DS1615 Datasheet, PDF (12/24 Pages) Dallas Semiconductor – Temperature Recorder

DS1615
TIME OF DAY ALARM BITS Table 2
ALARM REGISTER MASK BITS (BIT 7)
SECONDS MINUTES HOURS DAYS
1
1
1
1 Alarm once per second
0
1
1
1 Alarm when seconds match
0
0
1
1 Alarm when minutes and seconds match
0
0
0
1 Alarm when hours, minutes, and seconds match
0
0
0
0 Alarm when day, hours, minutes, and seconds match
SPECIAL PURPOSE REGISTERS
The following description defines the operation of the special function registers of the DS1615.
CONTROL REGISTER
MSb
EOSC
CLR
0
LSb
SE
RO
TLIE
THIE
AIE
EOSC - Enable oscillator - This bit controls the state of the oscillator in battery back-up mode only.
When set to logic 0, the oscillator is active. When this bit is set to a logic 1, the oscillator is stopped and
the DS1615 is placed into a low-power standby mode with a current drain of less than 100 nanoamps at
room temperature. When V_CC is applied or when MIP =1, the oscillator is active regardless of the state of
this bit.
CLR - Clear Enable This bit enables the Clear Memory command. When this bit is set to a one and the
Clear Memory command is subsequently issued, the datalog, histogram, Temperature Alarm, Current
Samples, Start Time Stamp, Start Delay, and Sample Rate register are all cleared to zero. Following the
issuing of the Clear Memory command, the CLR bit is also cleared to zero. If the Clear Enable bit is set,
but a command other than the Clear Memory command is issued next, the CLR bit is cleared to a zero
and the contents of the datalog, histogram, temperature alarms, Current Samples registers, Start Delay,
and Sample Rate register are unchanged.
ST - Start Enable - This bit enables the start function of the ST input. When SE is a logic 1, the ST input
is enabled as the start pin for datalogging operation. When enabled, datalogging operation begins when
the Sample Rate register contains a non-zero value AND then the ST pin has been held low for at least
0.5 seconds. When SE is a logic 0, writing any non-zero value to the Sample Rate register will start
datalogging operation.
Once datalog operation has been initiated, the first data sample occurs after the specified delay written to
the Start Delay register has elapsed.
RO - Roll-Over - This bit determines whether the data-log function of the DS1615 rolls over or stops
writing data to the datalog memory in the event that the datalog memory is completely filled. If RO is set
to a 1, the data-log memory will roll over after all 2048 registers in the datalog memory have been used.
In other words, after the 2048^th data sample, the following sample will be written to register 0000h,
overwriting the original data. Likewise, subsequent samples will increment through the datalog registers,
overwriting their data. If RO is cleared to a 0, no further data samples will be written to the datalog
memory after all datalog memory registers have been filled. Samples, however, will continue to be taken
and the appropriate histogram registers will be incremented with each sample. Likewise, the temperature
alarms will also continue to function.
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