DS1922E-F5 MAXIM [Maxim Integrated Products], DS1922E-F5 Datasheet - Page 16

• Manufacturer Part Number: DS1922E-F5
• Description: High-Temperature Logger iButton with 8KB Data-Log Memory
• Manufacturer: MAXIM [Maxim Integrated Products]

The fastest way to determine whether a programmed
temperature threshold was exceeded during a mission
is through reading the Alarm Status register. In a net-
worked environment that contains multiple DS1922E
iButtons, the devices that encountered an alarm can
quickly be identified by means of the Conditional
Search command (see the 1-Wire ROM Function
Commands section). The temperature alarm only
occurs if enabled (see the Temperature Sensor Alarm
section). The BOR alarm is always enabled.
Bit 7: Battery-On Reset Alarm (BOR). If this bit reads
1, the device has performed a power-on reset. This
indicates that the device has experienced a shock big
enough to interrupt the internal battery power supply.
The device may still appear functional, but it has lost its
factory calibration. Any data found in the data-log
memory should be disregarded.
Bit 1: Temperature High Alarm Flag (THF). If this bit
reads 1, there was at least one temperature conversion
during a mission revealing a temperature equal to or
higher than the value in the Temperature High Alarm
register. A forced conversion can affect the THF bit.
This bit can also be set with the initial alarm in the
SUTA = 1 mode.
Bit 0: Temperature Low Alarm Flag (TLF). If this bit
reads 1, there was at least one temperature conversion
during a mission revealing a temperature equal to or
lower than the value in the Temperature Low Alarm reg-
ister. A forced conversion can affect the TLF bit. This
bit can also be set with the initial alarm in the SUTA = 1
mode.
High-Temperature Logger iButton with 8KB
Data-Log Memory
Note: There is only read access to this register. Bits 4 to 6 have no function. They always read 1. Bits 2 and 3 have no function with
the DS1922E. They always read 0. The alarm status bits are cleared simultaneously when the Clear Memory Function is invoked. See
memory and control functions for details.
Note: There is only read access to this register. Bits 0, 2, 5, 6, and 7 have no function.
16
ADDRESS
ADDRESS
0214h
0215h
______________________________________________________________________________________
BIT 7
BIT 7
BOR
1
BIT 6
BIT 6
1
1
Alarm Status
BIT 5
BIT 5
1
0
WFTA
BIT 4
BIT 4
1
The information in the General Status register tells the
host computer whether a mission-related command
was executed successfully. Individual status bits indi-
cate whether the DS1922E is performing a mission,
waiting for a temperature alarm to trigger the logging of
data or whether the data from the latest mission has
been cleared.
Bit 4: Waiting for Temperature Alarm (WFTA). If this
bit reads 1, the Mission Start Upon Temperature Alarm
was selected and the Start Mission command was suc-
cessfully executed, but the device has not yet experi-
enced the temperature alarm. This bit is cleared after a
temperature alarm event, but is not affected by the
Clear Memory command. Once set, WFTA remains set
if a mission is stopped before a temperature alarm
occurs. To clear WFTA manually before starting a new
mission, set the high temperature alarm (address
0209h) to +15°C and perform a forced conversion.
Bit 3: Memory Cleared (MEMCLR). If this bit reads 1,
the Mission Timestamp, mission samples counter, and
all the alarm flags of the Alarm Status register have
been cleared in preparation of a new mission.
Executing the Clear Memory command clears these
memory sections. The MEMCLR bit returns to 0 as soon
as a new mission is started by using the Start Mission
command. The memory must be cleared for a mission
to start.
Bit 1: Mission in Progress (MIP). If this bit reads 1,
the device has been set up for a mission and this mis-
sion is still in progress. The MIP bit returns from logic 1
to logic 0 when a mission is ended. See the Start
Mission and Stop Mission function commands.
MEMCLR
BIT 3
BIT 3
0
BIT 2
BIT 2
0
0
General Status Register
Alarm Status Register
BIT 1
BIT 1
THF
MIP
General Status
BIT 0
BIT 0
TLF
0