DS1822-PAR_07 DALLAS [Dallas Semiconductor], DS1822-PAR_07 Datasheet - Page 16

• Manufacturer Part Number: DS1822-PAR_07
• Description: Econo 1-Wire Parasite-Power Digital Thermometer
• Manufacturer: DALLAS [Dallas Semiconductor]

DS1822-PAR OPERATION EXAMPLE 1
In this example there are multiple DS1822-PARs on the bus. The bus master initiates a temperature
conversion in a specific DS1822-PAR and then reads its scratchpad and recalculates the CRC to verify
the data.
DS1822-PAR OPERATION EXAMPLE 2
In this example there is only one DS1822-PAR on the bus. The master writes to the T
configuration registers in the DS1822-PAR scratchpad and then reads the scratchpad and recalculates the
CRC to verify the data. The master then copies the scratchpad contents to EEPROM.
MASTER MODE
MASTER MODE
TX
RX
TX
TX
TX
TX
TX
RX
TX
TX
TX
RX
TX
RX
TX
TX
TX
TX
RX
TX
TX
RX
TX
RX
TX
TX
TX
DATA (LSB FIRST)
DQ line held high by
DATA (LSB FIRST)
DQ line held high by
64-bit ROM code
64-bit ROM code
strong pullup
3 data bytes
9 data bytes
strong pullup
9 data bytes
Presence
Presence
Presence
Presence
Presence
Reset
Reset
Reset
CCh
CCh
CCh
BEh
4Eh
48h
Reset
Reset
BEh
55h
44h
55h
Master issues reset pulse.
DS1822-PAR responds with presence pulse.
Master issues Skip ROM command.
Master issues Write Scratchpad command.
Master sends three data bytes to scratchpad (T
Master issues reset pulse.
DS1822-PAR responds with presence pulse.
Master issues Skip ROM command.
Master issues Read Scratchpad command.
Master reads entire scratchpad including CRC. The master then
recalculates the CRC of the first eight data bytes from the
scratchpad and compares the calculated CRC with the read CRC
(byte 9). If they match, the master continues; if not, the read
operation is repeated.
Master issues reset pulse.
DS1822-PAR responds with presence pulse.
Master issues Skip ROM command.
Master issues Copy Scratchpad command.
Master applies strong pullup to DQ for at least 10 ms while copy
operation is in progress.
Master issues reset pulse.
DS1822-PARs respond with presence pulse.
Master issues Match ROM command.
Master sends DS1822-PAR ROM code.
Master issues Convert T command.
Master applies strong pullup to DQ for the duration of the
conversion (t
Master issues reset pulse.
DS1822-PARs respond with presence pulse.
Master issues Match ROM command.
Master sends DS1822-PAR ROM code.
Master issues Read Scratchpad command.
Master reads entire scratchpad including CRC. The master
then recalculates the CRC of the first eight data bytes from the
scratchpad and compares the calculated CRC with the read
CRC (byte 9). If they match, the master continues; if not, the
read operation is repeated.
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conv
).
COMMENTS
COMMENTS
H
, T
H
, T
L
, and
L
, and config).
DS1822-PAR