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Test 1-wire , working wtih parasite power and few sensors with mixed power supply.
onewire.cpp
- Committer:
- macraj
- Date:
- 2010-05-10
- Revision:
- 0:1197076b78f4
File content as of revision 0:1197076b78f4:
#include "mbed.h" #include "onewire.h" #include "crc8.h" // DS18B20 converted to run on mbed DigitalInOut ow_pin(ONEWIRE_PIN); BYTE ow_reset(void) { // reset. Should improve to act as a presence pulse BYTE err; ow_pin.output(); ow_pin = 0; // bring low for 500 us wait_us(500); ow_pin.input(); wait_us(60); err = ow_pin; wait_us(240); if ( ow_pin == 0 ) { // short circuit err = OW_SHORT_CIRCUIT; #ifdef DEBUG printf("Error. Short circut!!!\n"); #endif } return err; } BYTE ow_bit_io( BYTE b ) { ow_pin.output(); // drive bus low ow_pin = 0; wait_us(1); // Recovery-Time wuffwuff was 1 //ow_pin.input(); if ( b ) ow_pin.input(); // if bit is 1 set bus high (by ext. pull-up) // delay was 15uS-1 see comment above wait_us(15-1); // ???ow_pin.input(); if ( ow_pin == 0 ) b = 0; // sample at end of read-timeslot wait_us(60-15); ow_pin.input(); return b; } BYTE ow_byte_wr( uint8_t b ) { uint8_t i = 8, j; do { j = ow_bit_io( b & 1 ); b >>= 1; if ( j ) b |= 0x80; } while ( --i ); return b; } uint8_t ow_byte_rd( void ) { // read by sending 0xff (a dontcare?) return ow_byte_wr( 0xFF ); } BYTE ow_rom_search( BYTE diff, BYTE *id ) { BYTE i, j, next_diff; BYTE b; if ( ow_reset() ) return OW_PRESENCE_ERR; // error, no device found ow_byte_wr( OW_SEARCH_ROM ); // ROM search command next_diff = OW_LAST_DEVICE; // unchanged on last device i = OW_ROMCODE_SIZE * 8; // 8 bytes do { j = 8; // 8 bits do { b = ow_bit_io( 1 ); // read bit if ( ow_bit_io( 1 ) ) { // read complement bit if ( b ) // 11 return OW_DATA_ERR; // data error } else { if ( !b ) { // 00 = 2 devices if ( diff > i || ((*id & 1) && diff != i) ) { b = 1; // now 1 next_diff = i; // next pass 0 } } } ow_bit_io( b ); // write bit *id >>= 1; if ( b ) *id |= 0x80; // store bit i--; } while ( --j ); id++; // next byte } while ( i ); return next_diff; // to continue search } void ow_command( BYTE command, BYTE *id ) { BYTE i; ow_reset(); if ( id ) { ow_byte_wr( OW_MATCH_ROM ); // to a single device i = OW_ROMCODE_SIZE; do { ow_byte_wr( *id ); id++; } while ( --i ); } else { ow_byte_wr( OW_SKIP_ROM ); // to all devices } ow_byte_wr( command ); } void ow_parasite_enable(void) { ow_pin.output(); ow_pin = 1; } void ow_parasite_disable(void) { ow_pin.input(); } /* find DS18X20 Sensors on 1-Wire-Bus input/ouput: diff is the result of the last rom-search output: id is the rom-code of the sensor found */ void DS18X20_find_sensor(BYTE *diff, BYTE id[]) { for (;;) { *diff = ow_rom_search( *diff, &id[0] ); if ( *diff==OW_PRESENCE_ERR || *diff==OW_DATA_ERR || *diff == OW_LAST_DEVICE ) return; if ( id[0] == DS18B20_ID || id[0] == DS18S20_ID ) return; } } /* get power status of DS18x20 input : id = rom_code returns: DS18X20_POWER_EXTERN or DS18X20_POWER_PARASITE */ BYTE DS18X20_get_power_status(uint8_t id[]) { uint8_t pstat; ow_reset(); ow_command(DS18X20_READ_POWER_SUPPLY, id); pstat=ow_bit_io(1); // pstat 0=is parasite/ !=0 ext. powered ow_reset(); return (pstat) ? DS18X20_POWER_EXTERN:DS18X20_POWER_PARASITE; } void DS18X20_show_id_uart( BYTE *id, size_t n ) { size_t i; for ( i = 0; i < n; i++ ) { if ( i == 0 ) printf( "FC: " ); else if ( i == n-1 ) printf( "CRC: " ); if ( i == 1 ) printf( " SN: " ); printf("%X ",id[i]); if ( i == 0 ) { if ( id[0] == DS18S20_ID ) printf("(18S)"); else if ( id[0] == DS18B20_ID ) printf("(18B)"); else printf("( ? )"); } } if ( crc8( id, OW_ROMCODE_SIZE) ) printf( " CRC FAIL\n " ); else printf( " CRC O.K.\n" ); } /* start measurement (CONVERT_T) for all sensors if input id==NULL or for single sensor. then id is the rom-code */ uint8_t DS18X20_start_meas( uint8_t with_power_extern, uint8_t id[]) { ow_reset(); //** if ( ow_pin ) { // only send if bus is "idle" = high ow_command( DS18X20_CONVERT_T, id ); if (with_power_extern != DS18X20_POWER_EXTERN) ow_parasite_enable(); return DS18X20_OK; } else { #ifdef DEBUG printf( "DS18X20_start_meas: Short Circuit !