This really only applies to copters since
airplane ESCs contain BECs (Battery Eliminator Circuit) to power servos. Coptors don't usually have
any servos, so the ESCs don't need to provide power for servos.
CHDK enabled Canon Powershot cameras require a 5
volt pulse in order to take a picture. Pixhawk autopilots are 3.3 volt
systems. When configured for triggering a camera by distance they
provide a 3.3 volt pulse to the signal pin you specify. Problem is, 3.3
volts won't actually trigger the camera. You need 5 volts.
By default there is no power on the power pin rail.
Only the signal pins are unique. The power and ground pins seen above
are common. If you provide 5 volts to one of the power pins, all power
pins will have 5 volts. The
Pixhawk to Canon Trigger Cable uses a
transistor to substitute the 5 volts from the power pin when 3.3 volts
is sent to the signal pin.
Check your system for 5 volts
Connect a donor servo extension to any port on the back of the
Pixhawk. Connect the red and black wires to a volt meter. Check for
5 volts. This copter shows 5 volts because it's using airplane ESCs.
Remember, the power rail is common, so if any of the ESCs have a BEC
and are providing 5 volts to the rail, the whole rail will have 5
What if I don't have 5 volts?
Then you will need to connect a
BEC to any open port on the back of the Pixhawk.
Great, so where does the end with the HXT60
connector go? Good question. Wherever you can find battery power.
Two options shown above are the copter's power
distribution board or directly to the voltage monitor. Also, many coptor
power distribution boards already have a 5 volt out. In that case you
can just run a single wire from the + 5 volt out to any power pin on the
back of the pixhawk.
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