DS1616 View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS1616

Temperature and Three Input MUX’ed 8-bit Data Recorder

Dallas Semiconductor -> Maxim Integrated 

DS1616

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 start

instruction. 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 be

written 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 simply stop recording data after the datalog memory

has been completely used. In other words, the DS1616 will stop recording data values after 2048 data

samples. This feature is enabled by disabling the Rollover feature. (Bit 3 of the Control 1 Register) set to

0.

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 easily

determined 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 value in

the Current Samples register. This register counts the total number of samples that have been acquired.

If this value is greater than 07FFh (decimal 2047) then the user knows that rollover has 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 Datalog

Memory. This prevents the falsification of datalog data by writing values to datalog registers.

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