Rainbow Electronics DS1616 - Manual (Page 12)

DS1616
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duration of the alarming condition. The INT pin will be asserted by a high temperature alarm if the
Temperature-High Interrupt Enable (THIE) is set and will be asserted by a low temperature alarm if the
Temperature-Low Interrupt Enable (TLIE) is set.
Likewise, if ADC Channel 1 Data measurement violates the ADC Data band, either the ADC Data-High
1 or Data-Low 1 Flag (AHF1 or ALF1) will be set, a time stamp will be generated, and the duration of the
violation will be recorded. The
INT pin will be asserted by a high-alarm if the ADC Data-High Interrupt
Enable (AHIE) is set and will be asserted by a low-alarm if the ADC Data-Low Interrupt Enable (ALIE)
is set.
The device stores a time stamp of a violating condition by copying contents of the 3-byte Current
Samples Counter when the alarm occurred. The least significant byte is stored at the lower address. One
address higher than a time stamp, the DS1616 maintains a 1-byte duration counter that stores the number
of times the data was found to be beyond the threshold. If this counter has reached its limit after 255
consecutive data readings and the data has not yet returned to a level within the tolerance band, the device
will issue another time stamp at the next higher address and open another counter to record the duration.
If the data returns to normal before the counter has reached its limit, the duration counter of the particular
time stamp will not increment any further. Should the data again cross this threshold, new time stamp will
be recorded and its associated counter will increment with each data reading outside the tolerance band.
This algorithm is implemented for the low- as well as for the high- thresholds.
Time stamps and durations for low-temperature violations are stored in the Registers 0220h to 0237h
(24 bytes) and registers 0238h to 024Fh (24 bytes) are reserved for high-temperature violations.
Registers 0250h to 0267h are reserved for low-ADC Channel 1 Data violations and registers 0268h to
027Fh are reserved for high-ADC Channel 1 Data violations.
This allocation allows the recording of 24 individual alarm events and periods (six each for high-
temperature, low-temperature, high-ADC Channel 1 Data, and low-ADC Channel 1 Data violations).
The date and time of each of these periods can be determined from the Start Time Stamp and the time
sample rate. Figure 2c illustrates the Alarm Time Stamps and Durations registers.
INSPEC AND OUTSPEC PINS
Two special output pins, INSPEC and OUTSPEC , are intended to output the status of the DS1616. More
specifically, these pins can be used to control the illumination of LEDs. For example, the INSPEC pin can
be used to pulse a green LED and the OUTSPEC pin can be used to pulse a red LED. When the end user
starts a datalog mission or polls the device for information, one or both of these pins will be pulsed four
times. Depending on the status of the device, both pins will be pulsed simultaneously or just one pin will
be pulsed at a time. Each pulse is 62.5 ms in duration and will start every half second. See Figures 9 and
10 for further details.