Reset Multiple Uno cards with one switch

I am brand new to Arduino hardware. I have developed a prototype for the city museum for a display. It will require 10-12 Uno cards that need to be reset at the same time. Can I parallel the switches to one master switch? Required: pullup resistors, diodes? Anybody done this? Diagrams? BTW, this is fully volunteer work - not for profit.

Thanks!

Yes. The reset-input has a 10K pull-up resistor and the reset switch is grounded so it "overpowers" the resistor.

If you wire 10 in parallel you'll have 1K of pull-up resistance and any one of the built-in reset switches, or an external switch, will reset them all.

I'd use a switch to GND and a diode to each RESET input.

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Thanks, I was thinking along those lines. Have you tried it? I would hate to fry a dozen boards.
:slight_smile:

IMPORTANT: All boards must be connected to the same Ground .

I would connect a diode (eg 1n4148) in series with each reset line. Anode to the reset lines. Cathode to a 10k pullup, switch to ground.

Reasoning: The diode will stop one board reset from resetting all the others. It may not be needed it the perfect case but will be very helpful if there are issues and you have to troubleshoot which board is going awry .

Thanks, so a general purpose diode to each of the reset pins and a 10K limiting resistor to ground? Sounds about right. I really appreciate the info.

I wouldn't use a 1N4001 - 1N4004. The 1N4148 is pretty common and I know using it will not get you into trouble.

Cool, thanks for the heads up. Sorry Radio Shack is out of businesss :slight_smile:

You can simply power them down then when wanted turn on the power. You could do this with an arduino, I would use something in the 12V range and power the Vin on each with a SEPIC or Buck converter putting out about 8 volts. If they are on the same circuit maybe you can just cycle the breaker. Just trying to keep it simple.

Thanks, it's for a museum display and I volunteered to help out. I think I have a great starting point with the suggestions on the diodes and the 10K resistor. I have used similar arrangements with 4055 logic circuits (I am that old :slight_smile: ). I will post wiring diagrams of a proven working circuit, unless I get smoke :slight_smile:

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There is no need nor use for a pulldown resistor. Reset is an active LOW input.

If the boards are reset by an Arduino output then a transistor and current limiting resistor may be required for draining all the capacitors on the Reset inputs. No such extra components are required if a mechanical switch is used.

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The purpose of the 10K was as a Pull UP. The goal is to keep the diodes cathodes high when the switch is open. I don't like floating circuits.

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My concern was:

You won't get smoke experimenting with the reset pin.

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I think that may have a problem with a well regulated power supply, it may not be "instant" enough. I will try it though. Thanks

Yes, this worked but after the power supply, not the mains. Thanks!

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