DS1820S Ver la hoja de datos (PDF) - Dallas Semiconductor -> Maxim Integrated
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DS1820S Datasheet PDF : 27 Pages
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DS1820
INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” Figure 11
VCC
1–WIRE
BUS
GND
Master TX “reset pulse”
480 µs minimum
960 µs maximum
DS1820
waits
15 - 60 µs
Master RX
480 µs minimum
DS1820 TX
“presence pulse”
60 - 240 µs
LINE TYPE LEGEND:
Bus master active low
Both bus master and
DS1820 active low
DS1820 active low
Resistor pull–up
DS1820 COMMAND SET Table 2
INSTRUCTION
DESCRIPTION
PROTOCOL
1–WIRE BUS
AFTER ISSUING
PROTOCOL
TEMPERATURE CONVERSION COMMANDS
Convert T
Initiates temperature conversion.
44h
<read temperature
busy status>
MEMORY COMMANDS
Read Scratchpad
Reads bytes from scratchpad and
reads CRC byte.
BEh
<read data up to 9
bytes>
Write Scratchpad
Writes bytes into scratchpad at
addresses 2 and 3 (TH and TL
temperature triggers).
4Eh
<write data into 2
bytes at addr. 2 and
addr. 3>
Copy Scratchpad
Copies scratchpad into nonvolatile
memory (addresses 2 and 3 only).
48h
<read copy status>
Recall E2
Recalls values stored in nonvolatile
B8h
<read temperature
memory into scratchpad (tempera-
busy status>
ture triggers).
Read Power Supply Signals the mode of DS1820
power supply to the master.
B4h
<read supply status>
NOTES
1
2
NOTES:
1. Temperature conversion takes up to 500 ms. After receiving the Convert T protocol, if the part does not
receive power from the VDD pin, the I/O line for the DS1820 must be held high for at least 500 ms to provide
power during the conversion process. As such, no other activity may take place on the 1–Wire bus for at least
this period after a Convert T command has been issued.
2. After receiving the Copy Scratchpad protocol, if the part does not receive power from the VDD pin, the I/O line
for the DS1820 must be held high for at least 10 ms to provide power during the copy process. As such, no
other activity may take place on the 1–Wire bus for at least this period after a Copy Scratchpad command has
been issued.
030598 16/27
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