User guide

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SenseCam v2.3 User Guide Page 19 of 31 10/03/2009
this), then resume charging if required (and this time the red/green „charging‟ LED will be
operational.
If the SenseCam is run until it powers itself off, and then left for several weeks without re-
charging, the real-time clock may be reset to 0:00:00 on 1/1/2000. All images taken
subsequently will have the correct relative timing (assuming a further reset to the real-time
clock has not occurred). The real-time clock can be set to the correct time automatically
using the MSRC SenseCam Image Importer or manually using the BOOT.BAT or
TIME.CSV files (see Section 5).
With the default SenseCam configuration (fast charge enabled, see Section 4.8 below), the
battery will take around 3 hours to recharge from being completely flat. The SenseCam will
charge at the same rate whether connected to a USB mains adapter or a USB host or hub.
4.8. Adjusting the charge current
The maximum amount of current drawn by the SenseCam when charging can be set to one
of two different values to result in a fast or slow charge time (around 3 hours or 10 hours
respectively). The default operation is fast charge, which draws a current close to 500mA,
the maximum permitted over USB. However, due to the hardware USB device
implementation (see Section 6.1), when the SenseCam is enumerated over USB following
its connection to a host/hub it will not correctly specify this requirement for 500mA. This
will result in the SenseCam drawing more current than the USB host/hub expects, which
may in turn result in errors on the USB bus. This is very unlikely when connecting the
SenseCam directly to a host (i.e. in the back of a desktop or laptop computer) or when
connected to a powered USB hub. If problems are experienced when using a powered hub,
it is possible to configure the SenseCam to operate only in slow charge mode, which draws
significantly less current. This can be done using the „fast‟ BOOT.BAT command or by
altering the configuration bits (see Sections 5.4 and 5.7 respectively).
4.9. Complete power off with concealed switch
The on/off button powers down nearly all of the circuitry in the SenseCam, but it does keep
the real-time clock running (so that the camera doesn‟t lose track of time) and it maintains
the processor in a very low-power state.
If there is a special reason to switch off the SenseCam
completely then it is possible to use a small concealed
„hard‟ on/off switch which disconnects the battery and
therefore causes a complete power off. This switch is
hidden behind one of the two buzzer „grille‟ slots and must
be operated using a paper-clip (or similar). To switch the
SenseCam off, insert the end of a paperclip into the top of
slot that is nearest the front of the SenseCam and slide it
down. Similarly, to switch the camera back on insert the
paperclip at the bottom of the slot and slide it up. You
should not need to insert the paperclip more than 10mm,
and if you feel resistance make sure that you are inserting
the paperclip right at the end of correct slot.
If the SenseCam is hard power-cycled then the RTC will
be reset to 0:00:00 on 1/1/2000.
Figure 13: Hidden power switch
location.
Power switch
concealed behind
slot towards the front
of the camera