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power up an MCU using another MCU Answered

Dear all,

Here is a concept i would like to prove.
I am hoping to power up a microcontroller (MCU) using another MCU. The reason is I would like to make multiple replicates of a base circuitry and connect them to each other, two by two. The catch (what i think would be the catch) is to power up the second one using the first one. I am not sure how this would be possible!? would i be able to change the use of two i/o ports to have both the power and data RX/TX ing?
Any help is very much appreciated.

Regards,
KarimS

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gmoon

4 years ago

Provide power or just power up?

Most microcontrollers have externally triggered IRQs that will "wake up" the uC when an external signal is applied. In sleep mode, modern microcontrollers draw very little current, so this usually works better than supplying / denying power.

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karimskarimgmoon

Reply 4 years ago

Hello Gmoon,

the first circuitry needs to provide power to the second piece and keep it powered up, as long as the second piece stays physically connected to the first. i guess your comment would be valid only if i can still keep the circuits physically (and electrically) connected. please advise.

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gmoonkarimskarim

Reply 4 years ago

Hmm. Still a little fuzzy on your goals.

But, if each subsequent uC isn't connected to (or controlled by) the previous, then it would appear that no "power up" sequence is needed. It would seem that a chained "power bus" might suffice (each module would have an input and an output for power from a master source).

Have each uC module contain whatever extra circuitry to delay supplying power to the chips for a short interval, to prevent any spike damage.

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caitlinsdad

4 years ago

You have the bare +5 power available on the ardiuno but that is not switchable on/off by the arduino itself. You need to have it trigger a power transistor to feed the other arduino. The power level needs to be constant so you really wouldn't mix that with a data line.

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karimskarimcaitlinsdad

Reply 4 years ago

Thank you Dad,

No, I am not trying to mix them. However I need to power up one uC using the other, when i connect the two circuits. The reason is these uCs do not have connection to a power source until they one of them is connected to the first. It could be thought of as a chain where the first piece is powered up using a power supply, the second gets powered up when connected to the first piece, and so on and so forth for the third and fourth and...

You mentioned transistor, where do you mean it should be placed?

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caitlinsdadkarimskarim

Reply 4 years ago

Think along the lines of a motor shield or when you attach something that might draw current more than the pins can provide. It is the arduino acting like the power strip on/off button. It signals one side of a power transistor to let the power go through the other leg. You just have to figure out when the second arduino or load is attached, maybe with a physical contact switch or circuit. Good luck.