Data Sheet

DS18B20
22 of 27
Related Application Notes
The following Application Notes can be applied to the DS18B20. These notes can be obtained from the
Dallas Semiconductor “Application Note Book,” via our website at http://www.dalsemi.com/.
Application Note 27: “Understanding and Using Cyclic Redundancy Checks with Dallas Semiconductor
Touch Memory Product”
Application Note 55: “Extending the Contact Range of Touch Memories”
Application Note 74: “Reading and Writing Touch Memories via Serial Interfaces”
Application Note 104: “Minimalist Temperature Control Demo”
Application Note 106: “Complex MicroLANs”
Application Note 108: “MicroLAN - In the Long Run”
Sample 1-Wire subroutines that can be used in conjunction with AN74 can be downloaded from the
website or our Anonymous FTP Site.
MEMORY FUNCTION EXAMPLE Table 5
Example: Bus Master initiates temperature conversion, then reads temperature (parasite power assumed).
MASTER MODE DATA (LSB FIRST) COMMENTS
TX Reset Reset pulse (480-960 µs).
RX Presence Presence pulse.
TX 55h Issue “Match ROM” command.
TX <64-bit ROM code> Issue address for DS18B20.
TX 44h Issue “ Convert T” command.
TX <I/O LINE HIGH> I/O line is held high for at least a period of time greater
than t
conv
by bus master to allow conversion to complete.
TX Reset Reset pulse.
RX Presence Presence pulse.
TX 55h Issue “Match ROM” command.
TX <64-bit ROM code> Issue address for DS18B20.
TX BEh Issue “Read Scratchpad” command.
RX <9 data bytes> Read entire scratchpad plus CRC; the master now
recalculates the CRC of the eight data bytes received
from the scratchpad, compares the CRC calculated and
the CRC read. If they match, the master continues; if
not, this read operation is repeated.
TX Reset Reset pulse.
RX Presence Presence pulse, done.