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Rx battery telemetry ???

Posted: Thu Jul 18, 2013 12:34 pm
by Steve71
Sorry if I sound a bit stupid here.......but on trying the set up the Rx battery power telemetry, the system used.......doesn't make much sense ?.

I want to be able to see what's left in my various gliders flight packs, on screen.

Most are using 4.8v packs, and one is using a 6v pack.

I tried setting it up, but got differing figures on different models...........do I need sensors plugged into my D4R-II and D8R-II Plus Rx's.

Thanks,

Steve.

Re: Rx battery telemetry ???

Posted: Thu Jul 18, 2013 12:41 pm
by Kilrah
There are no stupid questions, but... you're not telling what you're using to display the value (FLD-02? DHT-U? Modified 9x? Smartphone app? PC?), so there's no way to answer it ;)

Re: Rx battery telemetry ???

Posted: Thu Jul 18, 2013 12:45 pm
by gohsthb
It is posted in the Taranis forum, I would assume he is using a Taranis.

Re: Rx battery telemetry ???

Posted: Thu Jul 18, 2013 12:50 pm
by Kilrah
Makes sense, didn't see where this was posted...

No sensor needed on the D4R-II, jumper needed on the D8RII-Plus between A1 and X, and A1 range set to 13.2V on the telemtry page (it is by default). That's all there is to it :)

Re: Rx battery telemetry ???

Posted: Fri Jul 19, 2013 9:43 am
by Steve71
Hi guys.....

Sorry for not mentioning, but yes......my shiny new Tx is the Taranis X9D.

Thanks for putting me right, OpenTx is all very new to me..........it took me around 24 hours to program in 17 various models (not all in one go, I must add !!).

I looked at what you mentioned, and all is OK now.

Many thanks again.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 1:50 pm
by Redbrickman
My Taranis is due to arrive next week :) . Just wondered if the 8XR receiver has a built in function to output the battery voltage? At the moment I use D8RII receivers with my 9x and voltage divider boards but never thought to check before ordering the 8XR if it has the telemetry function built in to the receiver?

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 2:21 pm
by jhsa
with that receiver alone you can only monitor the receiver voltage.. no Analog ports.. pretty useless at this point, at least for me.. :(

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 2:25 pm
by MikeB
At the moment the only way to monitor a motor power pack with the X8R is to use the SPort versions of the FAS40 or FAS100.

Mike.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 3:44 pm
by Redbrickman
Bummer :( especially since I have gotten used to the telemetry being available on my existing receivers. Seems like a backward step for Frsky, and after taking a quick look at the FAS40 it seems it still requires a voltage sensor of the type I am using with my D8RII receivers.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 4:12 pm
by MikeB
No, the FAS40 and FAS100 send battery voltage as well as current. On er9x, in the list of telemetry items, the current is "Amps" and the voltage is "FasV". I'm using a FAS100 to a D8R-II and don't need a voltage sensor as well.

Biggest problem is I don't think FrSky have got their SPort enabled sensors to the shops yet.

I agree that the lack of a analog input is a backward step.

Mike.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 4:19 pm
by Redbrickman
Thanks for info Mike, probably buy a Fas then as I wouldn't want to fly without telemetry alarms for the model lipo.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 4:21 pm
by MikeB
It needs to be a SPort version, or you need the SPort Vario as well. The SPort Vario will 'bridge' from the hub serial data to SPort mode.

Mike.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 5:13 pm
by Flaps 30
Looks like many will be better off using the older RX's with analogue voltage inputs for now.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 7:07 pm
by jhsa
There has been many people sxaying they would like to have the analog ports back on the receivers.. Maybe frsky takes that in consideration ;)

João

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 8:47 pm
by ShowMaster
A simple poll early on a few forums would tell them so much ahead of a product redesign. I'm sure the new rec design when all the interface devices and sensors are finally available will be nice, but it's the months or more waiting for them that's not.
No way to simply monitor onboard motor lipo's? Maybe this was designed as a glider/sailplane system as many have been posting? If the 9XR only analog input was like the d8R ll+ it would have taken care of more battery monitoring choices. So simple to add the jumper option you would think.
As with others, I have now 9XR receivers I don't use and went back to the D series until there are better options.
I don't have room for all the extra sensors and hubs required in my favorite planes.
When will the X8R+ be released with the added jumper for the A1 port?
Good rumor to start.
That or the DIY hack to add the option to the current X8Rs?
I'm game to try a mod but could use some ideas on the best way to do it.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 9:10 pm
by Kilrah
The lack of analog port being a problem was mentioned to them, along with a solution to add it without requiring hardware changes, so I would guess it's intentional...
Regarding polls it's rarely a good thing. When you start asking you get so much things going in all directions that it's impossible to settle on something...

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Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 9:21 pm
by MikeB
I don't think we've seen any circuit of the X8R anywhere. Personally I'd prefer an analog input to the RSSI output.

