I'm new to the IoT field and want to know about IoT. For some of the questions I need clear explanations which I don't get by google search. I'm a little afraid of down votes. Is it ok to ask very basic questions here?
First off, don't be too afraid of downvotes—you gain far more rep for upvotes than you lose when you get downvoted (for questions, you get +5 for upvotes and only -2 for downvotes). However, I realise it's a bit upsetting if you see your post with a negative score, so I'm sorry about that.
Some tips to write great questions...
Read How to Ask for some useful steps to follow. In particular, make sure you're as clear as you can be when writing your question.
We don't expect anyone to write perfectly, and it's fine if you make a few grammar mistakes, but writing as accurately as you can makes it easier for others to understand you. For example, with this question, it might not be entirely clear what you're asking. Make sure you provide as much context as you can, and explain with plenty of detail.
Since your question is about the Arduino, there may be more experts at the Arduino Stack Exchange site. If you don't get a reply here, you could try removing your question and re-asking it on Arduino.
I think your particular question might also have received downvotes because it wasn't clear whether it was different from your first question. I can see that it is, since one is about Arduino and one is about STM32, but people casually reading might not notice and think that they're duplicates. You can edit those questions to make them more distinctly different, which might help.
I hope you stick around and ask some more questions, since your recent answer was quite useful. Just take a few minutes to check over your posts to make sure they're clear and easy for others to understand, and you should notice far more upvotes!
Basic questions are best if you can add enough detail in your post to show that you have done some research. This will also make it easier for people answering your question to pitch their answer at roughly the right level. There is a difference between a badly asked question, and a very basic question.