FrSky Amp/Current Sensor.

All mods related to the frsky telemetry series of the firmware
derFrickler
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FrSky Amp/Current Sensor.

Post by derFrickler » Wed Jan 11, 2012 9:07 am

I saw that i can set the Display Unit of Voltage Sensor 1 or 2 in the er9x FrSky configuration tab to Display A instead of V.

This made me thing of using a current sensor that outputs an analog voltage instead of the voltage sensor.
After going through the er9x code i found that the "A" option was made for that, but i can't find any documentation on how to use it.

i guess:

I need a hall Sensor that outputs an analog voltage which is proportional to the measured current. (e.g. 20mV/A).
The sensors output is connected to teh receivers A1 or A2 input.
Then i set the divider in the FrSky configuration tab so that the displayed A matches the measured voltage.
My Problem here: all sensors that i know have a voltage offset, meaning they start at 0.6V or 2.5V for 0.0A.
I saw that there is some offset calculation in this part of the er9x code but i don't know how to use it.

Any hints here?


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Re: FrSky Amp/Current Sensor.

Post by MikeB » Wed Jan 11, 2012 9:45 am

Need to find time to updae the manual!
One of the telemetry display screens shows the A1 and A2 values, together with their minimum and maximum values. If the type is set to A (for Amps), then the min value is replaced by mAh used. When this screen is displayed, and you press and hold the MENU key, the offset for the A1 and/or A2 will be calculated and the displayed value will then be 0. Press and hold the EXIT key should zero the mAh field as well as the timers.

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Re: FrSky Amp/Current Sensor.

Post by derFrickler » Wed Jan 11, 2012 12:49 pm

Thanks a lot, thats what i wanted to know!

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Re: FrSky Amp/Current Sensor.

Post by derFrickler » Tue Jan 17, 2012 10:23 pm

So, i got my Current Sensor today, but i am struggling on how to get the right values shown in the 9x

Th sensor outputs 0.6V on 0Amps. Then it adds 40mV per read Amp. e.g.
0A = 0,60V
1A = 0,64V
5A = 0,80V
10A = 1,00V
50A = 2,60V
75A = 3,60V
100A = 4,60V

Is there a way to translate this to the right Amp Display? As far as i Know the inputs of the D8R-II reads 0-3,3V?

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MikeB
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Re: FrSky Amp/Current Sensor.

Post by MikeB » Tue Jan 17, 2012 11:00 pm

We may have a bit of a problem here. The code was written before FrSky came out with their current sensor. I chose to do the code to allow measurement up to a maximum of 65A, to get a good resolution. This is expecting 50mV per Amp, not 40mV.
We really need to set the ratio to 82.5A (3.3V / 0.04V) to get the scaling correct.
Since the D8R-II only measures to 3.3V, the maximum current you can actually measure, using a direct connection, is 67.5A ( (3.3-0.6) / 0.04 ). Otherwise, you would need to scale the sensor voltage down using a potential divider.
I can do a change to allow a higher scale factor, what is the maximum current you are likely to need?

In the short term, you could set the scale factor to 41.2A (or 41.3A). This should give you a display of half the actual current being measured, you will have to double it when you read it.

Mike.

Edit: Is this an official FrSky Amp sensor, where did you get it from?
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Re: FrSky Amp/Current Sensor.

Post by derFrickler » Wed Jan 18, 2012 7:26 am

Thanks Mike, that sounds great!

First of all, this is not an official FrSky Sensor (they don't have one as far as i know)
It is just an ACS758 U100 as it is used in many OSDs.
http://www.ebay.de/itm/ws/eBayISAPI.dll ... 0717394672

Now i get it with the Scaling!
Measuring 67Amps is quite enough for the moment, more important than loosing precision. On the other hand, it would make sense to protect the RX from getting more than 5V. I Would it help if i put a 3,3V Zener Diode in parallel to protect the input from higher voltages? Although i could do a voltage divider 3:1 which sould then give me 0,03V per Amp and a maximum of 90A to measure. Ratio would be 110 then?

As said, thanks for your help, i will do a small tutorial once it is running fine.

