Im working on a project that has a Arduino Pro Mini built on to the PCB and i was wondering if i can just remove the reset button circuitry? I don"t see any reason why i cant but im paranoid so i just wanted to make sure its that simple.
The important bit to keep is the. 10k pull-up.
If the switch isn’t there. it means the Reset pin will be biased toward +5 which is what you want… no reset !
Ok, thanks!
One would have to wonder why.
They are so positioned as to make any "accidental operation" almost impossible for starters.
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The project im working on is a model rocket flight computer. High vibrations and tight electronic bays, i don't want it to activate on accident from lose components or vibration.
Yes it will reset, the cap C2 insures that. Starting a microprocessor with some sort of reset is a very bad design practice, it will start in some random place with random register values. Some processors have a reset built in.
Power on reset is desirable - otherwise the processor mat be in some unknown state prior to reset.
You could in theory do a manual reset every time, but the processor has self preservation in mind.
Internally, that’s handled by the cpu hardware - look at the datasheet.
Takes quite an effort to activate the button.
I would seriously doubt it would be an issue really.
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Just calling it better safe than sorry, its considered good practice in the rocketry community, a lot of commercially available flight computers don't have buttons on them.
I'd be more concerned with your layouts and methods of connections using constraints.
I've used arduino pro minis in methanol powered rc aircraft for probably 10 years or more with no signs of a reset.
More vibtation there than your rocket I'd be willing to wager.
Without a USB to Serial adapter connected to the board, the capacitor should have no effect other than acting as a very short antenna from its wiring.
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You can get really violent flights, iv had stuff rattle lose. Im also looking to fly this thing on up to an L motor so a really violent flight and not to mention if it goes into a un controlled descent. Im just not risking it.
You will need to leave C2 in place so that you can reprogram the Pro Mini if you ever need to.
You've circled three components - just remove the push button.
I suggest you keep the capacitor and rewire it to 0V so it holds the reset pin low briefly at power up, see the data sheet for the manufacturer recommendations.
Edit, sorry I was typing on a phone before, now I'm at my PC. For clarity, the capacitor should be disconnected from DTR and connected between reset and ground.
And yes, I think John Lincoln and I were probably typing at the same time.
I would not really worry about the reset button, those tiny switches typically use a dome shaped piece of metal that is pushed down by the button, requiring a reasonable amount of force to deform the metal and make contact. That is why there is typically a "click" action when one is pressed.
Maybe do Perry's suggested modification, but make it easily removeable in-case you need to reprogram.
I think Perry and I were writing our answers at the same time.
I do agree with david_2018 about the push button though.
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Unless the Pro Mini relies upon the small capacitance of the reset switch itself, I would think the reset circuit as built would be reliable, otherwise there would have been years of discussion on why Pro Mini's were not resetting reliably on power-up.
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So just remove the button?
Yes. In general, the easy thing to do in the case of a button you don't want anyone to ever press, if it is a normally open switch then remove it, leaving all other circuitry unchanged.
If it was a normally closed switch, the general solution would be to bridge the switch contacts with a wire, and remove, or don't bother, the physical switch.
Did you mean to say "without", or are you saying that a program that uses the reset button where logic might initialize and start some process over is crude design?
a7
Ok, thanks!