ATtiny25V wake up from current

Hi! I am goint to experiment with a ATtiny25V controlling another device with a NPN transistor basically. I am going to control it periodically so I am going to enter sleep mode and later wake up with the watchdog timer.

The thing is that the device that I am going to control also have a main power switch, when waking up I need to be able to detect if there is any current drawn, if not then I need to enter sleep mode and when current is detected again wake up.

I guess I need to wake it up on pin state change but don't know how to do this based on if there is current drawn or not. I need this to be cheap and tiny, I don't need any accuracy at all measuring current I just need to detect if there is current being drawn if that makes sense. What components should I be looking at? It needs to handle up to 60 V 5A.

Hope I described my question well enough to let you understand what I want.

*Edit: I wonder if I could use a hall effect sensor? Perhaps for going to sleep but tricky to wake up I guess. For waking up it would require something to be powered from the device being controlled and be able to work in a wide range of different voltages, anything passive that can manage to do this?

*Edit2: To summarize my question: Is there a passive (or parasitic) way to wake up my microcontroller when the main power switches back on and that device begins to draw power?

The ATtiny25V can wake from various Sleep Modes via the Int0 pin and via a Pin Change.

There are various ways to detect current, and generate an ATtiny25V compatible interrupt signal. BUT more information is needed:

  • 60V AC or DC?
  • Minimum current trip point?
  • What voltage will you be running your ATtiny25V at?
  • And, a schematic would be nice, otherwise any attempt to give you an answer will be a shot in the dark.
  • Also, it would help to know what you're running with that 60V -- otherwise this has the potential for being an "xy problem" -- see How To Use This Forum

If the thing being switched is the main power for whatever the thing it's talking to, can you get onto the supply after that switch? If so, then you can just look for voltage, which is easier.

I refreshed my memory about the X-Y problem and think I got it explained enough to avoid this but I will try to elaborate further. I’m not to familiar with all the technical terms and such but I’ll do my best to describe what I want to do and hopefully you understand what I need and can point me in the right direction. I don’t want anyone to explain to me exactly what I should do but if someone can give me an idea of direction and perhaps some components to have a closer look at that would be great!

I didn’t think the requirements thru the first time, 24 V DC is enough for my intended application. Minimum current trip point would be low, is lower than 0.05 amps possible? I will be running the ATtiny25V at 3 V, my initial idea was at a lower voltage but since I decided for 3 V I can use the other variant I guess. First I was planning on stepping up voltage from a AAA battery but that was before I realized what an incredible bad idea it would be to mix batteries of different capacities together in series. I was planning on putting 2 x AA batteries in series with one AAA battery (because of space limitations) to power another device and use the one AAA battery to power my device, that was before I knew how it worked and what would happen. It’s not to hard to get that I am a complete rookie from those last sentences :).

I don’t have anything close to a schematic right now because it would be too much of a shot in the dark for me I believe, I really think I have to try and learn much more before I try and put a circuit together. Perhaps it’s necessary that I do have something to show for you to understand what I need?

The device will be controlling other devices power by interrupting the wire from the power supply to the unit, powering of and on after a schedule. At first since the current is low I thought a transistor would be the best but perhaps a mosfet would be more suitable? Although perhaps I need something that is normally closed, I have a hard time wrapping my head around this.

Since you already understand that I am a absolute complete rookie I will keep you on that track, it’s just that I had an idea I wanted to explore. I was reading about “open-circuit voltage” and that led me to the conclusion that since my device would be after the power supply and before the main power switch this would apply but since the main power switch will break the circuit there wouldn’t be any voltage right? I really need to start tinkering and read more basic stuff, I understand some of this is really basic stuff, but I also want to understand what components to look closer at.

Thanks for answering, that’s awesome!

Jaman42: I didn't think the requirements thru the first time, 24 V DC is enough for my intended application.

So, there is an intended application. Any chance we can know what that is? Otherwise xy is still a possibility.

Jaman42: Minimum current trip point would be low, is lower than 0.05 amps possible?

So, if the max current is still 6A, that's quite a range! Difficult to deal with when sensing current.

Jaman42: I will be running the ATtiny25V at 3 V,

Cool.

Jaman42: I decided for 3 V I can use the other variant I guess.

What other variant?

Jaman42: I don't have anything close to a schematic right now. Perhaps it's necessary that I do have something to show for you to understand what I need?

Then, it seems like you're not ready for the kind of assistance this forum was designed for. It's not practical for us to teach you electronics, here.

Jaman42: The device will be controlling other devices power by interrupting the wire from the power supply to the unit, powering of and on after a schedule.

