DS1616 ,Temperature and Three Input MUXed 8-bit Data Recorderapplications requiring datalogging over short or long time frames.The RTC provides seconds, minutes ..
DS1616 ,Temperature and Three Input MUXed 8-bit Data RecorderPIN DESCRIPTION63 bins with +2.0C resolutionV - Battery SupplyBAT Records long-term ADC data hist ..
DS1616 ,Temperature and Three Input MUXed 8-bit Data RecorderFEATURES PIN ASSIGNMENT (Top View) Measures four channels of data:1 24V VBAT CC Integrated 8-bit ..
DS1620 ,Digital Thermometer and ThermostatPIN DESCRIPTIONDQ - 3-Wire Input/OutputCLK/ CONV - 3-Wire Clock Input andStand-alone Convert InputR ..
DS1620+ ,Digital Thermometer and ThermostatDS1620Digital Thermometer andThermostat
DS1620S ,Digital Thermometer and ThermostatPIN DESCRIPTIONDQ - 3-Wire Input/OutputCLK/ CONV - 3-Wire Clock Input andStand-alone Convert InputR ..
DTD122JK , 500mA / 50V Digital transistors (with built-in resistors)
DTD123EK , 500mA / 50V Digital transistors (with built-in resistors)
DTD123TK , 500mA / 40V Digital transistors (with built-in resistors)
DTD123YKT146 , DTD123YK
DTD123YS , Digital transistors (built-in resistors)
DTD133HK , Digital transistors (Includes resistors)
DS1616
Temperature and Three Input MUXed 8-bit Data Recorder
FEATURESMeasures four channels of data:Integrated 8-bit temperature sensorIntegrated 8-bit analog-to-digital
converter (ADC) with a three-input muxDigital thermometer measures temperature
-40�C to +85�C in +0.5�C increments with
�2�C accuracyReal-time clock/calendar (RTC) in BCD
format counts seconds, minutes, hours, date,
month, day of the week, and year with leap-year compensation; fully Y2K-compliantAutomatically wakes up and measures
temperature and/or ADC data at user-
programmable intervals from 1 to 255
minutes2048-byte datalog memoryRecords long-term temperature histogram in
63 bins with +2.0�C resolutionRecords long-term ADC data histogram in 64bins with 4-bit resolution/bin (32 mV/bin) for
ADC Channel 1Programmable temperature-high and -low
alarm trip pointsProgrammable ADC data-high and -low alarmtrip pointsRecords time stamp and duration when
temperature or ADC Channel 1 Data leaves
the interval specified by the trip pointsTwo serial interface options:-3-wire synchronous serial interfaceAsynchronous serial interface compatible
with standard UARTsMemory partitioned into 32-byte pages for
packetizing dataOn-chip 16-bit CRC generator to safeguard
data read operations in asynchronous
communications modeUnique, factory lasered 64-bit serial number
PIN ASSIGNMENT (Top View)
Package Dimension Informationhttp:///TechSupport/DallasPackInfo.htm
PIN DESCRIPTIONVBAT- Battery Supply- Crystal InputX2- Crystal Output
AINx- Analog in
INSPEC- In-Specification Output
OUTSPEC- Out-of-Specification Output
INT- Interrupt Output
GND- Digital Ground
AGND- Analog Ground- Start/Status Input
RST- 3-Wire Reset Input
I/O- 3-Wire Input/OutputSCLK- 3-Wire Clock Input- Transmit Output- Receive Input
COMSEL- Communication Select
VCC- +5V SupplyVBATVCC
INT
COMSEL
SCLK
I/O
RST
OUTSPEC
INSPEC
N.C.
N.C.
N.C.
GND
GND
GND
DS1616 24 DIP (600mil)DS1616S 24 SO (300mil)
DS1616
Temperature and Three-Input
DS1616
ORDERING INFORMATION
DESCRIPTIONThe DS1616 is an integrated temperature/data recorder. It combines a real-time clock (RTC),
temperature sensor, and a three input muxed 8-bit Analog-to-Digital Converter (ADC). Data logging issupported for all four data channels and the and histogram functionality is supported for the temperature
sensor and ADC Channel 1 only. A programmable sample rate feature makes the device ideal for
applications requiring datalogging over short or long time frames.
