Rainbow Electronics DS1720 - Manual (Page 6)

DS1720
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falling edge of the clock, and remain valid through the
rising edge.
When reading data from the DS1720, the DQ pin goes
to a high impedance state while the clock is high. Taking
RST low will terminate any communication and cause
the DQ pin to go to a high impedance state.
Data over the 3–wire interface is communicated LSB
first. The command set for the 3–wire interface as
shown in Table 3 is as follows; only these protocols
should be written to the DS1720, as writing other proto-
cols to the device may result in permanent damage to
the part.
Read Temperature [AAh]
This command reads the contents of the register which
contains the last temperature conversion result. The
next nine clock cycles will output the contents of this reg-
ister.
Write TH [01h]
This command writes to the TH (HIGH TEMPERA-
TURE) register. After issuing this command, the next
nine clock cycles clock in the 9–bit temperature limit
which will set the threshold for operation of the T
HIGH
output.
Write TL [02h]
This command writes to the TL (LOW TEMPERA-
TURE) register. After issuing this command, the next
nine clock cycles clock in the 9–bit temperature limit
which will set the threshold for operation of the T
LOW
output.
Read TH [A1h]
This command reads the value of the TH (HIGH TEM-
PERATURE) register. After issuing this command, the
next nine clock cycles clock out the 9–bit temperature
limit which sets the threshold for operation of the T
HIGH
output.
Read TL [A2h]
This command reads the value of the TL (LOW TEM-
PERATURE) register. After issuing this command, the
next nine clock cycles clock out the 9–bit temperature
limit which sets the threshold for operation of the T
LOW
output.
Read Counter [A0h]
This command reads the value of the counter byte. The
next nine clock cycles will output the contents of this
register.
Read Slope [A9h]
This command reads the value of the slope counter byte
from the DS1720. The next nine clock cycles will output
the contents of this register.
Start Convert T [EEh]
This command begins a temperature conversion. No
further data is required. In one–shot mode, the tempera-
ture conversion will be performed and then the DS1720
will remain idle. In continuous mode, this command will
initiate continuous conversions.
Stop Convert T [22h]
This command stops temperature conversion. No fur-
ther data is required. This command may be used to halt
a DS1720 in continuous conversion mode. After issuing
this command, the current temperature measurement
will be completed, and then the DS1720 will remain idle
until a Start Convert T is issued to resume continuous
operation.
Write Config [0Ch]
This command writes to the configuration register. After
issuing this command, the next eight clock cycles clock
in the value of the configuration register.
Read Config [ACh]
This command reads the value in the configuration reg-
ister. After issuing this command, the next eight clock
cycles output the value of the configuration register.