This is why we need to hear more about your intended application. Otherwise, it's difficult to fathom what you're talking about, here. For instance: "The Device"? Do you mean the one being powered by 24V? Or are you talking about the ATtiny? What other devices? "Power Supply"? Is that the 24V supply? "Powering of[sic] and on after a schedule"? A schedule provided by the ATtiny? See? Confusion.

Jaman42: At first since the current is low I thought a transistor would be the best but perhaps a mosfet would be more suitable?

Wait. I thought the maximum possible current was 6A? That's not "low".

Jaman42: Although perhaps I need something that is normally closed, I have a hard time wrapping my head around this.

And I have a hard time advising you on this, because of the lack of a vision of any of this.

Jaman42: I was reading about "open-circuit voltage" and that led me to the conclusion that since my device would be after the power supply and before the main power switch this would apply but since the main power switch will break the circuit there wouldn't be any voltage right?

I can offer this: When a power switch opens, the voltage appears across the switch. That's a concept that takes some getting used to, and requires a period of study and visceral experience.

Jaman42: I really need to start tinkering and read more basic stuff,

yes you do ;)

Jaman42: I understand some of this is really basic stuff, but I also want to understand what components to look closer at.

Then, you probably need to go do some more study, and come back with specific questions.

I don't think my description was that vague and I already know that I don't know much about electronics. I asked if something was possible and for guidance on what components to look closer at. I never asked for a solution or for you to teach me electronics.

If you feel you can't do that with the information I provided thats fine but I was fairly informative in my question and don't really think I deserved the answer I got but that's fine I guess.

Jaman42: I don't think my description was that vague and I already know that I don't know much about electronics. I asked if something was possible and for guidance on what components to look closer at. I never asked for a solution or for you to teach me electronics.

If you feel you can't do that with the information I provided thats fine but I was fairly informative in my question and don't really think I deserved the answer I got but that's fine I guess.

OK...Yes, it is possible to generate a signal, from an intermittent current, that can be used to wake an Arduino.

Thank you, that answers half of my question in a kind of a smirky way. For the remaining half I am going to find out for myself because the excitement I felt initially when posting is getting drained here.

If I had 50 years of experience in electronics and a rookie showed interest in my field of expertise I would use my expertise to try and supply an informative answer, like "Yes, it is possible but it is difficult to deal with this wide range when sensing current, have a look at [component name] that can be used together with [component name] in a setup to generate the signal.

You are extremely superior to me in this area and I know with your 50 years of experience that you could point me in the right direction on what components that could be used. Instead you focus on the details like I were to point out that you wrote "Arduino" instead of ATtiny, I know what you meant, it's just feels kind of pointless when I already explained that "I don't want anyone to explain to me exactly what I should do but if someone can give me an idea of direction and perhaps some components to have a closer look at that would be great".

You have the right to answer the way you want to off course I was just hoping for something more constructive.

Jaman42: You are extremely superior to me in this area and I know with your 50 years of experience that you could point me in the right direction on what components that could be used. Instead you focus on the details like I were to point out that you wrote "Arduino" instead of ATtiny, I know what you meant, it's just feels kind of pointless when I already explained that "I don't want anyone to explain to me exactly what I should do but if someone can give me an idea of direction and perhaps some components to have a closer look at that would be great".

Sorry if I sounded "superior". I truly was trying to help. And the only way to get to any such "have a look at [component name] that can be used together with [component name]", I needed the extra information I requested. Also, I truly was confused by some of what you wrote, and was attempting to tease out more clarity -- not everyone get's my humor ;)

In most cases, requirements drive choices such as circuit configuration, and component selection. Which means, it's unreasonable to expect such offerings, based on so little information [or inability to discern content that supposedly contains said information].

Also, writing is a "one-dimensional" mode of communication, and often "tone" gets lost, and thus misinterpreted. In other words, it's easy to hear snark, or impatience, or dismissal, etc, in text that had no such original intent. Also, consider that putting receptiveness before pride, will open greater learning vistas ;)

Also #2, consider there's a world of detail beyond your current purview, such that you might not even know, what you don't know. And, that's not a dig, but merely a reality of inexperience. We've all been there. And, next to some of the experts that answer questions, here, I'm still there [especially those well versed in SwitchMode, RF and other such esoteric disciplines]!

But, you have the right idea about the "tone" of my response in post #6 -- I suppose it could be called "smirky". My mental-scape sounded like "Well, let's see if stark brevity teases out an admission of wanting more! Bam!!" -- so, in that one case: Guilty :P

I might be a tad impatient and frustrated about my lack of knowledge in this field and probably put up unreasonable expectations on what to get back with the information I supplied.

Thank you for trying to help and for a good and educational answer. I will go and learn some of the basics to get a better understanding and if I come back, I will come back with some schematics and a more detailed question.