\n" ); #endif return DS18X20_START_FAIL; } } /* reads temperature (scratchpad) of sensor with rom-code id output: subzero==1 if temp.<0, cel: full celsius, mcel: frac in millicelsius*0.1 i.e.: subzero=1, cel=18, millicel=5000 = -18,5000°C */ uint8_t DS18X20_read_meas(uint8_t id[], uint8_t *subzero, uint8_t *cel, uint8_t *cel_frac_bits) { uint8_t i; uint8_t sp[DS18X20_SP_SIZE]; ow_reset(); //** ow_command(DS18X20_READ, id); for ( i=0 ; i< DS18X20_SP_SIZE; i++ ) sp[i]=ow_byte_rd(); if ( crc8( &sp[0], DS18X20_SP_SIZE ) ) return DS18X20_ERROR_CRC; DS18X20_meas_to_cel(id[0], sp, subzero, cel, cel_frac_bits); return DS18X20_OK; } /* convert raw value from DS18x20 to Celsius input is: - familycode fc (0x10/0x28 see header) - scratchpad-buffer output is: - cel full celsius - fractions of celsius in millicelsius*(10^-1)/625 (the 4 LS-Bits) - subzero =0 positiv / 1 negativ always returns DS18X20_OK TODO invalid-values detection (but should be covered by CRC) */ uint8_t DS18X20_meas_to_cel( uint8_t fc, uint8_t *sp, uint8_t* subzero, uint8_t* cel, uint8_t* cel_frac_bits) { uint16_t meas; uint8_t i; meas = sp[0]; // LSB meas |= ((uint16_t)sp[1])<<8; // MSB //meas = 0xff5e; meas = 0xfe6f; // only work on 12bit-base if ( fc == DS18S20_ID ) { // 9 -> 12 bit if 18S20 /* Extended measurements for DS18S20 contributed by Carsten Foss */ meas &= (uint16_t) 0xfffe; // Discard LSB , needed for later extended precicion calc meas <<= 3; // Convert to 12-bit , now degrees are in 1/16 degrees units meas += (16 - sp[6]) - 4; // Add the compensation , and remember to subtract 0.25 degree (4/16) } // check for negative if ( meas & 0x8000 ) { *subzero=1; // mark negative meas ^= 0xffff; // convert to positive => (twos complement)++ meas++; } else *subzero=0; // clear undefined bits for B != 12bit if ( fc == DS18B20_ID ) { // check resolution 18B20 i = sp[DS18B20_CONF_REG]; if ( (i & DS18B20_12_BIT) == DS18B20_12_BIT ) ; else if ( (i & DS18B20_11_BIT) == DS18B20_11_BIT ) meas &= ~(DS18B20_11_BIT_UNDF); else if ( (i & DS18B20_10_BIT) == DS18B20_10_BIT ) meas &= ~(DS18B20_10_BIT_UNDF); else { // if ( (i & DS18B20_9_BIT) == DS18B20_9_BIT ) { meas &= ~(DS18B20_9_BIT_UNDF); } } *cel = (uint8_t)(meas >> 4); *cel_frac_bits = (uint8_t)(meas & 0x000F); return DS18X20_OK; } /* converts to decicelsius input is ouput from meas_to_cel returns absolute value of temperatur in decicelsius i.e.: sz=0, c=28, frac=15 returns 289 (=28.9°C) 0 0 0 1 625 625 1 2 1250 250 3 1875 875 3 4 2500 500 4 5 3125 125 6 3750 750 6 7 4375 375 8 5000 0 9 5625 625 9 10 6250 250 11 6875 875 11 12 7500 500 12 13 8125 125 14 8750 750 14 15 9375 375 */ uint16_t DS18X20_temp_to_decicel(uint8_t subzero, uint8_t cel, uint8_t cel_frac_bits) { uint16_t h; uint8_t i; uint8_t need_rounding[] = { 1, 3, 4, 6, 9, 11, 12, 14 }; h = cel_frac_bits*DS18X20_FRACCONV/1000; h += cel*10; if (!subzero) { for (i=0; i<sizeof(need_rounding); i++) { if ( cel_frac_bits == need_rounding[i] ) { h++; break; } } } return h; } /* compare temperature values (full celsius only) returns -1 if param-pair1 < param-pair2 0 if == 1 if > */ int8_t DS18X20_temp_cmp(uint8_t subzero1, uint16_t cel1, uint8_t subzero2, uint16_t cel2) { int16_t t1 = (subzero1) ? (cel1*(-1)) : (cel1); int16_t t2 = (subzero2) ? (cel2*(-1)) : (cel2); if (t1<t2) return -1; if (t1>t2) return 1; return 0; } void OneWireOutByte(unsigned char d) { // output byte d (least sig bit first). for (int n=8; n!=0; n--) { if ((d & 0x01) == 1) { // test least sig bit ow_pin.output(); ow_pin = 0; wait_us(5); ow_pin.input(); wait_us(80); } else { ow_pin.output(); ow_pin = 0; wait_us(80); ow_pin.input(); } d=d>>1; // now the next bit is in the least sig bit position. } } unsigned char OneWireInByte() { // read byte, least sig byte first unsigned char d = 0, b; for (int n=0; n<8; n++) { ow_pin.output(); ow_pin = 0; wait_us(5); ow_pin.input(); wait_us(5); b =ow_pin; wait_us(50); d = (d >> 1) | (b << 7); // shift d to right and insert b in most sig bit position } return d; }