ADT7482
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11
Status Registers
The status registers are read-only registers at
Addresses 0x02 (Status Register 1) and Address 0x23
(Status Register 2). They contain status information for the
ADT7482.
Table 12. STATUS REGISTER 1 BIT ASSIGNMENTS
Bit Mnemonic Function ALERT
7 BUSY 1 when ADC Converting No
6
LHIGH
(Note 1)
1 when Local High
Temperature Limit Tripped
Yes
5
LLOW
(Note 1)
1 when Local Low
Temperature Limit Tripped
Yes
4
R1HIGH
(Note 1)
1 when Remote 1 High
Temperature Limit Tripped
Yes
3
R1LOW
(Note 1)
1 when Remote 1 Low
Temperature Limit Tripped
Yes
2
D1 OPEN
(Note 1)
1 when Remote 1 Sensor
Open Circuit
Yes
1 R1THRM1 1 when Remote 1 THERM
Limit Tripped
No
0 LTHRM1 1 when Local THERM Limit
Tripped
No
1. These flags stay high until the status register is read, or they are
reset by POR.
Table 13. STATUS REGISTER 2 BIT ASSIGNMENTS
Bit Mnemonic Function ALERT
7 Res Reserved for Future Use No
6 Res Reserved for Future Use No
5 Res Reserved for Future Use No
4
R2HIGH
(Note 1)
1 when Remote 2 High
Temperature Limit Tripped
Yes
3
R2LOW
(Note 1)
1 when Remote 2 Low
Temperature Limit Tripped
Yes
2
D2 OPEN
(Note 1)
1 when Remote 2 Sensor
Open Circuit
Yes
1 R2THRM1 1 when Remote 2 THERM
Limit Tripped
No
0 ALERT 1 when ALERT Condition
Exists
No
1. These flags stay high until the status register is read, or they are
reset by POR.
The eight flags that can generate an ALERT are NOR’d
together. When any flags are high, the ALERT
interrupt
latch is set and the ALERT
output goes low (provided they
are not masked out).
Reading the Status 1 register clears the 5 flags, (Bit 6
through Bit 2) in Status Register 1, provided the error
conditions that caused the flags to be set have gone away.
Reading the Status 2 Register clears the three flags, (Bit 4
through Bit 2) in Status Register 2, provided the error
conditions that caused the flags to be set have gone away. A
flag bit can only be reset if the corresponding value register
contains an in-limit measurement or if the sensor is good.
The ALERT
interrupt latch is not reset by reading the
status register. It is reset when the ALERT
output has been
serviced by the master reading the device address, provided
the error condition has gone away and the status register flag
bits have been reset.
When Flag 1 and/or Flag 0 of Status Register 1 or Flag 1
of Status Register 2 are set, the THERM
output goes low to
indicate that the temperature measurements are outside the
programmed limits. The THERM
output does not need to be
reset, unlike the ALERT
output. Once the measurements are
within the limits, the corresponding status register bits are
reset automatically, and the THERM
output goes high. To
add hysteresis, program Register 0x21. The THERM
output
is reset only when the temperature falls below the THERM
limit minus hysteresis.
When Pin 8 is configured as THERM2
, only the high
temperature limits are relevant. If Flag 6 or Flag 4 of Status
Register 1 or Flag 4 of Status Register 2 are set, the
THERM2
output goes low to indicate that the temperature
measurements are outside the programmed limits. Flag 5
and Flag 3 of Status Register 1 and Flag 3 of Status
Register 2 have no effect on THERM2
. The behavior of
THERM2
is otherwise the same as THERM.
Bit 0 of the Status Register 2 is set whenever the
ADT7482 ALERT
output is asserted low. Read Status
Register 2 to determine if the ADT7482 is responsible for
the ALERT
. This bit is reset when the ALERT output is reset.
If the ALERT
output is masked, then this bit is not set.
Offset Register
Offset errors can be introduced into the remote
temperature measurement by clock noise or by the thermal
diode being located away from the hot spot. To achieve the
specified accuracy on this channel, these offsets must be
removed.
The offset values are stored as 10-bit, twos complement
values.
The Remote 1 Offset MSBs are stored in Register 0x11
and the LSBs are stored in Register 0x12 (low byte, left
justified). The Remote 2 Offset MSBs are stored in
Register 0x34 and the LSBs are stored in Register 0x35
(low byte, left justified).
The Remote 2 Offset can be written to or read from the
Remote 1 Offset Registers if Bit 3 of the
Configuration 1 register is set to 1. This bit should be
set to 0 (default) to read the Remote 1 offset values.
Only the upper 2 bits of the LSB registers are used. The
MSB of MSB offset registers is the sign bit. The minimum
offset that can be programmed is −128C, and the maximum
is +127.75C. The value in the offset register is added or
subtracted to the measured value of the remote temperature.
The offset register powers up with a default value of 0C
and has no effect unless a different value is written to it.
