I'm having some issues understanding the Watchdog timer and interrupts for the ATtiny85. Basically, I just want to be able to blink an LED a couple times, then go to sleep for 8 seconds (which I guess is the longest the watchdog can run for?), then wake up and do it again. Later I would like to be able to sleep for longer periods of time, but I have no idea how that could be done either. I have already read through dozens of forums and articles about this stuff, but none of it really makes sense, I'm pretty new to this sort of thing, so the info is a bit overwhelming. Any input on either of these issues would be great.
Thanks
~Josh
Interesting. So the question I have is: does the Watchdog timer run when the MCU is put to sleep. I have no idea... But, I do have the 328p datasheet... In section 10.5 it said, "Watchdog continue operating (if enabled)". So that was the wrong MCU, but also my level of interest ... good luck.
Yes, the watchdog can run while the rest is sleeping, it has to be enabled just like the 328. I know that what I'm trying to do is possible, and actually fairly basic, I simply don't know how to do it.
Thanks
This project uses t85, takes a temp reading, goes to sleep, wakes and takes another, compares, and lights a tri-color LED to indicate the direction of temp...
http://www.hackster.io/rayburne/hot-yet
Ray
Take a look here:
ATtiny85 sleep mode, wake on pin change interrupt or watchdog timer (6,66 µA)
gammon.com.au/forum/?id=11497&reply=6#reply6
Later I would like to be able to sleep for longer periods of time, but I have no idea how that could be done either.
You simply have the MPU wake up with the selected watchdog period, increment a counter, and if the counter has not reached a selected maximum, go back to sleep. If it has, blink the LED etc., set the counter back to zero, and go back to sleep.
Arbitrary sleep periods can be programmed this way, in integer multiples of whatever watchdog period you have selected.
mrburnette:
This project uses t85, takes a temp reading, goes to sleep, wakes and takes another, compares, and lights a tri-color LED to indicate the direction of temp...http://www.hackster.io/rayburne/hot-yet
Ray
I appreciate the suggestion, but in the intro of the project, he specifically says 'I consider this an advanced project and not suitable for newbies.' I happen to be one of those newbies, so a lot of this goes over my head unfortunately.
Josh_Blackburn:
I appreciate the suggestion, but in the intro of the project, he specifically says 'I consider this an advanced project and not suitable for newbies.' I happen to be one of those newbies, so a lot of this goes over my head unfortunately.
As I am the author, I'm suggesting that if you are already messin' with the watchdog that you might as well learn how to do it correctly.
The techniques used are from several authors combined... Gammon, Codingbadly, etc.
I think you can, based upon your problems, understand why the article was marked "advanced." These techniques are simply not middle-of-the-road techniques for newbies. That is, they create a support nightmare when used by someone not understanding what they are doing. Still, Arduino is a learning experience and the code is well-documented. Take the plunge.
Ray