### Author Topic: How Much Current The Axon II's ADC Pins can supply?  (Read 1129 times)

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#### Mastermime

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##### How Much Current The Axon II's ADC Pins can supply?
« on: November 02, 2011, 09:55:47 PM »
Hey guys,

Does this quote from the Axon II's datasheet mean that with a total of three pins you'll be to draw up to 60 ma on what ever you're using?
Quote
Individual I/O pins can supply about ~20mA power, each. Exceeding this number could damage/fry the I/O pin.

I wasn't sure if it means the individual set of three pins or just one pin.  Also if they can only provide 60 ma, how would you connect something such as an Xbee to it because I know some of those can draw up to 200-300 ma at times.

Thanks

#### Soeren

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##### Re: How Much Current The Axon II's ADC Pins can supply?
« Reply #1 on: November 02, 2011, 10:48:04 PM »
Hi,

Does this quote from the Axon II's datasheet mean that with a total of three pins you'll be to draw up to 60 ma on what ever you're using?
Quote
Individual I/O pins can supply about ~20mA power, each. Exceeding this number could damage/fry the I/O pin.
A/D-C pins are inputs and, as such, can not supply any current at all.
Digital I/O pins, when used as outputs can supply some current - 40mA per pin for the controller in the Axon II IIRC, so the 20mA may be erring at the cautious side.

One thing is the maximum pin current, but there's also a max. for the port and one for the entire chip. None of those max. levels should be exceeded, so you cannot get the max. current/pin from all the pins concurrently.

I wasn't sure if it means the individual set of three pins or just one pin.  Also if they can only provide 60 ma, how would you connect something such as an Xbee to it because I know some of those can draw up to 200-300 ma at times.
Interfacing stuff, whether Xbees, servos or toasters running Windows only takes a very small current - the controlling signal - the power supply for the equipment comes from the controllers power supply (or a separate supply), not from the pins of the microcontroller.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Engineering is based on numbers - not adjectives

• Supreme Robot
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##### Re: How Much Current The Axon II's ADC Pins can supply?
« Reply #2 on: November 03, 2011, 12:19:31 AM »
You do not want to power *any* device using the I/O pins of a microcontroller . . . except for a LED. Or else you risk frying the pin - or maybe even the entire mcu.

The I/O should only be used for sending command/data signals, while your external device (such as Xbee) would need to be powered from the 5V and/or unregulated power buses of the Axon. The power buses can handle approximately ~13A (more details in the datasheet).

#### Mastermime

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