The RTC provides seconds, minutes, hours, day, date, month, and year information with leap yearcompensation, Year 2000 compliance, and also provides an alarm interrupt. Temperature measurement is
provided via integrated thermal technology which can measure temperatures from -40�C to +85�C in
0.5�C increments. An integrated three input muxed 8-bit ADC allows the device to record data from
other types of sensors.
The datalog function samples data at a user-defined sample rate and writes the data to the Datalog
memory. A total of 2048 bytes of data may be recorded. If only one data channel is selected, a total of
2048 samples can be recorded for that channel. If two channels are enabled, each channel can record
1024 samples. If three or four channels are enabled, each channel can record 512 samples. In the case ofonly three channels enabled, the location corresponding to the disabled channel will be 0 to allow the roll-
over function to work smoothly.
Histogram functionality is provided for the Thermal Sensor and ADC Channel 1, and is implemented by
sampling the data and then incrementing the count value in a data bin associated with that value. The
DS1616 provides 63 2-byte data bins in 2�C increments for the temperature channel and 64 2-byte data
bins in 4-bit resolution steps (32mV/bin) for the ADC Data Channel 1. The sampling rate can be
programmed at intervals ranging from once per minute to once every 255 minutes.
The DS1616 provides programmable high- and low-temperature alarm trip points that allow the device to
monitor whether the temperature stays within desired limits. Likewise, high- and low- trip points can be
programmed for the ADC data. The device can drive an interrupt or status pin if the ADC data falls
outside of the programmable limits. The Temperature Sensor and Channel 1 of the ADC can also have
any event that falls outside of the programmed limits recorded with a time and date stamp and theduration of the out-of-limits condition for additional analysis in the Alarm Memory. The DS1616 can be
programmed to begin sampling data via a pushbutton input or via a command sent over the serial
interface by a host machine.
A 64-bit serial number is available for unique product identification and tracking.
OVERVIEWThe block diagram in Figure 1 shows the relationship between the major control and memory sections of
the DS1616. The device has six major data components: 1) RTC and control blocks, 2) 32-byte User NV
RAM with 64-bit lasered serial number, 3) 96 bytes of alarm event/duration memory, 4) 128 bytes of
DS1616
DS1616 Block Diagram Figure 1
SIGNAL DESCRIPTIONSThe following paragraphs describe the function of each pin.
VCC - VCC is a +5-volt input supply. Communication with the DS1616 can take place only when VCC isconnected to a +5-volt supply.
Vbat - Battery input for standard lithium cell or other energy source. All functions of the DS1616 with theexception of the serial interface circuitry are powered by Vbat when VCC < Vbat. All functions are
powered by VCC when VCC > Vbat. If a battery or other energy source is not used, Vbat should be
connected directly to GND.
GND - GND connections are not internally connected, so all GND connections must be connected
directly to ground.
AGND - Analog ground should be connected directly to digital ground externally to eliminate ground
noise and potential differences.
COMSEL (Communication Select Input) - This pin determines whether serial communication isasynchronous or synchronous. When pulled high to VCC, communication is synchronous and will take
place via the SCLK, I/O, and RST pins. When COMSEL is tied to ground, asynchronous communication
OSCILLATOR
AND
DIVIDER
A/D
CONVERTER
CONTROL
LOGIC
DATALOG MEMORY
HISTOGRAM MEMORY
ALARM TIME STAMP
AND DURATION
LOGGING MEMORY
USER NVRAM
RTC AND CONTROL
REGISTERS
INTERNAL RTC
AND CONTROL
REGISTERS
SERIAL
INTERFACEMEMORY
FUNCTION
CONTROLTx
INSPEC
OUTSPEC
INT
COMSEL
I/O
RST
SCLK
OPTIONAL
SERIAL NUMBER
AINTEMPERATURE
SENSOR
DS1616
Tx (Transmit Output) - Transmit output of the asynchronous serial interface. Tx is tri-stated wheneverVCC < Vbat.
Rx (Receive Input) - Receive input of the asynchronous serial interface.
SCLK (3-Wire Serial Clock Input) - The SCLK pin is the serial clock input for the 3-wire synchronouscommunications channel.
I/O (3-Wire Input/Output) - The I/O pin is the data Input/Output signal for the 3-wire synchronouscommunications channel.
RST (3-Wire Reset Input) - The RST pin is the communications reset pin for the 3-wire synchronous
communications channel.
