More than 6s lipo?

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RightRudder
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More than 6s lipo?

Post by RightRudder » Fri Dec 16, 2016 7:52 pm

Now that there are many people running large electric systems I was thinking about the limitation of having only 6 analog inputs on oXs. Two of the analog port pins are already taken for I2C with pressure sensors leaving only 6 analog inputs. If a current sensor is used then it means one can't deal with cells monitoring on a 6s pack anymore and the next option is only 4s. Would it be possible to add support to use 4 digital pins to drive a CD74HC4067 16 channel mux? That would allow up to 16S to be read sequentially on one A/D pin.

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jhsa
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Re: More than 6s lipo?

Post by jhsa » Fri Dec 16, 2016 9:50 pm

Use a second arduino and connect it to the first over I2C as another sensor??? If you are going to power such a big bird that takes 6 cells or more, than the weight and space from the other arduino is nothing :)

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Re: More than 6s lipo?

Post by mstrens » Sat Dec 17, 2016 8:14 am

The easiest is to use several oXs on the same SPort. Just take care a different device ID for the voltage fields on each oXs.

Otherwise, I think that someone already adds an external ADC communicating with arduino via I2C. In that case, it does not use extra Arduino pins and it provides greater accuracy because it uses a better ADC (e.g. 12 bits instead of 10 bits). You can find more info somewhere on this forum.

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jhsa
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Re: More than 6s lipo?

Post by jhsa » Sat Dec 17, 2016 9:42 am

I did think about the ADC before I posted, but the extra arduino might be actually cheaper, and you gain more digital pins as well.. That is why I mentioned it :)
I don't use S.port. I like more the Hub protocol because I find the D8 equipment much more reliable than the new X stuff. Never had a single problem with my D stuff, and don't remember reading about people that had problems apart from damaged antennas. Not the case with the X equipment unfortunately. Also no messing with updating the firmware. I hope they keep it in the market longer.
So, no, I cannot do the different sensor ID rain dance, also ersky9x doesn't allow for this I think, and for me that is a minor detail actually.. :)
But this is me, of course :D

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RightRudder
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Re: More than 6s lipo?

Post by RightRudder » Sat Dec 17, 2016 3:02 pm

Did you know people are running 6s on theOxy 3 heli? That is not a big bird at all and some people count grams when building. In many cases you are right 6s and up is found on really big stuff but when you consider that for a given power, the current drops as you go to higher voltage so there can be a weight savings on smaller copper wires and bulky connectors and your battery capacity can be lower as well. However I am building my own hardware so I could just as easily add another processor instead of a mux. The FTDI programming header becomes a problem but I could put some jumpers in to select the processor. I could program using a ZIF socket as I do for the bootloader but I like to leave the potential for tweaking the FW later on if something interesting comes up. It does seem like overkill to run two whole processors just to get some extra I/O, in this case only one extra analog pin!


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jhsa
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Re: More than 6s lipo?

Post by jhsa » Sat Dec 17, 2016 3:08 pm

Things could be made to suit different needs.. That has been what oXs is from the beginning, right?? :)

Some of my models use only battery voltage and current.. A complete arduino is certainly overkill :) But as you say, later the same sensor could be used in another model, or even add more features to that same model.. We never know :)

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Re: More than 6s lipo?

Post by MikeB » Sat Dec 17, 2016 4:58 pm

jhsa wrote:So, no, I cannot do the different sensor ID rain dance, also ersky9x doesn't allow for this I think
I just looked and I do have some code in to handle 2 FLVSS devices, although I think there was a bug in it so it didn't work properly.
With the bug fixed, ersky9x should handle 2 FLVSS sensors, as long as the first is on it's (correct) physical ID of 01. Then up to 12 cells are monitored with the total voltage and lowest cell available as telemetry values. At the moment, only the first 6 cells are available to display individually.

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jhsa
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Re: More than 6s lipo?

Post by jhsa » Sat Dec 17, 2016 5:01 pm

Thanks Mike. What about 2 oXs sensors? that'd be interesting :)
I for example build all my sensors..

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MikeB
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Re: More than 6s lipo?

Post by MikeB » Sat Dec 17, 2016 8:48 pm

If the first is on physical ID 01, and the second on a different ID, then they should appear like two FLVSS sensors and so work (provided you have firmware with the bug I mentioned fixed!).

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Kilrah
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Re: More than 6s lipo?

Post by Kilrah » Sat Dec 17, 2016 9:15 pm

Only for X/Sport though. Jhsa said he was using D gear only, that doesn't work there.

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Re: More than 6s lipo?

Post by MikeB » Sat Dec 17, 2016 9:23 pm

Hmm, the 'D' hub protocol still has a 4-bit field for the cell number, so, it should be possible to accept cell numbers up to 12.
ersky9x does currently limit it to 6, but it would be a small change to allow up to 12.

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jhsa
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Re: More than 6s lipo?

Post by jhsa » Sat Dec 17, 2016 9:49 pm

That would be great Mike, specially if it worked with the hub protocol..

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