Mike.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 9:35 pm
by ShowMaster
Thanks Kilrah I sort of guessed it was to sell more sensors and I don't mind. They sell it we buy it, pretty good system for us all!
It's just that it's like only selling one warm glove and not a pair of them. It's a great idea but one hand is still cold.
I'm also thinking that Frsky had many here sign a NDA that in the past would have torn into the x8r already and added a mod to use the A1 port for other voltage options. If I'm correct we've lost some great creative minds that we've come to depend on. So new minds will have to tear into this and post their ideas. Maybe Frsky will step up their sensor releases and save us all the trouble!
You can't buy it if it isn't for sale! All that $ not being spent by me.
That my gripe, money and no product to spend it on!

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 10:25 pm
by MikeB
Just poked a 'scope probe around inside a X8R. It has a STM32F103CB processor. Running from a NiMh battery measuring 5.2 volts I found pin 16 has 1.31 volts on it. This is a possible analog input to the processor, and corresponds to a 4:1 divide ratio. I can't see any tracks going to pin 16, it must go back under the processor. I haven't looked further so I don't know know where that voltage is coming from. Maybe someone else would like to look further?

Mike.

Re: Rx battery telemetry ???

Posted: Thu Sep 05, 2013 11:11 pm
by ShowMaster
It's a start Mike thanks.
I may risk it with the rec I have with the antenna paddles. It's not going in a plane for some time yet.

Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 1:10 pm
by Kilrah
The rssi out pin is an analog input to the mcu and the circuit appears to be analog compatible, so knowing that the vast majority of people will never need rssi I suggested that we could choose with a jumper or something if we wanted that plug to be analog in or rssi out. Wasn't considered unfortunately.

I personally think the reason is that there have been soooo many people confused by the adc reading, division ratios etc that they were fed up with the questions and decided to go all digital so that it's plug and play.

Still think they should have done like I suggested.

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Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 3:11 pm
by ShowMaster
Either pin Kilrah would do. I've never had a range issue but having it monitored is a nice feature. I think making the A1 I'll call it, available for other analog inputs would be my vote. When I'm flying nitro I would like to know my rec pack voltage. Electric and lipo, monitor the lipo.
So how to free up the needed pins for either input is the challenge.

Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 7:54 pm
by MikeB
Just done a bit more investigation on the X8R. On the opposite side of the PCB to the processor are two resistors R16 nd R15. I measured tham as 4.5K and 1.5K, and they appear to be a potential divider on the supply pins. So a 4:1 divider using 0402 SM resistors.

Mike.

Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 9:00 pm
by ShowMaster
Where do you get time to do so much Mike?
So if the combination allows 13v max input for 3.3v out IC I did the math right?
Change the 4.5k to 7.5K for 20v in max?
Does if look like the trace can be cut to free the top end of the 4.5k?

Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 10:09 pm
by MikeB
I couldn't see the trace clearly, I need to put it under the microscope!
Just checked for power rating. A 0402 resistor might be rated as low as 63mW, however, 4.5k needs over 15V across it to get to 63mW so, power wise, it is safe for an input voltage of 20V, but 13.2V to meet the 3.3V input requirement.

Maybe the easiest mod would be to remove the 4.5k resistor and add a new resistor (wire ended) with one end to the original resistor pad and the other end brought out to a suitable connection.

Mike.

Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 11:04 pm
by jhsa
The problem is that we would be modifying the a part of the RF system. The question is, would we still be insured in case of an accident? (knock on wood :o )

João

Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 11:09 pm
by ShowMaster
I agree that removing the 4.5k could give the solder pad needed to bring the wires out. That and a ground. I have the microscope and a USB endoscope camera if it cools off I'll have a look.

Re: Rx battery telemetry ???

Posted: Fri Sep 06, 2013 11:11 pm
by MikeB
I'll post this here as it seems related to me. I have a production XJT module running in a 9X. I'm currently routing the X8R battery value to A1. I notice that it is reading low.
Checking with the Taranis I see the same low reading with the internal XJT to another X8R.
The A1 value shows 4.8V (jumping to 4.7V occasionally) when the actual measured value is 4.97.
The Taranis shows 4.81V when the actual measured value is 4.97.

I don't think the Taranis has any calibration value to correct this.

Mike.

Re: Rx battery telemetry ???

Posted: Sat Sep 07, 2013 1:05 am
by ShowMaster
Rats! I got as far as trying to separate the boards and was afraid I’d break them. I assume those are connectors and not soldiered? Got any pictures of what you’re doing? If there is no provision to compensate the readings then it becomes more complicated.

Re: Rx battery telemetry ???

Posted: Sat Sep 07, 2013 6:13 am
by Kilrah
MikeB wrote: I don't think the Taranis has any calibration value to correct this.
The A1 range setting is done just the same way as on a 9x and can compensate for it.

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