Dynamic memory allocation in microcontroller programming

Today in the lab we look at why dynamic allocation of memory in constrained memory environments is bad. The most common example is the use of the String C library. Lets discuss the Arduino memory structure, look at the difference between the heap and the stack, what can go wrong, and how it can be avoided!

= Channel Stuff =================================================================

Lab Coat up, we are going to learn something today.
This channel is an all-out assault on ignorance, and you are our projection of force.
Through this channel we are going to make stuff, we are going to break stuff and we are going to test stuff

= Sister Channel ================================================================

If you interested in all things fishing, please check out our sister channel!

Fishing For the rest of us

= Tags =========================================================================
#Maker #Strings #Arduino

[KevinSidwar]

Is that shirt "I'm not arguing that with you"? Favorite scene from Joe vs the Volcano. Great job.

[BillyGriffiths]

Came across your video in an attempt to better understand memory allocation. Great explanation! I now understand the problems I’m facing a whole lot better! Thanks!!!

[theshiv]

This exact problem I was facing Man I was too lazy and using strings but now I know I am gonna change my code now

[Wesley-Insley-Comedy]

I've got a mechanic/engineer friend who would love this channel. I'll point him your way :)

[capistor]

This was so helpful. I am hoping to build an actual product and knowing that memory could be corrupted so easily was an eye opener. I will certainly apply whatever I've learnt here in my project. thanks again. do more of these please.

[the-creative-block]

I'm going to be totally honest with you: I have NO IDEA what you're talking about BUT. i LOVE the energy that you bring to your content and your educational approach to your niche is really well presented. Killer, man!!!

[cipstechitips]

I am new to Arduinos. Thanks for the explanation. I do not understand it fully, but it does help greatly to understand my "Low memory problem". I am now using the Serial.println(F(… gets back to a safe level. I know I need to get a better understanding of pointers and char arrays. Cheers.

[farukhannan]

came here for memory allocation, got hungry instead :) . Nice video though

[ivanrodionov]

Firstly, outstandingly clear explanation! I was however a bit confused by what exactly is the meaning of ' String resp = ""; '. If I understood correctly, "String" is some sort of special arduino c operator that creates an array on the heap, sort of of like an arduino malloc?
Also, the 'char resp[200]; ' is essentially allocating a 200*(however big a char is) bits of memory for that array on the stack right?
If so, would there be a difference between the ' String resp=""; ' and say 'char resp[];' ?

[sgdingman]

I have a problem with my UNO giving me the " Low memory available, stability problems may occur." message after I recently tried to add the ability to save my data to a micro-SD card. I had to include both the SPI.h, and the SD.h libraries to my sketch. So my sketch would upload OK, but wouldn't return any data. So in pursuit of a solution, I happened upon your video. I watched it on the edge of my chair since In my sketch I included a form of the error that you have pointed out here. I'm not really sure if making corrections that you spoke of in this video will help me solve this particular issue that I'm presently facing, but you sure have given me some food for thought. Thank you so much.

[linengmiao]

"all the globals end up in the data segment" 2:20. What are your sources? if I am not mistaken global variables are allocated on the .bss memory segment. Hence they are always automatically initialized at zero

[skipperz]

spirntf is not fully linked to my arduino uno. %f does not work
is it even possible to get it to work with sprintf OR do i need to look for other methods to solve this issue.
my code - sprintf(T, "temp = %f hum = %f", temp, hum);
where T is a char Array

[SebastianDylag]

This is just way to hard for me to even try to understand haha
Congrats almost 800 subs ! ;D