Instruction Manual

DS18S20
11 of 21
DS18S20 FUNCTION COMMAND SET Table 4
Command Description Protocol
1-Wire Bus Activity
After Command is Issued Notes
TEMPERATURE CONVERSION COMMANDS
Convert T Initiates temperature
conversion.
44h DS18S20 transmits conversion
status to master (not applicable
for parasite-powered DS18S20s).
1
MEMORY COMMANDS
Read Scratchpad Reads the entire scratchpad
including the CRC byte.
BEh DS18S20 transmits up to 9 data
bytes to master.
2
Write Scratchpad Writes data into scratchpad
bytes 2 and 3 (T
H
and T
L
).
4Eh Master transmits 2 data bytes to
DS18S20.
3
Copy Scratchpad Copies T
H
and T
L
data from
the scratchpad to EEPROM.
48h None 1
Recall E
2
Recalls T
H
and T
L
data from
EEPROM to the scratchpad.
B8h DS18S20 transmits recall status
to master.
Read Power
Supply
Signals DS18S20 power
supply mode to the master.
B4h DS18S20 transmits supply status
to master.
NOTES:
1. For parasite-powered DS18S20s, the master must enable a strong pullup on the 1-wire bus during
temperature conversions and copies from the scratchpad to EEPROM. No other bus activity may take
place during this time.
2. The master can interrupt the transmission of data at any time by issuing a reset.
3. Both bytes must be written before a reset is issued.