DS18B20

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Related Application Notes

The following Application Notes can be applied to the DS18B20. These notes can be obtained from the

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

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.