One Wire Example striped to find sensors only builds using MBED 2 Library
Dependencies: mbed
onewire.cpp
- Committer:
- Roietronics
- Date:
- 2017-06-05
- Revision:
- 0:486c7ab9114b
File content as of revision 0:486c7ab9114b:
/** * @file onewire.c * @brief library 1-Wire(www.maxim-ic.com) * @author Maciej Rajtar (Published 10 May 2010 www.mbed.org) * @author Frederic BLANC */ #include "mbed.h" #include "onewire.h" #include "DS2450.h" #include "DS18X20.h" #include "crc8.h" DigitalInOut ow_pin(ONEWIRE_PIN); /** * @brief PUL-UP bus OW * @return OW_OK * @date 20/06/2011 */ uint8_t ow_PullUp(void) { ow_pin.mode(PullUp); //PULL-UP bus OW return OW_OK; } /** * @brief search_sensors * @param [out] nSensors number of device onewire * @param [out] gSensorIDs[][] array of id romcode * @return OW_OK or OW_PRESENCE_ERR or OW_DATA_ERR * @date 20/06/2011 */ uint8_t search_sensors(uint8_t *nSensors,uint8_t *gSensorIDs ) { uint8_t i; uint8_t id[OW_ROMCODE_SIZE]; uint8_t diff; printf( "Scanning Bus\n" ); diff = OW_SEARCH_FIRST; for (*nSensors = 0 ; (diff != OW_LAST_DEVICE) && (*nSensors < MAXSENSORS) ;++(*nSensors) ) { ow_find_sensor( &diff, &id[0] ); if ( diff == OW_PRESENCE_ERR ) { printf( "No Sensor found\n" ); return diff; } if ( diff == OW_DATA_ERR ) { printf( "Bus Error\n" ); return diff; } for (i=0;i<OW_ROMCODE_SIZE;i++) gSensorIDs[(*nSensors)*OW_ROMCODE_SIZE+i]=id[i]; } return OW_OK; } /** * @brief show_id * @param [in] id[] = rom_code * @param [in] n number of id[n] * @param [out] text id * @return OW_OK or OW_ERROR_CRC * @date 20/06/2011 */ uint8_t ow_show_id( uint8_t id[], size_t n ,char *text) { size_t i; char hex[4]; sprintf(text,""); for ( i = 0; i < n; i++ ) { if ( i == 0 ) strcat(text, " FC: " ); else if ( i == n-1 ) strcat(text, "CRC: " ); if ( i == 1 ) strcat(text, " SN: " ); sprintf(hex,"%2.2X ",id[i]); strcat(text,hex); if ( i == 0 ) { if ( id[0] == DS18S20_ID ) strcat(text,"(18S)"); else if ( id[0] == DS18B20_ID ) strcat(text,"(18B)"); else if ( id[0] == DS2450_ID ) strcat(text,"(ADC)"); else strcat(text,"( ? )"); } } if ( crc8( id, OW_ROMCODE_SIZE) ) return OW_ERROR_CRC; return OW_OK; } /** * @brief test pin onewire bus * @return etat pin ow * @date 20/06/2011 */ uint8_t ow_test_pin (void){ if (ow_pin) return 1; return 0; } /** * @brief onewire reset bus * @return pin ow or OW_SHORT_CIRCUIT * @date 20/06/2011 */ uint8_t ow_reset(void) { // reset. Should improve to act as a presence pulse uint8_t 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; } return err; } /** * @brief read write onewire * @param [in/out] b data * @return data * @date 20/06/2011 */ uint8_t ow_bit_io( uint8_t b ) { ow_pin.output(); // drive bus low ow_pin = 0; wait_us(1); // Recovery-Time wuffwuff was 1 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); if ( ow_pin == 0 ) b = 0; // sample at end of read-timeslot wait_us(60-15); ow_pin.input(); return b; } /** * @brief byte write on onewire * @param [in] b data * @return data * @date 20/06/2011 */ uint8_t 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; } /** * @brief byte read on onewire * @param [in] uint8_t b * @return * @date 20/06/2011 */ uint8_t ow_byte_rd( void ) { // read by sending 0xff (a dontcare?) return ow_byte_wr( 0xFF ); } /** * @brief search romcode * @param [in] uint8_t diff * @param [out] id romcode * @return next_diff or OW_LAST_DEVICE or OW_DATA_ERR or OW_PRESENCE_ERR * @date 20/06/2011 */ uint8_t ow_rom_search( uint8_t diff, uint8_t id[] ) { uint8_t i, j, next_diff; uint8_t 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 } /** * @brief write command * @param [in] command * @param [in] id romcode * @date 20/06/2011 */ uint8_t ow_command( uint8_t command, uint8_t id[] ) { uint8_t 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 ); return 0; } /** * @brief parasite enable * @date 20/06/2011 */ uint8_t ow_parasite_enable(void) { ow_pin.output(); ow_pin = 1; return 0; } /** * @brief parasite disable * @date 20/06/2011 */ uint8_t ow_parasite_disable(void) { ow_pin.input(); return 0; } /** * @brief find Sensors on 1-Wire-Bus * @param [in/out] diff is the result of the last rom-search * @param [out] is the rom-code of the sensor found * @return OW_OK or OW_ERROR */ uint8_t ow_find_sensor(uint8_t *diff, uint8_t id[]) { for (;;) { *diff = ow_rom_search( *diff, &id[0] ); if ( *diff==OW_PRESENCE_ERR) return OW_ERROR; if ( *diff==OW_DATA_ERR ) return OW_ERROR; if ( *diff == OW_LAST_DEVICE ) return OW_OK ; if ( id[0] == DS18B20_ID || id[0] == DS18S20_ID ) return OW_OK ; if ( id[0] == DS2450_ID ) return OW_OK ; } } /** * @brief output byte d (least sig bit first) * @param [in] d output byte (least sig bit first) * @return OW_OK */ uint8_t OneWireOutByte(uint8_t 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. } return OW_OK; } /** * @brief read byte, least sig byte first * @return byte, least sig byte first */ uint8_t OneWireInByte(void) { // read byte, least sig byte first uint8_t 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; }