SPMA057D January   2018  – June 2022 TM4C1290NCPDT , TM4C1290NCPDT , TM4C1290NCZAD , TM4C1290NCZAD , TM4C1292NCPDT , TM4C1292NCPDT , TM4C1292NCZAD , TM4C1292NCZAD , TM4C1294KCPDT , TM4C1294KCPDT , TM4C1294NCPDT , TM4C1294NCPDT , TM4C1294NCZAD , TM4C1294NCZAD , TM4C1297NCZAD , TM4C1297NCZAD , TM4C1299KCZAD , TM4C1299KCZAD , TM4C1299NCZAD , TM4C1299NCZAD , TM4C129CNCPDT , TM4C129CNCPDT , TM4C129CNCZAD , TM4C129CNCZAD , TM4C129DNCPDT , TM4C129DNCPDT , TM4C129DNCZAD , TM4C129DNCZAD , TM4C129EKCPDT , TM4C129EKCPDT , TM4C129ENCPDT , TM4C129ENCPDT , TM4C129ENCZAD , TM4C129ENCZAD , TM4C129LNCZAD , TM4C129LNCZAD , TM4C129XKCZAD , TM4C129XKCZAD , TM4C129XNCZAD , TM4C129XNCZAD , TMP1826 , TMP1826 , TMP1827 , TMP1827

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction to 1-Wire
    1. 1.1 Bus Requirements
    2. 1.2 Powering
  4. 2Functional Description
    1. 2.1 Signaling on 1-Wire
    2. 2.2 Address Format of the 1-Wire Device
    3. 2.3 Typical Communication Flow on the 1-Wire Bus
  5. 3Functions Available in TivaWare for C Series for 1-Wire Module
  6. 4Enumeration
    1. 4.1 Legacy Search Algorithm
      1. 4.1.1 Steps of the 3-Bit Search Algorithm
    2. 4.2 Fast Search Algorithm
  7. 5Summary
  8. 6References
  9. 7Revision History

4.2 Fast Search Algorithm

The fast search algorithm uses the TMP1826 devices to arbitrate. The host issues a SKIP ADDRESS command and writes the configuration register-2 bits for ARB_MODE as 11b. After performing the last step it issues a SEARCH ADDRESS command and reads 1-bit of the device address. All devices on the bus transmit their address as either logic 1 or 0 and monitor the SDQ line to read back what they have transmitted. Since the logic 0 is a dominant value, any device that sent logic 1 will lose the bus and no longer participate in the current iteration of the address search operation.

The host then reads the next 1-bit of the device address from the devices that have won the bus arbitration. This process continues till only one device successfully sends its 64-bit device address at which point the device sets a success flag in its status register. The host then sends another SEARCH ADDRESS command and all the devices except the one which have been enumerated rejoin the process of address enumeration.

The fast search algorithm compared to the legacy search algorithm from older 1-wire devices is 3 times faster and saves the memory and processing cost of implementing a binary tree search. For more details on the method described and re-enumeration, see the TMP1826 Single-Wire, ±0.3°C Accurate Temperature Sensor With 2-Kbit EEPROM Data Sheet.