I
(Interrupt Output) - The INT pin is an open drain active low output that can be connected to an
interrupt input of a microprocessor. The INT output remains low as long as the status bit causing the
interrupt is present and the corresponding interrupt-enable bit is set.
INSPEC (Open Drain In-Specification Output) - This pin, in conjunction with the OUTSPEC pin, is
used to signal the status of the operation and data of the DS1616.
OUTSPEC (Open Drain Out-of-Specification Output) - This pin, in conjunction with the INSPEC pin,
is used to signal the status of the operation and data of the DS1616.
(Start/Status Button Input) - The ST pin provides two functions. First, when enabled as the datalog
start source (SE bit in Control 1 register is a logic 1), the ST pin is used to instruct the DS1616 to begin
recording data based on the programmed start delay and data sample rate. The ST pin must be held lowfor at least 0.5 seconds for a datalog mission to begin.
Secondly, the ST pin can be used to poll the status of the recorded data. After datalogging has begun, the pin instructs the DS1616 to report the status of the recorded data via the INSPEC and OUTSPEC pins.
AIN1, AIN2, AIN3 (Analog Inputs) - The AINx pins are the muxed inputs to the ADC.
X1, X2 - Connections for a standard 32.768 kHz quartz crystal, Daiwa part number DT-26S or
equivalent. For greatest accuracy, the DS1616 must be used with a crystal that has a specified load
capacitance of 6 pF. There is no need for external capacitors or resistors. Note: X1 and X2 are very high
impedance nodes. It is recommended that they and the crystal be guard-ringed with ground and that high
frequency signals be kept away from the crystal area. For more information on crystal selection and
crystal layout considerations, refer to Application Note 58: Crystal Considerations with Dallas Real-TimeClocks.
N.C. (No Connect) - These pins should be left unconnected or tied to ground.
DS1616
MEMORYThe memory map in Figure 2a shows the general organization of the DS1616. As can be seen in the
figure, the device is segmented into 32-byte pages. Pages 0 and 1 contain the RTC and Control registers
(see Figure 2b for more detail). The User NV RAM resides in page 2. Pages 17 to 19 are assigned to
storing the alarm time stamps and durations and pages 64 to 71 are reserved for histogram memory. The
data logging memory covers pages 128 to 191. Memory pages 3 to 16, 20 to 63, 68 to 127, and 192 andup are reserved for future extensions.
The end user can write only to the RTC and Control registers and the User NV RAM. The rest of the
memory map is read-only from the end user’s perspective.
DS1616 MEMORY MAP Figure 2aFirst 8 bytes**Last 8 bytes
DS1616
DS1616 RTC AND CONTROL PAGE Figure 2b
DS1616
DS1616 ALARM TIME STAMPS AND DURATIONS FOR THE THERMAL
SENSOR AND ADC CHANNEL 1 Figure 2c
DS1616 TEMPERATURE HISTOGRAM DATA BINS Figure 2d
DS1616 ADC DATA HISTOGRAM DATA BINS Figure 2e
THERMAL SENSORThe key to temperature monitoring in the DS1616 is an integrated thermal sensor. The thermal sensor
can measure temperature from -40�C to +85�C in 0.5�C increments (Fahrenheit equivalent is -40�F to
+183.2�F in 1.8�F increments). The thermal sensor provides an accuracy of �2�C.
DS1616
The thermal sensor is enabled by setting the CS0 bit of the Control 2 register to a logic 1. If the CS0 bit
is a logic 0, the thermal sensor will not be activated during a datalogging mission or for an individual
Read Data command. If CS0 = 0, the value in the Current Temperature register will be 11111111b.
The format of temperature data is defined such that the temperature value is maintained in a single byte of
data. Table 1 illustrates the format of the temperature data byte format. The values of T[7..0] range from
00000000b (for -40�C) to 11111010b (for +85�C). Each increment in the value of T[7..0] represents an
increase in temperature of 0.5�C. The following formula can be used to translate the temperature data
byte value into degrees Celsius: �C = 0.5(T[7..0]) - 40
TEMPERATURE DATA BYTE FORMAT Table 1MSbLSb
When a datalog mission has been initiated and the thermal sensor is enabled (CS0=1), the DS1616
provides temperature recording at regular intervals. However, the device also allows for immediate
temperature sensing upon a user’s command when the device is not currently on a datalog mission andthe thermal sensor is enabled (CS0=1). This is accomplished by issuing the Read Data command to the
DS1616 over the serial interface.
