Pull Up/Down Resistors
Vložit
- čas přidán 23. 07. 2024
- In hardware projects, you often see resistors used alongside components like pushbuttons and transistors - Why? In this video, we explore this and also consider some possibilities this opens up!
0:00 Introduction
0:28 Floating Pins
1:36 Pull-Down Resistors
3:14 Pull-Up Resistors
4:47 Strong vs Weak Pull
5:41 Conclusion
Some more sources you may be interested in:
- learn.sparkfun.com/tutorials/...
- electronics.stackexchange.com...
-----
Want to contribute to the channel? Consider using the "Super Thanks" feature above, or visit my website at nerdfirst.net/donate to find alternative ways to donate. Thank you!
-----
Disclaimer: Please note that any information is provided on this channel in good faith, but I cannot guarantee 100% accuracy / correctness on all content. Contributors to this channel are not to be held responsible for any possible outcomes from your use of the information.
this is by far the the best description of pull up / pull down resistors i’ve come across
Hello and thank you very much for your comment! Glad you liked the video =)
BEST EXPLANATION
I HAVE A SCHOOL PROJECT RELATED TO UNO
THANK YOU FOR THE HELP!!!
You're welcome! Glad to be of help :)
I was trying to understand pull resistors for a couple of days now, thank you very much for this explanation:D
You're welcome! Very happy to be of help :)
Best explanation I’ve ever seen
Hello and thank you very much for your comment! Glad you liked the video =)
Underrated
Best video I've seen I guess
Hello and thank you very much for your comment! Glad you liked the video =)
Very helpful like it read my mind , was about to search this up after hearing pull up and pull down for so long
Hello and thank you very much for your comment! Perfect timing then, very happy to be of help =)
I must have watched a half dozen videos and gone to 2 dozen websites but watching this finally helped me understand. Thanks!
You're welcome! Very happy to be of help :)
Nice keep doing whatchu doin
Hello and thank you for your comment! Glad you liked the video :)
Great stuff! Would love to see a series on transistor configurations from you!
Love this , godspeed!
Hello and thank you very much for your comment! I happen to have a series in which I discuss how different transistor configurations can be used to build logic gates and some simple circuits. Check it out here if you like! czcams.com/play/PLJse9iV6ReqhHqCqtdoY3xnnx3DbxrxL_.html
Excellent explanation
Hello and thank you very much for your comment! Glad you liked the video :)
very good video. Thanks from Florence, Italy
You're welcome! Very happy to be of help =)
VERY NICE!
Hello and thank you very much for your comment! Glad you liked the video =)
very nice!
Hello and thank you for your comment! Glad you liked the video =)
Very nice video. Maybe you could explain how to calculate the resistor value next time. Thank you so much
Hello and thank you very much for your comment! In my (admittedly limited) understanding, the actual resistor value shouldn't matter too much.
The most critical thing to pay attention to in this setup is to ensure that there is no short circuit / excess current draw, which you can calculate using Ohm's Law - I=V÷R and ensure that I is reasonable for your setup.
The secondary impact of the resistance value is the response speed as described in the second half of the video. I'm not aware if there are any formulas that can be used to calculate the response time based on the resistance, but unless you have very specific requirements, a bit of trial and error will do.
Thanks
Excellent explanation 👌🏻
Hello and thank you very much for your comment and the super like! Very happy to have been of help =)
@@NERDfirst I've watched about 15 videos explaining pull up resistors and yours was the clearest and best explanation by far 💪🏻
@@Rees3901Gmail Same
Hi 0612 tv from N.Z. Nice to see a new video.
Hi Dave, thank you very much for your comment :)
Goated
Thank you! Glad you liked the video :)
If the wire acts like an antenna…why do random signals flowing between ground and the pin behave differently from the random signals from before (when there was no pull down resistor)? Your animation shows there’s noise on the wire either way. So how does that solve the problem?
And why does the closed switch ‘overwhelm’ the path to ground?
I believe you. I’m sure you’re right. I just would love if one of the 40 CZcams videos on this topic would take a little more time and explain the why.
Hello and thank you for your comment! These are fair points, I'll do what I can to clarify!
I'm not sure that my animation shows that there's noise on the wire - It shows an electrical connection between the pin and ground.
The kind of random noise we experience when the pin is floating comes from sources like electromagnetic induction. These are typically very low energy signals and therefore, the current generated is miniscule. When a voltage source is connected, the current generated is significantly higher. It "overwhelms" the noise by being the higher-energy source, exerting a greater "force" on the electrons in the conductor.
When we pull down to ground, all the stray currents have a low resistance path to ground, so they "drain" that way instead of registering on the microcontroller's pin.
We can use the same line of reasoning to understand why the closed switch overrides the pull-down resistor. There are two paths for the current to flow - Through the resistor to ground, or through the microcontroller pin, which has next to no resistance. Hence, most of the current flows to the pin, allowing it to register the voltage. That's what I mean by "overwhelming" the path to ground.
Let me know if this makes things clearer or if you need further clarification!
Thank you for the video. I`m building a arduino grbl cnc. I got alot of problems with limit switches, how "big" resistor should i use? Have tryed 10k with no luck.
Thank you.
Hello and thank you for your comment! I'm afraid I don't know enough about your use case to properly advise. The best I can do is to refer you to the Limit Switch page of the GRBL documentation here, I see that resistor values are given: github.com/gnea/grbl/wiki/Wiring-Limit-Switches
Thank you, that helped alot 👍And Thank you for the great video.
What the red and black points moving in your circuit means. Like I still don’t understand how voltage comes from ground to microcontroller
Hello and thank you for your comment! Don't think of this as direction of current flow (even that has two conventions and can be drawn in "both directions"). Instead, think of this as an abstraction for which is expressed "more strongly", and what the microcontroller ultimately "sees".
In reality this really is a potential divider - The voltage detected on the pin is simply the ratio of the two resistances (the latter being the miniscule resistance provided by the wire).
4:06 How can current go from ground to voltage ? Shouldn't it have gone from voltage to ground ?
Hello again! This isn't really about current direction (which in and of itself can be drawn in both ways). This is more about what's expressed "more strongly". I debated a little about making the diagram that way also, but it is the most logical way of doing it since ground is seen at the pin of the microcontroller without any resistance, so it takes precedence.
@@NERDfirst so, that means, in this configuration, there will be no current coming out from voltage because of the resistance ?
A small amount of current (_and_ voltage) will be present. However, in this context you can almost imagine it to be like a potential divider - The voltage detected by the pin is extremely low, and would certainly be interpreted by the microcontroller as LOW.