Table 2. configuration register bit descriptions, Table 3. resolution configuration, Table 4. fault tolerance configuration – Rainbow Electronics DS75LX User Manual
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DS75LX: Digital Thermometer and Thermostat with Extended Addressing
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Table 2. Configuration Register Bit Descriptions
BIT NAME
DESCRIPTION
0
Reserved
Power-Up State = 0
The master can write to this bit, but it always reads out as a 0.
R1
Conversion Resolution Bit 1
Power-Up State = 0
Sets conversion resolution (see Table 3).
R0
Conversion Resolution Bit 0
Power-Up State = 0
Sets conversion resolution (see Table 3).
F1
Thermostat Fault Tolerance Bit 1
Power-Up State = 0
Sets the thermostat fault tolerance (see Table 4).
F0
Thermostat Fault Tolerance Bit 0
Power-Up State = 0
Sets the thermostat fault tolerance (see Table 4).
POL
Thermostat Output (O.S.) Polarity
Power-Up State = 0
POL = 0 — O.S. is active low.
POL = 1 — O.S. is active high.
TM
Thermostat Operating Mode
Power-Up State = 0
TM = 0 — Comparator mode.
TM = 1 — Interrupt mode.
See the Operation—Thermostat section for a detailed description of
these modes.
SD
Shutdown
Power-Up State = 0
SD = 0 — Active conversion and thermostat operation.
SD = 1 — Shutdown mode.
See the Shutdown Mode section for a detailed description of this mode.
Table 3. Resolution Configuration
R1 R0
THERMOMETER
RESOLUTION (BITS)
MAX CONVERSION
TIME (ms)
0 0
9
25
0 1
10
50
1 0
11
100
1 1
12
200
Table 4. Fault Tolerance Configuration
F1 F0
CONSECUTIVE OUT-OF-LIMITS
CONVERSIONS TO TRIGGER O.S.
0 0
1
0 1
2
1 0
4
1 1
6
REGISTER POINTER
The four DS75LX registers each have a unique two-bit pointer designation, which is defined in Table 5. When
reading from or writing to the DS75LX, the user must “point” the DS75LX to the register that is to be accessed.
When reading from the DS75LX, once the pointer is set it remains pointed at the same register until it is changed.
For example, if the user wants to perform consecutive reads from the temperature register, the pointer only has to
be set to the temperature register one time, after which all reads will automatically be from the temperature register
until the pointer value is changed. On the other hand, when writing to the DS75LX, the pointer value must be
refreshed each time a write is performed, even if the same register is being written to twice in a row.
At power-up, the default pointer value is the temperature register so the temperature register can be read
immediately without resetting the pointer.
Changes to the pointer setting are accomplished as described in the 2-Wire Serial Data Bus.