The most recently recorded temperature value is written to the Current Temperature register, regardless of
whether that value was recorded from a datalog mission or from the issuance of the Read Data command.The status of the contents of this register is provided by the Data Ready (DR) bit in the Status 1 register.
If DR is a logic 1, the data is valid. If DR is a logic 0, the data may not be reliable. If CS0 in the Control
2 register is a 0 such that the thermal sensor is disabled, the value in the Current Temperature register will
be 11111111b. The Read Data command will not output this byte of data.
During a datalog mission, the DR bit is cleared to a logic 0 when a temperature conversion has been
initiated and is set to a logic 1 upon the completion of the conversion. Likewise, the DR bit is cleared
immediately after the Read Data command is issued and is set to a logic 1 upon the completion of the
conversion. The Read Data command will only read the values in the current temperature/ADC data that
have been enabled by the CSx[03] bits in the control 2 register.
ANALOG-TO-DIGITAL CONVERTER (ADC)The DS1616 contains an integrated 8-bit ADC with a 3 to 1 input mux to allow multiple sensors to be
monitored. An on-chip voltage reference is also provided by an integrated band gap circuit (2.04V �3%).
The ADC input voltage must not be greater than the battery voltage.
An analog-to-digital conversion is the process of assigning a digital value to an analog input voltage.
This code represents the input value as a fraction of the full scale voltage (FSV) range. Thus the FSV
range is then divided by the ADC into 256 codes (8 bits). The FSV range is bounded by an upper limit
equal to the reference voltage and the lower limit, which is ground. The 2.04V (typical) bandgap
reference provides a resolution of 8mV between codes.
An input voltage equal to the reference voltage converts to FFh while an input voltage equal to ground
converts to 00h. The relative linearity of the ADC is �0.5 LSB.
DS1616
allows for immediate data conversion upon a user’s command when the device is not currently
performing a conversion and one or more of the Analog Inputs are enabled (CS[1-3] = 1). This is
accomplished by issuing the Read Data command to the DS1616 over the serial interface.
The most recently recorded data value is written to the Current Data register that corresponds to the
analog channel(s) that is(are) enabled, regardless of whether that value was recorded from a datalog
mission or from the issuance of the Read Data command. The status of the contents of this register is
provided by the Data Ready (DR) bit in the Status 1 register. If DR is a logic 1, the data is valid. If DR isa logic 0, the data may not be reliable. If a channel is not enabled, CS[1-3] is a logic 0, the contents of
the corresponding Current Data register will be 00000000b and not outputted when a Read Data
command is issued.
During a datalog mission, the DR bit is cleared to a logic 0 when a data conversion has been initiated and
is set to a logic 1 upon the completion of the conversion. Likewise, the DR bit is cleared immediatelyafter the Read Data command is issued and is set to a logic 1 upon the completion of the conversion.
DATA LOGGINGWhen the DS1616 datalogging function is enabled, the device is said to be on a “datalog mission” until
the datalogging is stopped.
During a datalog mission, temperature and/or ADC samples are successively written to the Datalog
memory pages. These memory pages are located at addresses 1000h to 17FFh.
The end user can program the DS1616 to record data from all four data channels or just one channel.
Channel selection is determined by the setting the Channel Select bits (CS0, CS1, CS2 and CS3) in theControl 2 register to the appropriate states. A 1 in the CSx bit will enable the channel and allow the
results to be reported, while a 0 will disable the channel, prevent its data from being recorded, prevent the
data from being reported by the Read Data command, and set the contents of the memory location for the
Current Data register corresponding to that channel to a constant value, all 1s for the thermal sensor or all
0s for the ADC channels.
When 3 or 4 data channels are selected, the first data sample is written to address location 1000h, the
second is written to address location 1001h. The address is incremented with each additional data
sample, with samples alternating between the enabled channels. The second sample is always measured
immediately after the completion of the first measurement with the third and forth samples following thesecond. The order of the sampling is the same as the order of the Channel Select registers. CS0 will be
sampled first, if it is enabled, followed by CS1, CS2 and CS3 if they are enabled. Any disabled channels
will be skipped. A total of 2048 registers have been reserved for datalog data, providing a total of 512
samples for each channel.
