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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1985
Posted: 12:02am 27 Jun 2017
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Thanks for that . At least it confirms that I am not going mad!
I had no trouble getting the data once I had realised what I got on my hands.
This chap seems to have the same "all over the place" problem that I was seeing but links that to PSU. I am powering from a separate supply so VCC shouldn't be a problem but I will check. It'll be tomorrow now as i am away on biz
cheers
FYI TassyJim:
" Came the next batch of sensors. The control board is identical, otlitsayutsya microcontroller firmware. So today there are two options "Edited by CaptainBoing 2017-06-28
erbp Senior Member Joined: 03/05/2016 Location: AustraliaPosts: 186
Posted: 02:34am 27 Jun 2017
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I had a somewhat similar problem with the Car Parking Assistant featured in Silicon Chip magazine last year. That was using the twin transducer type module that does use the Trigger signal and gives the Echo pulse width proportional to the distance, not the serial output variety. I couldn't get a stable distance reading when I had the unit installed in the garage, but every time I brought it inside to test it, it seemed fine.
Eventually I realised that in the garage I was using a USB plugpack to power the MM, inside I used the USB power from my computer. I discovered if I connected a 0.1uF cap from the +5v out of the plugpack to "real" Ground (the plugpack had only a 2 pin power plug) then it would run fine. In the meantime I had ordered another transducer on eBay, slightly different model - I'm not sure of the original transducer style, HY-SR04 I think, the replacement was HY-SRF05, it was supposed to be an upgraded version. While I was contemplating how to get a permanent connection to "real" Ground for the cap, the replacement transducer arrived, and when I swapped that one in, everything worked rock solid - and has continued to do so for over a year now. So whatever the issue (switching noise from the plugpack I guess), it was not affecting the MM, only the original transducer - the new one was immune to it. BTW, putting a cap across the + / - connections from the plugpack made NO difference - it had to connect to Ground and in fact worked equally well whether it was +5 to Gnd or - to Gnd (weird!).
I know you have a different unit, BUT maybe there is something to it being a PSU issue. Might be worth trying a different power supply just to see.
Phil.
CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1985
Posted: 03:48am 27 Jun 2017
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interesting.
When you say "real" ground do you mean the mains electrical earth connection?
I am reading a lot about these and it does seem they can be affected by noisy VCC.
erbp Senior Member Joined: 03/05/2016 Location: AustraliaPosts: 186
Posted: 08:23pm 27 Jun 2017
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Yes, mains earth.
Phil.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 08:52pm 27 Jun 2017
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I feel deep in my gut that this is going to have all kinds of unforeseen and difficult to solve problems.
I would at least first try something much simpler. You can still measure weight, but you don't have to weigh the whole bin. You could place something at the bottom of the bin that contains air or a fluid, and just measure the static pressure increase as the weight on top builds up.
From the internet I found grain weighs 0.8 grams per CC So for 1 metre depth we get 80 grams per sq cm That is about 7.84 Kpa. (roughly 1.14 psi)
I don't know how deep your bin is, but it may be several times that.
Something as simple as an old inner tube, or a large spiral of thin walled rubber tubing at the bottom of your bin and a pressure transducer could be worth a try. Grain "flows" so it should give a pretty reliable reading of the static pressure bearing down on it.Cheers, Tony.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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