Datasheet

Figure 16. ROM Commands Flowchart
CCh
SKIP ROM
COMMAND
MASTER Tx RESET PULSE
DS18S20 Tx PRESENCE PULSE
MASTER Tx ROM COMMAND
33h
READ ROM
COMMAND
55h
MATCH ROM
COMMAND
F0h
SEARCH ROM
COMMAND
ECh
ALARM SEARCH
COMMAND
MASTER Tx
BIT 0
DS18
S20 Tx BIT 0
DS18S20 Tx BIT 0
MASTER Tx BIT 0
BIT 0
MATCH?
MASTER Tx
BIT 1
BIT 1
MATCH?
BIT 63
MATCH?
MASTER Tx
BIT 63
N
Y
Y Y
N
N
Y
Y
Y
DS18S20 Tx BIT 1
MASTER Tx BIT 1
DS18S20 T BIT 63
DS18S20 Tx BIT 63
MASTER Tx BIT 63
BIT 0
MATCH?
BIT 1
MATCH?
BIT 63
MATCH?
N
Y
DS18
S20 Tx
FAMILY CODE
1 BYTE
DS18S20 Tx
SERIAL NUMBER
6 BYTES
DS18S20 Tx
CRC BYTE
DS18S20 Tx BIT 0
DS18S20 Tx BIT 0
MASTER Tx BIT 0
DEVICE(S)
WITH ALARM
FLAG SET?
INITIALIZATION
SEQUENCE
MASTER Tx FUNCTION
COMMAND (FIGURE 17)
N
Y
N N
Y
Y
N
Y
N
N
N
Y
N
DS18S20 Tx BIT 1
DS18S20 High-Precision 1-Wire Digital Thermometer
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