When three out of the four channels are enabled, a fourth byte of all 0s will be recorded in the Datalog
Memory after the three bytes of data from the enabled channels in order to allow the data to rollover and
remain in the correct positions.
When two data channels are selected, the first data sample is written to address location 1000h and thesecond is then written to address location 1001h. The address is incremented with each additional data
sample, with samples alternating between the enabled channels.
The second sample is always measured immediately after the completion of the first measurement. A
DS1616
If one data channel is selected, the entire datalog memory is dedicated to that one channel and therefore a
total of 2048 samples can be recorded.
A datalog mission can be initiated via two different methods: by a host instruction over the serialinterface or by a pushbutton input. When the SE bit in the Control 1 register is cleared to a logic 0, the
start function of the ST pin is disabled and writing any non-0 value to the Sample Rate register will start a
mission. When the SE bit is set to a logic 1, the pushbutton method of starting a mission is enabled.
Under this mode of operation, the DS1616 will begin a datalog mission when a non-0 value has been
written to the Sample Rate register and the ST pin has been held low for at least 0.5 seconds.
The sample rate during a datalog mission is equal to the value written to the Sample Rate register
multiplied by one minute. Writing a 0 to the MIP bit in the Status 1 register completes the mission.
Upon initiation of datalog mission by either method, the DS1616 will do two things:
1. The INSPEC and OUTSPEC pins will generate four low pulses simultaneously.
2. The Mission-in-Progress (MIP) bit in the Status 1 register is set to a 1.
The time at which the first datalog sample is measured is dependent upon the value in the Start Delay
registers. The two-byte Start Delay register provide a method for the end user to program a delay before
sampling commences. The delay is roughly equal to the value in the Start Delay register times one
minute. For example, if the Start Delay register contain a value of 10, then the device will begin
recording data approximately ten minutes after it received either the pushbutton start signal or startinstruction. The Start Delay register are located at addresses 0012h and 0013h, with register 0012h being
the LSB and register 0013h being the MSB. The Start Delay register decrements every time the Seconds
register rolls over from 59 to 00. When this Start Delay register contains a 00, the first datalog sample
will be taken when the seconds register rolls over from 59 to 00.
The user has two options for dealing with the potential occurrence of a data overrun (i.e., more than 2048
total data samples). The first option is to enable the rollover feature of the DS1616. This is accomplished
by setting the Rollover bit (bit 3 of the Control 1 register) to 1. When the Rollover feature is enabled,
new data is written over previous data, starting with address 1000h. For example, if the Datalog memory
has been completely filled (i.e., 2048 data samples have been recorded) the next data sample will bewritten to address location 1000h and the address pointer will be incremented with each successive data
sample.
The second option for dealing with data overrun is to stop recording data after the datalog memory has
been completely used. In other words, the DS1616 will stop recording data values after 2048 datasamples. This feature is enabled by disabling the Rollover feature. (Bit 3 of the Control 1 Register) set to
It should be noted that during a datalog mission, a time stamp for the first sample is recorded, but is not
included for each subsequent sample. However, the time of acquisition for any data sample is easilydetermined by considering the start time, the sample rate, the value in the Current Sample Counter, and
the address of the particular data sample in the datalog memory. If no rollover has occurred in the
datalog memory, the sample time associated with any particular data point can be calculated by
multiplying the address of the data by the sample rate and adding that to the stored start time value.
If the rollover feature has been enabled, the user can determine if rollover has occurred by reading the
DS1616
occurred. If rollover has occurred, the user needs to determine how many times rollover occurred in
determining the sample time for any particular data sample.
As a safety measure, the DS1616 has been designed such that the end user cannot write to the DatalogMemory. This prevents the falsification of datalog data by writing values to datalog registers.
DATA HISTOGRAMWhile on a datalog mission, the DS1616 also records a histogram of the temperature and/or ADC
Channel 1 data. The temperature histogram is provided by a series of 63 2-byte “data bins” that are
located in the Temperature Histogram memory pages (addresses 0800h to 087Fh). Each bin consists of a
16-bit binary counter that is incremented each time an acquired temperature value falls into the range ofthe bin. The least significant byte of each bin is stored at the lower address. Bin 0 begins at memory
address 0800h, bin 1 at 0802h, and so on up to 087Ch for bin 62. See Figure 2d for temperature
histogram address map.
