_mask = 0x01;
00202                     } else {
00203                         bit_mask = bit_mask << 1;
00204                     }
00205                 }
00206             }
00207             DS1820_last_descrepancy = descrepancy_marker;
00208             if (ROM_bit_index != 0xFF) {
00209                 int i = 1;
00210                 node *list_container;
00211                 while(1) {
00212                     list_container = probes.pop(i);
00213                     if (list_container == NULL) {                             //End of list, or empty list
00214                         if (ROM_checksum_error(DS1820_search_ROM)) {          // Check the CRC
00215                             return false;
00216                         }
00217                         for(byte_counter=0;byte_counter<8;byte_counter++)
00218                             ROM_address[byte_counter] = DS1820_search_ROM[byte_counter];
00219                         return true;
00220                     } else {                    //Otherwise, check if ROM is already known
00221                         bool equal = true;
00222                         DS1820 *pointer = (DS1820*) list_container->data;
00223                         char *ROM_compare = pointer->_ROM;
00224                         
00225                         for(byte_counter=0;byte_counter<8;byte_counter++) {
00226                             if ( ROM_compare[byte_counter] != DS1820_search_ROM[byte_counter])
00227                                 equal = false;
00228                         }
00229                         if (equal)
00230                             break;
00231                         else
00232                             i++;
00233                     }
00234                 }                        
00235             }
00236         }
00237         if (DS1820_last_descrepancy == 0)
00238             DS1820_done_flag = true;
00239     }
00240     return return_value;
00241 }
00242  
00243 void DS1820::match_ROM() {
00244 // Used to select a specific device
00245     int i;
00246     onewire_reset(&this->_datapin);
00247     onewire_byte_out( 0x55);  //Match ROM command
00248     for (i=0;i<8;i++) {
00249         onewire_byte_out(_ROM[i]);
00250     }
00251 }
00252  
00253 void DS1820::skip_ROM() {
00254     onewire_reset(&this->_datapin);
00255     onewire_byte_out(0xCC);   // Skip ROM command
00256 }
00257  
00258 bool DS1820::ROM_checksum_error(char *_ROM_address) {
00259     char _CRC=0x00;
00260     int i;
00261     for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
00262         _CRC = CRC_byte(_CRC, _ROM_address[i]);
00263     // After 7 bytes CRC should equal the 8th byte (ROM CRC)
00264     return (_CRC!=_ROM_address[7]); // will return true if there is a CRC checksum mis-match         
00265 }
00266  
00267 bool DS1820::RAM_checksum_error() {
00268     char _CRC=0x00;
00269     int i;
00270     for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
00271         _CRC = CRC_byte(_CRC, RAM[i]);
00272     // After 8 bytes CRC should equal the 9th byte (RAM CRC)
00273     return (_CRC!=RAM[8]); // will return true if there is a CRC checksum mis-match        
00274 }
00275  
00276 char DS1820::CRC_byte (char _CRC, char byte ) {
00277     int j;
00278     for(j=0;j<8;j++) {
00279         if ((byte & 0x01 ) ^ (_CRC & 0x01)) {
00280             // DATA ^ LSB CRC = 1
00281             _CRC = _CRC>>1;
00282             // Set the MSB to 1
00283             _CRC = _CRC | 0x80;
00284             // Check bit 3
00285             if (_CRC & 0x04) {
00286                 _CRC = _CRC & 0xFB; // Bit 3 is set, so clear it
00287             } else {
00288                 _CRC = _CRC | 0x04; // Bit 3 is clear, so set it
00289             }
00290             // Check bit 4
00291             if (_CRC & 0x08) {
00292                 _CRC = _CRC & 0xF7; // Bit 4 is set, so clear it
00293             } else {
00294                 _CRC = _CRC | 0x08; // Bit 4 is clear, so set it
00295             }
00296         } else {
00297             // DATA ^ LSB CRC = 0
00298             _CRC = _CRC>>1;
00299             // clear MSB
00300             _CRC = _CRC & 0x7F;
00301             // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
00302         }
00303         byte = byte>>1;
00304     }
00305 return _CRC;
00306 }
00307  
00308 int DS1820::convertTemperature(bool wait, devices device) {
00309     // Convert temperature into scratchpad RAM for all devices at once
00310     int delay_time = 750; // Default delay time
00311     char resolution;
00312     if (device==all_devices)
00313         skip_ROM();          // Skip ROM command, will convert for ALL devices
00314     else {
