Ideas for Arduino Pin Protection - Static Shock

Thread Starter

iceburnhex

Joined Jun 14, 2022
19
As the title suggests, I'm looking for some methods that would best work on helping to protect an Arduino (Due more specifically) from being damaged from static shocks.

About the setup: I have an Arduino Due in a chair which is connected to many external devices using up about 14 different input pins. The issue I've ran into is that when getting in and out of the chair, sometimes a static shock can occur, and send it from the devices to the Due. The Due itself is not reachable but all the external devices which send control signals to the Due are, and I've managed to damage 2 separate Dues now. Some of the devices are just push buttons, others are joysticks, etc. The code I'm using on the Due requires Internal Pull Ups, and recognize I could probably set them to normal Inputs, and add pull up circuitry to it which may help.

Is this the only good method to help protect the Due from static shock, or is there something else I could use between the devices and the Due to help protect it?

Thanks again for any input in advance!
 

MisterBill2

Joined Jan 23, 2018
17,814
The traditional means of protecting inputs from over voltage damage has been clamp diodes. Each input has two diodes in series, connected from the power negative to the power positive so that they are revers biased. The digital input is tiedto the junction between the two diodes. If an input voltage exceeds the positive supply then the upper diode conducts and the voltage is clamped at that level If the voltage drops below the supply common then the lower diode conducts. And of course there must be a resistor in series with the input line prior to the diodes so that current through the diodes is limited. 1000 ohms is often an effective value.
The warning that goes with this scheme is that the connections to the V= and common must be adequate and low resistance.
For some applications a small capacitor, 500 PF, between the diodes junction and the power common, is also included.
 

ElectricSpidey

Joined Dec 2, 2017
2,756
Is this a gaming chair? (just curious)

Perhaps some antistatic spray might help.

And this is only a guess but perhaps some of the precautions used to protect MOS devices while working on them at a bench could help.

I'm getting a strange image of holding a grounded rod while sitting and standing. o_O
 

MisterBill2

Joined Jan 23, 2018
17,814
I have used the scheme that I described many times, and not only does it tame static charges, it also protects against battery voltage being applied to low level inputs. So it iis simple and fairly cheap.
 

Thread Starter

iceburnhex

Joined Jun 14, 2022
19
I did some looking into it and essentially came across some clamping diodes in the form of TVS, and have since incorporated that. So far its working well, I think. No issues as of yet lol. Took some time to build and wire up a schematic for the 19 pins or so I had to protect with them. Thanks for the inputs, and sorry for the late repsonse!
 

MisterBill2

Joined Jan 23, 2018
17,814
Clamping diodes have a real advantage in that they switch on and off as a basic diode function rather than an insulation breakdown function. So a clamp diode is easily good for millions of operations, while a TVS MOV device might be good for s few operations at best.
 

Thread Starter

iceburnhex

Joined Jun 14, 2022
19
Clamping diodes have a real advantage in that they switch on and off as a basic diode function rather than an insulation breakdown function. So a clamp diode is easily good for millions of operations, while a TVS MOV device might be good for s few operations at best.
Alrighty, good to know! I may have to come back to that project and swap it out when I get a chance. Thanks again.
 
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