A927ZET Technical Information Manual
35
Registers use example
The following procedure could be repeated for the internal and external temperature sensor.
Suppose that the user wants to monitor the temperature trend for frozen food as follows:
Low
Threshold
(°C)
High
Threshold
(°C)
Sampling
operating
mode
Limit
monitoring
Store
Samples
Store
Time-stamp
Sampling
Interval
(min.)
-20
-15
Continuous
Mode
enabled
Yes
Yes
15
With this configuration the tag is continuously logging the measured data with an interval of 15 minutes. The tag stores
the sensor data and the corresponding time-stamp. Violation of defined limits will raise an alert.
First of all, let’s set the low and high threshold value of temperature. The data need to be converted in hex format:
°C
HEX
Low Threshold
-20
FF38h
High Threshold
-15
FF6Ah
Then, set the Low/High Threshold registers:
Temperature Low Threshold:
set FF38h value in the USER memory, Bank 11b, Word address 16h (internal
sensor) and Word address 1026h (external sensor)
Temperature High Threshold:
set FF6Ah value in the USER memory, Bank 11b, Word address 17h (internal
sensor) and Word address 1027h (external sensor)
The sampling interval time, expressed in minutes, must be converted in seconds for the correct setting of the Sample
Time register in User Memory, Bank 11b, Word address 15h (internal sensor) and Word address 1025h (external
sensor):
min
sec
HEX
Sample Time
15
900
0384h
Set the temperature start time register in the User memory, bank 11b, word address 12h (internal sensor) and Word
address 1022h (external sensor). Suppose the date 15 Jun 2010 07:00, data need to be converted in Unix time-stamp
format:
Human time
dec
hex
Tue, 15 Jun 2010 07:00:00 GMT
1276585200
4C1724F0 h
Now configure the
Control Register:
Turn on the limit monitoring by setting LHM (
Limit High Monitoring)
and LLM (
Limit Low Monitoring)
bits=1 in the
Temperature Control Register in the USER memory, Bank 11b, Word address 11h (internal sensor) and Word address
1021h (external sensor).
In this way LLV (
Limit Low Violation Flag
) and LHV (
Limit High Violation Flag
) in the
Status register
bits go to 1 when
the value of temperature measured by the sensor is below/above the defined values for the Low/High Threshold.
In this example we consider a
continuous
sampling operation mode, so set the bit L=1 and bit M=0 in the Temperature
Control Register in the USER memory, Bank 11b, Word address 11h (internal sensor) and Word address 1021h
(external sensor).
Then define the
storing operating mode
(Time-stamped data in this example) setting Control register bit D= 1, bit TL=1:
Set SD bit=1 (SD has to be set after saving the Start Time).
Set reset bit RST=1(this bit has to be set when starting the new log).
The control register is now set as follows:
15…11
10
9
8
7
6
5
4
3
2
1
0
RFU
MM=0
SD=1
RST=1
L=1
D=1
TL=1
M=0
LHM=1
LLM=1
RFU
In this example, the sensor is logging with a sampling interval of 15 minutes. It is possible to verify temperature limits
violation simply by reading LLV and LHV bits in the Status register, without the need of reading the whole logged
memory.
