Electronics > Electronics

Confused about I/O Pins on Axon

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Mastermime:
Hi everyone,

This is supposed to add on to the 'Do I Need Resistors' topic.  Its not allowing me to post on that topic so I'm adding this one.



--- Quote ---Individual I/O pins can supply about ~20mA power, each. Exceeding this number could damage/fry the I/O pin.
--- End quote ---

I don't understand how this is true.  How could a servo be powered if this is true?  I believe I am looking at it wrong.  If someone could explain, Id greatly appreciate it.

Thanks

superfly501:
I/O pins don't power the Servo, they only give the PWM signal to tell the servo where to move, so you don't need much current for that. You would power your servo through your power source, such as batteries. Some batteries can provide up to a several amps or more. You might have to regulate your power source.

Mastermime:
Oh ok I understand.  Thank you.  So it would be fine if I powered my 12v LEDS that draw 1 amp using the unregulated section of the Axon II?  The 12 volts being supplied would be a flat 12 volts because it is being supplied from a DC-DC converter.

superfly501:
I've never used Axon II before, but I'm guessing you mean you have a 12V DC power source that is regulated to the 3.3 or 5V for the Axon II? Then I don't see any reason why you can't connect the 12V LEDs directly to the 12V source.

jkerns:

--- Quote from: Mastermime on May 22, 2012, 01:57:54 PM ---Oh ok I understand.  Thank you.  So it would be fine if I powered my 12v LEDS that draw 1 amp using the unregulated section of the Axon II?  The 12 volts being supplied would be a flat 12 volts because it is being supplied from a DC-DC converter.

--- End quote ---

OK - Servos - those have three wires. Two carry power and come directly from your power supply. And the third is a low current signal wire that gets a pulse signal from the Axon - the Axon does not supply  or sink the power - that's  why you can controll the servo directly from a low power digital output.

LEDs - these have two wires. All the current has to go through whatever is switching the LED on and off. If you connect your LED between power and the Axon the Axon would be trying to control the full amp. That is not a good thing.

If you want to control a 1 amp LED (or DC motor, or...) from a device that can only source / sink 20 milliamps, you need to use some kind of power switching device (relay, transistor) that is controlled by the Axon and will be able to handle the 1 amp from the LED.

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