Thursday, June 11, 2015

100+V Arduino/AVR Microcontroller Input/Output (I/O) Pin Over-Voltage Protection Using a *Single* Resistor!

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By Gabriel Staples
Written: 11 June 2015
Last Updated: 2 Sept. 2015
Update History (newest on top):
-Added "Upfront Caveat", 2 Sept. 2015
-Added lots of extra info, & the Figures, 21 July 2015

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Here I present a pin protection method for very high and low input voltages that I learned from Atmel themselves, in their Application Note "AVR182: Zero Cross Detector."

If you've read my article titled "Arduino Power, Current, and Voltage Limitations" you know that the pin input voltage limits are as follows:
Maximum Input Voltage: Vcc + 0.5V, or +5.5V for a 5V Arduino
Minimum Input Voltage: -0.5V

However, if you simply add a single resistor in series with any input pin, you can protect it against higher or lower input voltages, with some caveats!

Ex: simply by placing a 10k resistor in series on an input pin, you get input voltage protection up to +15.5VDC and down to -10.5VDC. With a 100k resistor you get input voltage protection up to +105.5VDC, and down to -100.5VDC. Keep reading to learn more.

WARNING: 
-FOR YOUR PERSONAL SAFETY, WHEN USING THIS TECHNIQUE, I RECOMMEND THAT YOU DO NOT WORK WITH INPUT VOLTAGES GREATER THAN APPROXIMATELY 100VDC OR 20VAC UNLESS YOU KNOW WHAT YOU ARE DOING AND HAVE READ ALL OF MY WARNINGS HEREIN, INCLUDING THE ADDENDUM AT THE END OF THIS ARTICLE. 
-REGARDLESS OF WHAT INPUT VOLTAGES YOU ARE USING, YOU AND ONLY YOU ARE RESPONSIBLE FOR YOUR PERSONAL EXPERIMENTS, PRODUCTS, DESIGN DECISIONS, AND THE SAFETY OF YOU AND YOUR CUSTOMERS.

Upfront Caveat:
Though this technique may work, and be good for home-projects or quick prototyping, better techniques are recommended, especially if you are producing a commercial product. Redundancy is your friend. Using external, rated clipping diodes is certainly a better option than relying on the internal, integrated and unrated ones. For better protection techniques, including using *external* clipping diodes for redundancy, and adding transient voltage suppression, read more here: Science Prog: Using current limiting resistors on AVR I/O pins. Also see the AVR182 Application Note for references to additional sources to read in order to add extra pin protection.

Background & Concept:

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Saturday, May 9, 2015

Quick Tip: A Comprehensive List of Helpful Arduino Learning Links

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By Gabriel Staples Written: 9 May 2015
Last Updated: 9 May 2015

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Over the past couple years I have been compiling the Arduino learning links, reference pages, and resources, that I have found the most useful for my learning. I keep this list updated, and regularly add to it. The list is found at the bottom of my article titled "The Power of Arduino." Go there, scroll to the bottom, and you'll find the list.

It currently contains the following sections:


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Tuesday, March 17, 2015

Website Migrating

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By Gabriel Staples
Written: 17 March 2015
Updated: 19 March 2015

Update: As of 19 March 2015, you should no longer be seeing the redirect page below, under any circumstances, no matter where you find a link to my site (whether in this site, on another site, or on a Google search). Old links should automatically redirect to the new domain. Please notify me via the comments below this post if you still see the redirect page as shown below. Thanks!

--------------------------------------------------------------------------------------------------------------------------

I am in the process of migrating this website from http://electricrcaircraftguy.blogspot.com/ to a commercial domain: http://www.electricrcaircraftguy.com/. Please be patient as I do so. 

As you click on links, including links to my website or articles that you may find in Google searches, you may be directed to redirect pages that look like this: 


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Thursday, February 12, 2015

How To Use Basic HTML Text Formatting for Google Blogger Comments (add bold, hyperlinks, & italics to blog comments)

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By Gabriel Staples
Written: 12 Feb. 2015
Last Updated: 10 Oct. 2017
History (newest on top):
-Added links to hostinger - 10 Oct. 2017 
-Misc. updates - 21 Oct. 2016
-Major overhaul of the table formatting - 25 April 2015
-Added "entities" and additional clarification - 14 Feb. 2015
-Added screenshot of HTML-formatted comments - 21 Oct. 2016 

Other Articles:
Intro:

I've been wondering how to put hyperlinks in blog comments for quite some time now, so I finally did a little research to find out how!

Normally blog comments are plain text, but here's a sample screenshot of an HTML-formatted comment, just under this post, which I'm about to teach you how to do yourself.

Read on.

If you'd like to make your next comments at the bottom of an article a little more fancy, with hyperlinks, bold, or italics, for example, here's how!  Feel free to practice your new skills in the comments below this article too, as scratch space to test your syntax.

The following commands are accepted in Google Blogger comments:

HTML Commands ("tags"):


Command ("tag") Effect
<b>...</b> Bold text
<i>...</i> Italic text
<a href="URL">NAME</a> Creates a hyperlink named NAME, to website URL


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Saturday, February 7, 2015

Q&A: Question About Over-discharged LiPo--How do I quantify the amount of damage done to the battery pack?

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By Gabriel Staples
Written: 7 Feb 2015
Last Updated: 7 Feb 2015

Related Articles:
High-current bench-top battery test setup by FliteTest (source: 4:08)


Question I Just Received:
-from "Lakshman

"Hi Gabriel.
I am referring to your post http://electricrcaircraftguy.blogspot.sg/2014/10/restoring-over-discharged-LiPos.html#.VNXv9mSUcp0.

I accidentally discharged my battery to 2.8v/cell today due to a faulty lipo alarm. It did not go off at 3.6V while flying my tricopter and within a minute or so, the voltage dropped to 2.8v/cell. I recharged it back to 3.8v storage at 0.2A without any issues. This was before I read that article.

How do I quantify the amount of damage done to the battery pack? I usually stop flying at or before ~80% discharge. Will it be a lousier battery after this incident?

Thank you."

Here's what I had to say...


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