Unihedron SQM-LU-DL, Operator'S Manual

Page: 22 / 101

5 Hardware connections
Figure 5.4: Diagnostic LED timing diagram
Description of LED flashes:
A On for three seconds during the power-up/boot-load sequence. During this time, the unit is supplying power to the
sensor components and will also accept firmware updates.
B Log a reading if it is scheduled and is above the set threshold. The meter requires about 8 seconds to gather a valid
reading, Some readings may take much longer (300s max) to acquire.
C Shutdown: One quick flash for normal battery voltage (above 4.9V), more quick flashes if the battery voltage is too
low (2:4.8V, 3:4.6V, 4:4.4V, 5:4.2V, 6:4.0V). Battery voltage detection is performed at the end of the light meter
reading time (B) because low batteries drop during power drain and this is the voltage that the light meter reading
was recorded at.
D Wake from sleep at the minute mark to check if a recording should be logged. The LED comes on bright then fades
off within one second. Firmware before feature 49 had this step leave the LED on for three seconds solid.
E Same as step C.
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Unihedron SQM-LU-DL Operator’s Manual -
20220119