I am building a spirits still control using the Mega 2560. I have the control working and I am now focusing on error detection and
diagnoses of problems. I would like to use the watchdog timer and will set it at a very long time, such as 8 seconds. Distilling booze is a very slooow process!
I have seen a number of threads that indicate there are potential problems with this feature on the Mega 2560. I can't say that I understand the issues, although it appears one problem is caused by using a very short time-out period. This should not be a problem for me. Are there other problems I could run into and is there any general advice you can give me regarding the use of the WDT instructions?
What do you expect the watchdog timer to do, if it does off? Most attempts to use the watchdog are misguided. Make sure that you are using the proper tool for the job, first. While a hammer will gets screws into wood, it isn't usually the proper tool.
Good question. I would like to signal the operator that something is wrong with Arduino control so that he can switch to a manual mode in which the batch can be completed or safely aborted. I haven't looked at how this can best be done, because I didn't want to waste my time figuring it out only to find out the Mega 2560 has an issue.
Its also very illegal in most parts of the world (ALL ENGLISH SPEAKING PARTS OF THE WORLD and all of Europe) with out the right permissions and if you are heat distilling, very very dangerous.
An output to be connected to the MCU RST.In the normal situation,to feeds it every once in a while.If within the prescribed time, no "dog".Then the watchdog will give a signal to the RST MCU to let the MCU resetoration.
I still have not received an answer to my question. Does the watchdog timer work properly on the Mega 2560.
There are a number of threads indicating it has a problem, and then I see indications the problem has been solved, or it is ok
with some limitations. I don't trust my ability to find all the threads on this subject. Is there someone out there who
can tell me what the "bottom line" is on this issue?
Mark, do you assume everyone you don't know is an idiot?
I am an electrical engineer working on a control for a licensed micro-distillery.
Against my advice, the owner wants to use the Arduino instead of a PLC, so I have looked for potential problems.
I have found quit a few threads indicating the Mega 2560 has issues with the watchdog timer, and some indicating
that later versions may be fixed. I was hoping someone could answer my question. I suspect the answer is something like "it is ok to use it for------------------------, but don't use it for--------------------------------."
You clearly don't know the answer.
• Barry asks a question with too much context (the Arduino boards are about inputs and outputs and event processing etc…).
• Mark (too busy and/or impatient) missed the question regarding alleged posts about WATCHDOOG feature problems, yet having time to write an irrelevant but insulting answer.
• Barry attempts to focus and rephrases the question
• Mark, still irritated fails to answer WATCHDOG question, but instead shows us his law expertize
• Bla, bla, bla
• Now, let me try (as I do not make illegal substances)….
Mark, it is not the first time something ATMEL made had an issue (or anybody else for that matter). Are YOU AWARE of any issues regarding WATCHDOG “mechanism” with Arduino Mega 2560 ?
In short, yes, the watchdog works fine if you implement it properly.
The only issue I’m aware of is after a reset, the boot loader fiddles with the restart status bits, and you can’t determine after the restart whether the reset was a cold start or a watchdog/brownout.
I believe there are code patches to address that issue, but the hardware works fine.
In the 7 years since the original posts I hope the OP found a suitable answer to his question. There were issues with older bootloaders and the watchdog timer, not sure at what point that was addressed.
The bootloader can indeed throw spanners in the wheel. A WDT timeout that is too short (I think below 2 seconds) will keep on resetting the bootloader and you can't upload via the bootloader; fix is to burn the bootloader (via ICSP) after which you can upload again via the bootloader. I recently helped somebody who had the issue on an Arduino Mega.
You can also get rid of the bootloader by burning the sketch via ICSP. If that does not solve the problem, you have found a bug in the chip But I don't think anybody here has found that problem.
But I don't think anybody here has found that problem.