00315         match_ROM();
00316         if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
00317             resolution = RAM[4] & 0x60;
00318             if (resolution == 0x00) // 9 bits
00319                 delay_time = 94;
00320             if (resolution == 0x20) // 10 bits
00321                 delay_time = 188;
00322             if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
00323                 delay_time = 375;
00324         }
00325     }
00326     
00327     onewire_byte_out( 0x44);  // perform temperature conversion
00328     if (_parasite_power) {
00329         if (_power_mosfet) {
00330             _parasitepin = _power_polarity;     // Parasite power strong pullup
00331             wait_ms(delay_time);
00332             _parasitepin = !_power_polarity;
00333             delay_time = 0;
00334         } else {
00335             _datapin.output();
00336             _datapin.write(1);
00337             wait_ms(delay_time);
00338             _datapin.input();
00339         }
00340     } else {
00341         if (wait) {
00342             wait_ms(delay_time);
00343             delay_time = 0;
00344         }
00345     }
00346     return delay_time;
00347 }
00348  
00349 void DS1820::read_RAM() {
00350     // This will copy the DS1820's 9 bytes of RAM data
00351     // into the objects RAM array. Functions that use
00352     // RAM values will automaticly call this procedure.
00353     int i;
00354     match_ROM();             // Select this device
00355     onewire_byte_out( 0xBE);   //Read Scratchpad command
00356     for(i=0;i<9;i++) {
00357         RAM[i] = onewire_byte_in();
00358     }
00359 //    if (!RAM_checksum_error())
00360 //       crcerr = 1;
00361 }
00362 
00363 bool DS1820::setResolution(unsigned int resolution) {
00364     bool answer = false;
00365     resolution = resolution - 9;
00366     if (resolution < 4) {
00367         resolution = resolution<<5; // align the bits
00368         RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
00369         write_scratchpad ((RAM[2]<<8) + RAM[3]);
00370 //        store_scratchpad (DS1820::this_device); // Need to test if this is required
00371         answer = true;
00372     }
00373     return answer;
00374 }
00375  
00376 void DS1820::write_scratchpad(int data) {
00377     RAM[3] = data;
00378     RAM[2] = data>>8;
00379     match_ROM();
00380     onewire_byte_out(0x4E);   // Copy scratchpad into DS1820 ram memory
00381     onewire_byte_out(RAM[2]); // T(H)
00382     onewire_byte_out(RAM[3]); // T(L)
00383     if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
00384         onewire_byte_out(RAM[4]); // Configuration register
00385     }
00386 }
00387  
00388 float DS1820::temperature(char scale) {
00389 // The data specs state that count_per_degree should be 0x10 (16), I found my devices
00390 // to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
00391 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
00392 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
00393 // deg C or F scales.
00394     float answer, remaining_count, count_per_degree;
00395     int reading;
00396     read_RAM();
00397     if (RAM_checksum_error())
00398         // Indicate we got a CRC error
00399         answer = invalid_conversion;
00400     else {
00401         reading = (RAM[1] << 8) + RAM[0];
00402         if (reading & 0x8000) { // negative degrees C
00403             reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
00404         }
00405         answer = reading +0.0; // convert to floating point
00406         if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
00407             answer = answer / 16.0f;
00408         }
00409         else {
00410             remaining_count = RAM[6];
00411             count_per_degree = RAM[7];
00412             answer = floor(answer/2.0f) - 0.25f + (count_per_degree - remaining_count) / count_per_degree;
00413         }
00414         if (scale=='F' or scale=='f')
00415             // Convert to deg F
00416             answer = answer * 9.0f / 5.0f + 32.0f;
00417     }
00418     return answer;
00419 }
00420  
00421 bool DS1820::read_power_supply(devices device) {
00422 // This will return true if the device (or all devices) are Vcc powered
00423 // This will return false if the device (or ANY device) is parasite powered
00424     if (device==all_devices)
00425         skip_ROM();          // Skip ROM command, will poll for any device using parasite power
00426     else
00427         match_ROM();
00428     onewire_byte_out(0xB4);   // Read power supply command
00429     return onewire_bit_in(&this->_datapin);
00430 }
00431 
00432 bool DS1820::isValid() {
00433     return valid;
00434 }
00435