Histogram Description
10
DLR-TL001
Remaining Shelf Life calculation
Shelf Life is the length of time that perishable items are given before they
are considered unsuitable for sale or consumption. For many products the
spoilage rate increase of a perishable good is an exponential function of
temperature.
As well as the MKT, the remaining Shelf Life calculation is useful in order to
mo
nitor the status of an item during the shipment. The DLR-TL001 calcu-
lates the remaining Shelf Life by using a linear approximation of the Arrhe-
nius algorithm at each new sampling time. Shelf Life time can be en-/dis-
abled
toggling the state of the ARRE flag in the Control Register (RW) on
page 14.
The remaining Shelf Life (in hours) is calculated with the following formula:
where SHLref is the Shelf Life reference expressed in hours, Tn is the tem-
perature of the different samples expressed in °C, Tref is the reference tem-
perature expressed in °C, Q10 (unit less number) is defined as the ratio of
the
reaction rate constants at temperatures differing by 10 °C from the ref-
erence temperature and tn is the sampling interval expressed in minute for
the
selected bin.
The user can set a threshold value for the remaining Shelf Life; if the
remaining Shelf Life is lower than the threshold, the tag generates an alarm
setting to 1 the SHL_ALARM bit in the STATUS register. The remaining Shelf
Life value can be obtained reading the SHL_TIME register while the threshold
can be set writing the desired value in the SHL_THRESHOLD register.
The remaining Shelf Life value can be obtained reading the SHL_TIME regis-
ter while the threshold can be set writing the desired value in the SHL_-
THRESHOLD register.
Battery measurement and behavior
The DLR-TL001 tag includes a battery measurement circuitry that allows to
control the battery charge level.
Four battery charge levels are defined: Full (3), Normal (2), Low (1),
Empty
(0); values can be obtained reading the BAT_LSBIT and the BAT_MSBIT in the
STATUS register. The DLR-TL001 tag behave normally when the battery is at
the Full or Normal battery level, while it is automatically put in Sleep state
when the level reach the Low value.
When the battery level status is Low (1) or Empty (0) the battery level is con-
sidered critical so the condition is r
eported by the manual interface as
described in the relevant paragraph.
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