Datasheet

Figure 14. DS18B20 Function Commands Flowchart
MASTER Tx
FUNCTION COMMAND
44
h CONVERT
TEMPERATURE ?
N
Y
PARASITE
POWER ?
DS18B20 BEGINS
CONVERSION
DEVICE
CONVERTING
TEMPERATURE ?
Y
MASTER
Rx “0s”
MASTER
Rx “1
s”
N
MASTER ENABLES STRONG
PULL-UP ON DQ
DS18B20 CONVERTS
TEMPERATURE
MASTER DISABLES
STRONG PULLUP
Y
N
B4h READ
POWER SUPPLY ?
Y
PARASITE
POWER
?
Y
N
MASTER
Rx “1s”
MASTER
Rx “0s”
N
B8h
RECALL E
2
?
Y
MASTER BEGINS
DATA RECALL FROM
E
2
PROM
DEVICE BUSY
RECALLING
DATA ?
Y
MASTER
Rx “0s”
MASTER
Rx “
1
s”
N
N
BEh READ
SCRATCHPAD ?
N
MASTER Rx DATA
BYTE FROM
SCRATCHPAD
MASTER Tx
RESET
?
HAVE 8 BYTES
BEEN READ ?
MASTER Rx
SCRATCHPAD CRC
BYTE
N
Y
N
Y
MASTER Tx T
H
BYTE TO
SCRATCHPAD
MASTER Tx T
L
BYTE TO
SCRATCHPAD
MASTER TX CONFIG. BYTE
TO SCRATCHPAD
4
Eh WRITE
SCRATCHPAD ?
N
Y
48
h COPY
SCRATCHPAD ?
N
Y
PARASITE
POWER ?
COPY IN
PROGRESS ?
Y
MASTER
Rx “0s”
MASTER
Rx “1s”
N
MASTER ENABLES STRONG
PULL
-UP ON DQ
DATA COPIED FROM
SCRATCHPAD TO EEPROM
MASTER DISABLES
STRONG PULLUP
Y
N
RETURN TO INITIALIZATION
SEQUENCE (FIGURE 13)
FOR NEXT TRANSACTION
Y
DS18B20 Programmable Resolution
1-Wire Digital Thermometer
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