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Member postings for Andy Halmshaw

Here is a list of all the postings Andy Halmshaw has made in our forums. Click on a thread name to jump to the thread.

Thread: Build your own telemetry sensors.
28/06/2020 12:02:02

Hi David, I took copies of the magazine articles and have them in PDF format if you are interested. Let me know your email address and I can email them to you.


26/05/2019 11:54:17

Hi David

I think that the flashing stars as you call them is when the telemetry data going to the Taranis changes. If the data is very stable no flash, when the value changes they flash.


26/05/2019 11:45:51

I may be able to help here.

If you go to the Telemetry screen on your Taranis transmitter and copy "Cels" (in this case) three times, then edit the first line as per the second photo. Then edit the second line as per the third photo, you will have the individual cell votages, and obviously the third line the same but inserting 3 . This will work for any number of cells in a pack (only four with Chris's telemetry module), just keep copying for the number of cells line.

You next need to edit the display page on your Taranis. Then when you long press page on your Taranis transmitter you can display your telemetry data as per the fourth photo, as you can see this is an old pack where the cells are slightly out of balance even though I use a balance charge every time.

Hope this is of help.


Photo 1


Photo 2


Photo 3



23/05/2019 09:53:09

Hi Mike,

Thank you for your post, entering the figure you had suggested helped but after experimenting I found that a figure of 1595 gave a more accurate reading. I used another meter in series and compared the readings and adjusted the number until I got the best match.


20/05/2019 11:44:11

Thanks for all the advice and help guys.

As you can see from the photo below I now have the current at zero and the VFAS voltage correct, the zero current I obtained by editing the current line in the telemetry screen on the transmitter and setting an offset value.

It may not be correct in your view but it is working and is consistent. I have added two photos of the soldering of the current sensor and leads and I feel that these are good well made connections, it may be just the combination of wire, connectors, soldering and device that gives the variation I am seeing.

You and Mike probably would have an explanation or do I have to change a value in the software so that I do not have to do the offset in the transmitter?






19/05/2019 16:27:27

Hi Chris & Mike,

Things are getting better as you will see from the photo below, I checked over the PCB to make sure there were no solder bridges and everything was okay and it was.

I noticed that I had no sensor ID so I deleted the sensor and then discovered the sensor again and it appears to be working. What is being displayed is not correct but this seems to be the zero point and when I advance the throttle it goes up by about 1.5A (no prop fitted), I just need to find out how to set this to zero. At 47A the device would be getting very hot but it is quite cold. Do I need to edit the current sensor line in my Taranis as I notice it has an "Offset " option or is something still incorrect?

You are correct Chris I do have the battery connected to the right and the ESC to the left, I notice that the VFAS voltage has come down ( not sure if this is the expected voltage). I found an error in one of the lines of code "#define RESISTOR_TO_GROUND 2700,2700,2700,2700,2700,2700" I had 2200 as the first number so was that causing part of the problem?

I would like to calibrate the device but am not sure where to take a measurement and then which line to add it into. Can you give some help here please?


I may give your values a go in the next one I build Mike and just see how they compare, as I have said this is all new to me, as the only programming I have done is GW Basic many years ago.

Thanks Andy

18/05/2019 12:17:37

Hi Chris, I have built my first Multi Function Telemetry sensor using your PCB and am chuffed to bits with the results. After reading Mikes message and remembering a problem we had at work I have left the LiPo negative wire off, it all appears to be working fine apart from the fact the Curr is reporting 0.0A. As you can see from the photo everything else looks correct.

Any help or ideas would be gratefully received and what settings to use?


Thanks Andy

06/05/2019 10:56:40

Hi Chris

I have found this Sensor Module on BangGood and EBay and was wondering if it could be used as an alternative to the ms5611. It only seems to accept 3.3V, but I do not see this as a problem as you suggest using the 3.3V Arduino. Below is the description and site link.

What do you think?


GY-BMP280-3.3 High Precision Atmospheric Pressure Sensor Module For Arduino

02/05/2019 15:06:27

Hi Chris

You are correct I do let the vario settle down after switching on and then do a reset before flying. Since mounting the Vario in a model and adding the foam it does appear to be much more stable.

Hopefully in the coming weeks the weather will get better and there might even be a chance of some thermals, it will be interesting to see the flight logs then and how stable the Vario is over a longer time.

I think I understand what you said about leaving the currect sensor off, but I am currently walking upright and hopefully as I play around and understand more I should get to the running stage!


02/05/2019 13:03:13

Below is a photo of a Alt/Vario Telemetry Sensor that I have built form the OpenXsensor web site, it is installed in an Easy Pigeon glider. Flying last night it all worked very well as you can see from the telemtry log printed. Looking forward to building up the PCB that Chris has designed and all the extra functionality it has, just waiting for some parts to arrive ( ordering from China was cheap but a mistake).

Chris how easy would it be to have a Vario/Alti/Cell telemetry without the Current sensor and can you connect the receiver lead to a Y lead to piggyback sensors?


telemetry log.jpg

22/04/2019 17:52:51

I have now put heat shrink over the unit and as advised cut the sleeving away so that the two holes are not blocked. As you can see I have added a piece of "Open Cell Foam Rubber" because on the ground it was fluctuating up and down. Did seem to help but it did still fluctuate.

Can anybody with experience say if this is normal or am I expecting too much and do you have to mount the unit horizontal or is vertical ok?

When the wind subsides and I can go flying I will see how it works in a model.


17/04/2019 18:41:34

You are right, I changed the sketch back and it worked fine. I had Said it was all new to me and I thought "A4" was referring to the pin #. I will have to try and understand the coding a little bit better.

Is there a chance you could do a schematic of the XT60 with the sensor, I think I can make out the connections from the magazine artical but it would be nice to be certain.

Thanks again for all you are doing.

17/04/2019 13:36:43

Well I have taken the bull by the horns and built my first Telemetry Sensor. The results can be seen below, all quite straight forward but I did have to change a line in "oXs.config_basic .h" before I could get it to work.

// ***** 2.1 - FrSKY data *****


As you can see from the photos it appears to be working well, just need to add the heatshrink and I should be good to go.


14/04/2019 13:18:06

Hi Chris,

You were right I used the OpenXsensor download which did not have the correct files. I have now gone to the GitHub page and then hit the Clone or Download button, everything is all there now.


14/04/2019 12:37:16

Hi Chris, when the PCBs are available I will probably go for three.

When I was working we used to get Pre Production PCBs sent to us at work in the post. These came just in an envelope with a piece of cardboard either side for protection, we never had any problems or damage to the PCBs, hope this helps.

I am totally new to Arduino but I am starting to find out how it works. When you say changing parameters do you also mean adding lines? i.e. #define ARDUINO_MEASURES_VOLTAGES YES

And the last question, the OpenXsensor sketch that I downloaded does not appear to have the oXs_config_advanced.h file! What am I missing?

13/04/2019 17:23:22

Thank you for two great articles, I have ordered some of the PCBs and am looking forward to having a go at making my own telemetry sensors.

I use 4mm banana connectors, so am hoping that I can make a V,A and Cells sensor using this type of connector, instead of having to use an adapter to connect to the XT 60 connector on the FrSKY sensor.

If you were to make the PCB that you mentioned in the article available I would be interested.

Edited By Pete B - Moderator on 13/04/2019 23:22:55

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