Rainbow Electronics DS1616 - Manual (Page 13)

DS1616
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The INSPEC and OUTSPEC pins are used to provide visual feedback to the end user in the following
situations:
1. Datalog Mission Start
When a datalog mission is first initiated, the INSPEC and OUTSPEC pins will generate four low pulses
simultaneously to give the end user a visual indication that a datalog mission has begun.
2. Request for Status of Data
Following a user request for the status of recorded data, the INSPEC pin will generate four low pulses if
the recorded data is within the user-defined limits (as set in the Threshold registers). If the recorded
temperature data contains any readings that fall outside of these high- and low-temperature thresholds or
if the recorded ADC data from any of the three ADC channels that are enabled contains any readings that
fall outside of these high- and low-ADC Channel [1-3] Data thresholds, the
OUTSPEC pin will be pulsed
four times. If the request comes after the mission has started (i.e., MIP = 1), but before the first sample
has been recorded, the
INSPEC and OUTSPEC pins will generate a total of four low pulses alternately,
starting with the OUTSPEC pin.
The DS1616 provides two methods for the user to request the status of the data. The first method is to
send the Specification Test command over the serial interface. The second method is by holding the
ST
pin low for at least half a second after the datalogger has already been started.
CLOCK, CALENDAR, AND ALARM
The time and calendar information is accessed by reading/writing the appropriate register bytes. Note
that some bits are set to 0. These bits will always read 0 regardless of how they are written. The contents
of the time, calendar, and alarm registers are in the Binary-Coded Decimal (BCD) format and Year 2000
compliant.
The RTC can be read at any time and the values used in other parts of the system outside the data logger
by issuing a Read Page command for memory page 0. See figure 2C for more details on the RTC
memory map.
The DS1616 can run in either 12-hour or 24-hour mode. Bit 6 of the hours register is defined as the 12-
or 24-hour mode select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the
AM/PM bit with logic 1 being PM. In the 24-hour mode, bit 5 is the second 10-hour bit (20-23 hours).
The DS1616 also contains a time of day alarm. The alarm registers are located in registers 0007h to
000Ah. Bit 7 of each of the alarm registers are mask bits (see Table 2). When all of the mask bits are
logic 0, an alarm will occur once per week when the values stored in timekeeping registers 0000h to
0003h match the values stored in the time of day alarm registers. An alarm will be generated every day
when mask bit of the day alarm register is set to 1. An alarm will be generated every hour when the day
and hour alarm mask bits are set to 1. Similarly, an alarm will be generated every minute when the day,
hour, and minute alarm mask bits are set to 1. When day, hour, minute, and seconds alarm mask bits are
set to 1, an alarm will occur every second.
As a security measure to prevent unauthorized tampering, changing any value in the RTC and Control
registers (with the exception of the Status registers) will stop a datalog mission and clear the Mission-in-
Progress (MIP) bit.