level shifters

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pdieken
 
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level shifters

Post by pdieken »

Do you have a simple eazy to use shifter that would allow me to run my arduino uno off of the gpio pins on my pi? Or if there are other suggestions on how to resolve this problem.

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adafruit_support_mike
 
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Re: level shifters

Post by adafruit_support_mike »

A RasPi's GPIO pins can't deliver enough current to run an Arduino. Each pin is limited to 8mA, and there's a 50mA limit for all active GPIO pins.

The 5v pins aren't technically GPIO pins because their value never changes. You can power an Arduino from one of those.

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pdieken
 
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Re: level shifters

Post by pdieken »

yes I am doing that now but i want to arduino to only be powered up when the Pi is booted up and running and he 5v pins are always on when the pi is plugged in weather it is booted up and running or not. if i wasn't a such a complete idiot on programing the pi itself to run the same thing that the uno is i could bypass the uno altogether. but i am beating my head against a wall trying to figure it out.

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adafruit_support_mike
 
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Re: level shifters

Post by adafruit_support_mike »

The easiest solution is to build a switch into the line that supplies power to the RasPi and shut everything off at once. You'll probably need to cycle power to reboot the RasPi anyway, and a RasPi in power-down mode still draws current (about 100mA IIRC).

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