Likewise, the ADC Channel 1Data histogram is provided by a series of 64 2-byte “data bins” that arelocated in the ADC Data Histogram memory pages (addresses 0880h to 08FFh). Each data bin represents
four ADC codes (32mV/bin). For example, bin 0 counts the frequency of ADC codes from 00-03h. Bin
1 counts the frequency of ADC codes from 04-07h, and so on. See Figure 2e for ADC Data histogram
address map.
After a temperature and/or ADC conversion is completed, the number of the bin to be updated is
determined by dropping the two least significant bits of the binary data value. For example, bin 0 of the
temperature histogram will be updated with every temperature reading from -40�C to -38.5�C. In the
same way, bin 1 is associated with the range of -38�C to -36.5�C. Bin 62, finally, counts temperature
values in the range of +84�C to +85.0�C. Since the device will not generate temperature values higher
than 85.0�C, bin 62 covers only three temperature values. The memory for a potential 64th bin exists, but
will always read 0s.
Since each data bin contains 2 bytes, a total of 65,535 samples can be accumulated. If more samples are
measured, the data bin will remain at the maximum value. In other words, the data bin value will not roll-
over in the event of an overrun.
ALARM LOGGINGFor some applications it may be essential to record exactly when a data sample exceeds a predefinedtolerance band and for how long the violation remained. The Thermal Sensor (CS1) and ADC Channel 1
(CS2) are equipped with the alarm logging feature. The ADC Channels 2 & 3 do not have the logging
feature, but they still have the alarm feature and the ability to trigger an interrupt. If an out of tolerance
condition occurs on channels 2 or 3, the time and duration can be calculated from the Memory if the
memory has not rolled over since the alarm.
A tolerance band is specified by means of the Temperature Alarm registers (addresses 000Bh and 000Ch)
and the ADC Data Alarm [1-3] registers (addresses 0024h to 0029h). See figure 2b for more details on
the memory mapping. One can set a high and a low threshold. As long as the data samples stay within
the tolerance bands (i.e., are higher than the low threshold and lower than the high threshold), the DS1616will not record any alarm.
If the temperature violates the temperature band, the DS1616 will generate an alarm and set either the
DS1616
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-High1 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 InterruptEnable (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. Oneaddress 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 particulartime 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 PINSTwo 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 userstarts 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.
DS1616
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 recordedtemperature 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 STpin low for at least half a second after the datalogger has already been started.
CLOCK, CALENDAR, AND ALARMThe 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 arelogic 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 areset to 1, an alarm will occur every second.
As a security measure to prevent unauthorized tampering, changing any value in the RTC and Control
DS1616
TIME OF DAY ALARM BITS Table 2
SPECIAL PURPOSE REGISTERSThe following description defines the operation of the special function registers of the DS1616.
CONTROL 1 REGISTERMSbLSb
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 DS1616 is placed into a low-power standby mode with a current drain of less than 100 nanoamps at
room temperature. When Vcc is applied or when MIP =1, the oscillator is active regardless of the state ofthis bit.
CLR - Clear Enable - This bit enables the Clear Memory command. When this bit is set to a 1 and theClear Memory command is subsequently issued, the datalog, histogram, Temperature Alarm, Current
Samples, Start Time Stamp, Start Delay, Sample Rate register, and ADC Data Alarm are all cleared to 0.Following the issuing of the Clear Memory command, the CLR bit is also cleared to 0. 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 0 and the contents of the datalog, histogram, temperature alarms, Current Samples registers,
Start Delay, Sample Rate, and ADC Data alarm register are unchanged.
SE - Start Enable - This bit enables the “start” function of the ST input. When SE is a logic 1, the STinput is enabled as the start pin for datalogging operation. When enabled, datalogging operation begins
when the Sample Rate register contains a non-0 value AND theST pin has been held low for at least
0.5 seconds. When SE is a logic 0, writing any non-0 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 tothe Start Delay register has elapsed.
RO - Roll-Over - This bit determines whether the datalog function of the DS1616 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 datalog memory will “roll over” after all 2048 registers in the datalog memory have been used.In other words, after the 2048th register is written, the following sample will be written to register 0000,
