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Optional Controller
The Scamper robot kit uses the ComMotion PCB as a "stand alone" controller running
demonstration software however the ComMotion PCB can also be used as an I²C motor
control shield. The advantage of I²C control is that almost all of your IO pins (except A4 and A5)
are free for use with other shields, sensors or circuits.
Unfortunately most Arduino boards use a large metal USB connector that will short out many
shields including the ComMotion shield. We recommend using the
SparkFun RedBoard
or
any other compatible controller that uses a mini or micro USB connector to avoid this problem.
Troubleshooting
No Power:
Turn off the robot and check that the black wire from the battery holder is connected to the
negative battery terminal of the controller PCB. Check that the red wire from the battery holder
goes to one of the outer pins on the switch. Check that the red wire from the center pin of the
switch goes to the positive battery terminal of the controller PCB.
Turn on the switch, if the power LEDs do not light up then check all batteries have their positive
terminal pressed against the metal connector in the battery holder. Some battery brands can
be a tight fit in the battery holder. This prevents the springs from pushing the battery against
the opposite contact.
Check your batteries are fully charged and inserted the correct way around.
Motors constantly speed up and slow down again:
This indicates no signal from the encoder. Please check the encoder wiring carefully as shown
in step 15. Make sure the sensor is about 3mm (1/8th of an inch) away from the surface of the
magnetic encoder disc. Make sure the encoders are plugged into the correct header on the
controller.
Motors spin in the wrong direction:
When the robot powers up it should spin in a clockwise direction, if one or more motors are
spinning in the wrong direction then check that the motor is connected to the correct terminal
and that the wire colours match those in step 14.
Robot does not follow the line:
The IR sensor will not work in bright sunlight. If you are indoors then try closing the curtains.
Best conditions are a black line about 15-20mm wide on a light coloured floor. Check that the
sensor cable is plugged in correctly as shown in step 16.
Adjust the small potentiometer on the sensor PCB so that it is fully clockwise. If the robot still
does not work then adjust the potentiometer anti-clock wise in small increments and try again.
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