Husqvarna Automower 305 Technical Manual page 53

5.1.2 Circuit boards
There are three circuit boards in the robotic
lawnmower:
• Main circuit board (1)
• MMI circuit board (2)
• Front sensor card (3)
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The circuit boards contain the electronics and
software required to control the mower's functions.
In simple terms this can be described as the main
circuit board gathering sensor signals that are
evaluated by the software and generating control
signals for the motors. The MMI circuit board collects
its information from keys that are pressed on the
keypad and conveys the menu selections that the
user has made to the main circuit board, which saves
them in its memory. These selections subsequently
become the conditions for the main circuit board to
take into account in evaluating the sensor signals.
The MMI circuit board also has the task of presenting
information from the main circuit board to the display.
The main circuit board and the MMI circuit board
contain their own separate software. If any of these
cards are replaced, they have to be programmed via
Autocheck EXP.
A new MMI circuit board contains software but, after
being fitted, it must always be programmed to be
updated to latest version.
The front sensor card does not have any software,
and consequently does not need to be programmed
after a replacement.
5. REPAIR INSTRUCTIONS
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3020-019
5.1.3 Sensors
The robotic lawnmower is equipped with the following
sensors:
• Collision sensor (1)
• Tilt sensor (2)
• Lift sensor (3)
• Rear loop sensor (4)
• Front loop sensor (5)
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The lift sensor and front loop sensor are mounted on
their own circuit board in the front part of the chassis'
lower section. The other sensors are mounted on the
main circuit board in the lower section of the chassis.
The sensors cannot be repaired. If troubleshooting
shows that one of the sensors is defective, the entire
main circuit board or front sensor card (depending on
which sensor is defective) must be replaced.
The front and rear loop sensors measure the signals
that the circuit board in the charging station transmits
in the boundary wire (A signal), the guide wire (guide
signal) and the charging station (F signal). The
signals are used to steer the mower and keep the
mower inside the working area.
The lift sensor and the collision sensor measure
the magnetic field from the two permanent magnets
that are located in the body. If the magnetic field
decreases (the distance to the magnet increases) the
main circuit board interprets it that a lift or collision
has occurred.
The tilt sensor is an accelerometer positioned on the
main circuit board. It measures the gradient in both X
and Y axis. The value is used, among other things, to
correct the speed of the drive wheels when mowing
on steep slopes.
The current value from the sensors can be read in
the display on the mower, as well as in Autocheck
EXP.
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1
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3020-020
English - 51