The people who do give out code tends to be younger people - very often students who have just recently managed to fight themselves through a similar exercise. Giving out the code seems to be some form of personal fullfillment - see I am good enough to write this code.

But, the posted code tends very often to be of limited quality. The harder it was to write (the closer it was to the competence limit), the more likely it is to be posted. And the posters tends to post any code that is within a mile of the request. The requester often have to spend a huge amount of time trying to get the code to function - just to notice that the code did something completely different.

As people get older, we tend to spend more time asking "why". Not all problems are meant to be solved. There are often other alternatives that are much better. We don't look as much at problems as "challenges" but instead at what would be an efficient or reliable solution to a problem. And one of the requirements for a developer to ship a reliable solution is that the developer do understand their solution. This requirement to understand means that copy-paste code tends to not be applicable. If you need to understand the code, then you may just as well write it yourself. The need to understand exists for commercial projects, where a failure will cost a lot of money. But it also exists for school projects - how to you turn in a school exercise if you can't answer any questions the teacher may ask?

If you download code from some web site somewhere - check if that site has a system of voting for good code. That may improve your chance of getting code by a competent developer. If you visit a forum and get 5 different implementations posted directly, you should be very worried. That is not a good sign. And even if you download sample code from manufacturers pages, you have to be aware that the person who wrote the code may not have any real experience writing embedded software. It may be a hw engineer. Or a practicant. Maybe someone who is good at handling support cases but lousy at coding.

So in the end, there will very seldom be any free lunches. The normal way is to either spend own time, or spending money buy hiring someone who is skilled in the required area. Of course, not all consultants are worth their fees, so even there it's a question about checking references.