More Sticky?

The first community sticky has been created #,73748.0.html

What would you like for the next sticky? What questions do you find yourself answering over and over?

Some suggestions…

optiboot information…,64105.0.html

millis overflow / two’s complement arithmetic…,68349.0.html

# Thank you johnwasser, madworm, retrolefty, Graynomad, Msquare, Nick Gammon, newbee234!

Both your suggestions seem very useful.

Possible rather then optiboot specifically, a general bootloader sticky would be useful with embedded links to specific bootloader tasks one might be looking for. The problem as it stands today is that there is so much legacy information and past solutions that now have better solutions. It’s probably a much larger subject then the loop-back task, but ultimately very useful.

Millis() also could use a good one stop home to explain the why and how of proper usage. What really would be helpful in my opinion is a better example then the blink without delay sketch, one that would show two different timed events being processed independently from each other in the single sketch.

I would think a basic topic of proper wiring of simple LEDs and why a series resistor is required and how to calculate it’s size.

Another might be how to wire up simple switches using proper pull-up (internal or external) or pull-down resistors, and the why and how to handle switch contact bounce in sketches.

It’s not that these topics have not been covered in so many past posts and tutorials, but rather because of the vast spread out nature of the information, new stickies give us a chance to condense, simplify, and update the needed information so that we have a better common reference source to site for newcomers.

I’m more interested in the quality of the stickies created rather then a rush to see how many can be developed in a short time span. As we saw with the loop-back topic, it’s takes time and thought to find the the bare minimum number of steps and words that cover the topic accurately without excessive, redundant, and possibly confusing or conflicting information.


The SparkFun forums have this stickied: How To Ask Questions The Smart Way

Besides stickies it might be an idea to re-evaluate the existing sections of the forum. e.g. In the networking I see some main groups - Ethernet (shield & wifi) - XBEE - Serial

AVRdude messages would also be a nice section - or AVRtools (?)

Maybe a separate section for - school projects guidance - ? to split up the "overcrowded" project guidance a bit ;)

Just thinking out loud, Rob

The link to 'how to properly ask questions' is well and good, but it's also quite a long read.

I'm not sure that folk that 'ask' questions by stating "It doesn't work!" would read it. Just like the sticky on running a loop-back test, we could have a condensed version of it. Maybe even something like "We don't have a crystal ball, so please tell us what hardware/software you have, error messages you get, provide minimal code sample showing the error ...". Basically the same 'demands' as on, but wrapped in a bit more friendless ;-)

While we’re nominating good stickies, I’d suggest:

(how put the V1 Uno into DFU mode the “easy way”.)

One of the main things I see is the “How do I get two Arduinos to talk together” or “How do I send an integer to VB” sort of thing.

These are two similar but separate issues and unfortunately the A2A one has a lot of different answers depending on the distance/speed/etc as we know.

So while this is a common problem(s) I’m not sure a single sticky can address it, especially if we want them to be short (too long an nobody will finish reading it).

Thinks…well one of the main issues is the A2A using UART/softserial and we are always suggesting packet delimiters and coming up with some version of


Is that common enough for a tute/sticky?


  • A summary of using digital reads/writes. Why and how you use pull-up resistors.
  • Sending/receiving multiple bytes.
  • A balanced description about when to use malloc/free (please don't say "never"). Compare them to static allocation, and why one would be better than the other, and under what circumstances.
  • A bit of a discussion about the String class, mentioning possible problems with fragmented memory if you aren't careful.
  • An introduction to interrupts with some nice working examples.
  • A comparison of I2C, SPI, Serial comms. Particularly with reference to communicating between two Arduinos.

Preferably do the above without using extra libraries (other than the standard ones) because the idea is to show the technique, not just "use library X".

I would be willing to write some of those, if they were thought worthy of stickiness, and providing two or three of us don't work simultaneously on the same topic. Of course, constructive comments would be welcome.

Then we might as well have a 'Tutorials' subforum.

Proper tutorials should of course be reviewed (not in the same thread) and locked for mere mortals. Otherwise they'll get cluttered up.

Also a thing for an FAQ: how to unsubscribe -,74005.0.html - in the same area, how to edit wiki/playground ...

robtillaart: Also a thing for an FAQ: how to unsubscribe -,74005.0.html - in the same area, how to edit wiki/playground ...

That link shows me "The topic or board you are looking for appears to be either missing or off limits to you."

Seems that the thread is removed ( I'll mod my prev post asap) as my own reply (today) is not visible anymore in my own posts :(

This was the Q. There was someone subscribed to the forum, got all kinds of mail about Arduino and decided it was too much and wanted to unsubscribe the forum and didn't know how to do. Apparently he found out or found a moderator to help him out.

Regards, Rob

A sticky has to be short enough and really should be an original post that has been viewed often. (A referal from another post increase View Count, too). But I like us making “community made and approved” stickies, but better (more concicse and updated) tutorials would be fine, too.

The subject matters that I think crops up often is the ……
** **delay()** **
causing all sorts of problems for the person asking, where usually they do not realise it is the delay() and are worrying about their (il)logical program flow.

Also I see often power issues with servos, the humble switch debounce/pullup, the and incorrect explanations about millis()/micros() wrap. LED power, both the limiting resistor and getting enough mA for a bunch of them, also creeps of with frightening regularity.

A good sticky on “How to explain what you are asking” ie (1)what did you do (code/schematic) (2)what did you expect to happen and (3)what actually did happen - would also lighten my day. Stops me becoming sarcastic, just refer to the sticky.
Many, many moons ago I handling customer bug reports and the followup that they were fixed in the next version in a software company. That sequence of 3 questions did wonders for the quality of customers reports and thus enabled the programmers (they were proudly called that in thoses days, not developers) to improve the code instead of wasting time trying to understand the reports (this was before email was mainstream - question dialog was mostly snailmail). Along with the 3 questions there was a slightly longer explanation on the back and suggestions for attachments Is a good reference for serial communications that should do well to be included in a sticky on serial communications, which would get my vote for the next sticky.

How about a sticky on the subject of 9V batteries?
< grins, ducks, runs >

What’s wrong with 9V batteries?

Nothing, if your surname is Duracell

I suggest a better “blink two LEDs independently without delay()” (“PWM control to LEDs”, “Control two motors with buttons” … ) The point about the sticky being one or two short&sweet examples (we know that some people will only do cut-n-paste, brain activity is not desired, the result is). The long explanation should be in the tutorials.

(I am considering rewriting my “Avoid Using Delay” to actual cut-n-pastable code. I dont like it, but that is what the audience here craves, it seems)

What about this new arising forum-sticky (easy to find) / playground (buried knowledge, probably dated) duality ? And what about the new 'scuola' page ?

Some parts of the playground wiki contain gems that nobody can find and some parts are either outdated beyond belief or plain wrong. Maybe sticky posts should refer to the wiki and keep it more alive and up-to-date. If one is post a referrer to the wiki, it should be checked that the information is still valid.

Msquare: I suggest a better "blink two LEDs independently without delay()" ("PWM control to LEDs", "Control two motors with buttons" ... ) The point about the sticky being one or two short&sweet examples (we know that some people will only do cut-n-paste, brain activity is not desired, the result is). The long explanation should be in the tutorials.

(I am considering rewriting my "Avoid Using Delay" to actual cut-n-pastable code. I dont like it, but that is what the audience here craves, it seems)

I agree and have stated before, we could really use a "blink two LEDs independently without delay()" as the single blink without delay example doesn't illustrate the concept well enough to make the point usually being made.