boojumliussnark
@boojumliussnark@lemmy.world
- Comment on Current limiting 1 week ago:
I got the 30 amp. My thought was that the motor uses up to around 20 watts when running so a little more than 1 amp, and as far as I can tell, it tries to pull around 6-10 amps(!) when stalled/almost stalled. I think this should mean a fairly large spike, that I should be able to detect even with the 30A device.
But of course it is probably just absurd overkill, and will make my life more complicated. Fortunately they are absurdly cheap and easy to buy, so if the resolution turns out to be a problem, I can get another range, when I have some empirical data. The other ranges should plug in, in the same place right?
- Comment on Current limiting 1 week ago:
Thanks again!
Does this look OK, to your trained eye then? Image
- Comment on Current limiting 1 week ago:
Thanks. It has been fun, both doing the software, where I feel at home, but also the challenge of trying to do electronics, where I am completely lost :D You can’t imagine the amount of DC converters I have burnt out, or my absolute confusion why I couldn’t turn a motor on and off using a couple of relays! I must confess I still don’t understand, but at least now I know.
- Comment on Current limiting 1 week ago:
Sorry I forgot to ask: I should cut the SENSE-A connection to ground right?
- Comment on Current limiting 1 week ago:
Oh, wow!
Very nice! Thank you so much for doing this!
Is it correctly understood that the “Sense” line can be hooked up directly to the ADC input on the Pico?
Now, just because I am quite ignorant when it comes to all this, I will venture to ask: This is better because it is closer/faster/more exact than using the Hall current sensor, or? With my complete lack of understanding, I had the impression, that I could more or less “just” connect the sensor to the “right spots” and directly to the ADC input on the Pico, and my work in the Pico would be similar to this setup?
Don’t get me wrong - I can see this is much more elegant - and won’t be bothered by whatever else might use power on the same rail. But since it might be simpler for me to use a more “out of the box” component like the sensor, instead of my bad soldering of several discrete components… Also however ridiculous it might seem it is much easier for me to source 5 modules - than 5 of each of these components (I would have to buy many of each, and waste most).
So I have to ask. :-)
- Comment on Current limiting 1 week ago:
OK… I understand very little of this :( I am a software person. But could this comparison not be done with some hysteresis? The part count is not important as long as the parts aren’t terribly expensive, since this is exclusively for my personal use.
- Comment on Current limiting 1 week ago:
It is a networked window opener/closer for my house, all with parts sourced from China, since the commercially available openers are very overpriced IMHO. Which I guess also speaks a lot to the fact that I am a man with more time than money…
- Comment on Current limiting 1 week ago:
That sounds very cool - and way beyond my own understanding :-)
Is this something you could actually help with sketching out for me?
I found the datasheet for the L298 and I can see that for my use (I am using just out 1 and out 2) it should be pin 1 (Sense A) that should be relevant, right?
This looks like it is connected to gnd on the driver board (I can easily cut this connection).
Unfortunately I don’t understand what a current shunt is? :-)
It has me slightly worried that it says that pin 1 can go to -1v which I think would break the ADC input?
As far as I can tell the ADC input on the PICO accepts from 0 - 3.3v right?
Thanks a bunch for looking at this!
- Comment on Current limiting 1 week ago:
Ah… Since I am not a smart man, I have already invested too much (for the project) in several of these motor drivers. :-(
- Comment on Current limiting 1 week ago:
Thanks for taking time to look at this! :)
The issue is that if something is blocking the motor, or the limit sensor is not working, the motor should stop before burning itself out or breaking stuff.
I did buy a hall effect current sensor (www.aliexpress.com/item/1005006222090940.html) that I was thinking of connecting to the pi pico on an interrupt enabled pin, so I could cut off the engine output at the source, and alert my upstream controller. But I just couldn’t wrap my head around how to implement it.
Another option that I considered was putting some kind of fuse on the 18v rail and try to figure out how to detect if the 18v rail was dead and feed that to the pico - but then I’m not really sure how much simpler (if at all) that would be.
The picos inputs are 3.3v btw.
- Submitted 1 week ago to askelectronics@discuss.tchncs.de | 22 comments
