Rainbow Electronics DS7505 - Manual (Page 8)

DS7505
Configuration Register
The configuration register allows the user to program
various DS7505 options such as conversion resolution,
thermostat fault tolerance, thermostat polarity, thermo-
stat operating mode, and shutdown mode. The configu-
ration register is arranged as shown in Figure 5 and
detailed descriptions of each bit are provided in Table
2. The user has read/write access to all bits in the con-
figuration register except the MSB (NVB bit), which is a
read-only bit. All bits in the register but the NVB bit are
NV EEPROM backed by shadow SRAM, and thus
power-up in their programmed state. Once written to
the shadow SRAM, values can be stored in EEPROM
by issuance of a Copy Data command from the master
(see the
Command Set section for more details). If the
values are not copied to the EEPROM, the device pow-
ers up with the factory default settings or the last values
that were copied to the EEPROM. The NVB bit is SRAM
and powers up in the state shown in Table 2.
Digital Thermometer and Thermostat
8 _______________________________________________________________________________________
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB
NVB R1 R0 F1 F0 POL TM SD
Figure 5. Configuration Register
Table 2. Configuration Register Bit Descriptions
BIT NAME FUNCTIONAL DESCRIPTION
NVB
NV Memory Status
Power-up state = 0, read only
NVB = 1—Write to an NV memory cell is in progress.
NVB = 0—NV memory is not busy.
R1
Conversion Resolution Bit 1 Factory power-up state = 0
Sets conversion resolution (see Table 3).
R0
Conversion Resolution Bit 0 Factory power-up state = 0
Sets conversion resolution (see Table 3).
F1
Thermostat Fault Tolerance Bit 1 Factory power-up state = 0
Sets the thermostat fault tolerance (see Table 4).
F0
Thermostat Fault Tolerance Bit 0 Factory power-up state = 0
Sets the thermostat fault tolerance (see Table 4).
POL
Thermostat Output (O.S.) Polarity
Factory power-up state = 0
POL = 0—O.S. is active low.
POL = 1—O.S. is active high.
TM
Thermostat Operating Mode
Factory 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
Factory 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.