P.S. it would be perfect if the offset (which i can set in one telemetry screen, but not in the other) could be saved. Maybe one of the alarm values could be misused for that.

greets
Johannes

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Re: FrSky Amp/Current Sensor.

Post by jhsa » Wed Jan 18, 2012 7:42 am

because of those 0.6V when there's no current flowing you might have a reading different from zero on the screen.
Or is there a way of zeroing that reading??

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Re: FrSky Amp/Current Sensor.

Post by derFrickler » Wed Jan 18, 2012 9:02 am

As MikeB said:
you press and hold the MENU key, the offset for the A1 and/or A2 will be calculated and the displayed value will then be 0.
This will substract the 0.6V and display 0 then. The strange thing is that it only works in one of the telemetry screens, not in the one where A1 and A2 is shown big. If i press MENU there, it takes me to the Menu.

It would be nicer if we could use the alarm values to store the offset, as 2 alarms are not really needed for the Amp Sensor.

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Re: FrSky Amp/Current Sensor.

Post by MikeB » Wed Jan 18, 2012 9:03 am

Press and hold the MENU button when in the telemetry screen with A1 and A2 on it together with their min and max values. This calculates the required offset. At present, it is not permanently stored. I'll think if we can re-use somewhere to store it permanently.

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Re: FrSky Amp/Current Sensor.

Post by derFrickler » Wed Jan 18, 2012 5:26 pm

MikeB wrote: We really need to set the ratio to 82.5A (3.3V / 0.04V) to get the scaling correct.
Problem here, the maximum i can set is 65.0A which responds to 255 in the raw value....

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Re: FrSky Amp/Current Sensor.

Post by MikeB » Wed Jan 18, 2012 10:46 pm

I know. I need to design and implement something better. One problem is others are already using the existing scaling value. If I just change it to something else, their scaling will be wrong, and they may not realise it. I'll need a few days, at least, to sort something out. That TO DO list keeps getting longer!

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Re: FrSky Amp/Current Sensor.

Post by Mutchy » Thu Jan 19, 2012 10:32 am

MikeB wrote:Need to find time to updae the manual!
One of the telemetry display screens shows the A1 and A2 values, together with their minimum and maximum values. If the type is set to A (for Amps), then the min value is replaced by mAh used. When this screen is displayed, and you press and hold the MENU key, the offset for the A1 and/or A2 will be calculated and the displayed value will then be 0. Press and hold the EXIT key should zero the mAh field as well as the timers.

Mike.
I have just fitted a Winged Shadow How High telemetry device to an FrSky D8R -II Receiver which appears to work well. I have set it to measure in metres and by lifting the model from my bench to arms length above the bench the display changes to read "1". When I climb the stairs and hold the model high it reads "3". So it's reporting the altitude correctly in metres. But the screen under Er9x FrSky NOHT version of the firmware has a lower case "f" next to the altitude. How do I edit this screen to change this to "m"? How does one edit any of the telemetry screens in Er9x?

I have also made a voltage splitter designed to limit the voltage at A2 to less than 3.3 Volts for a 3s propulsion battery pack. I used a 1K and a 3.3K resistor to achieve 2.68 Volts when the pack voltage is 11.4 Volts. To get the display to report 11.4 Volts I have to enter 22.6 Volts in screen 9/10 at the A2 Voltage line. I would expect a value of around 14 Volts to be required. I suppose this is due to the internal existing scaling value. Is it a value of 0.5 ? What resistor value should I have used instead of 1K ? 2k? The output voltage for a pack voltage of 11.4 Volts would then have been over 3.3 Volts. Confused.....

When the first and second Telemetry reporting screen shows 11.4 Volts as the battery voltage the next screen which has all the big bold numbers shows "0.00 Volts". I guess this is a "bug" in the programme software. Anyone looking at this ? Where should it be reported?

Is there a manual or some notes of explanation regarding Er9x with FrSky Telemetry screens and how to interpret them somewhere? In the depths of the Eurgle/FlySky/Turnigy/etc Custom Firmware Facts- How to Guide Thread?

Any advice gratefully received.
Mutchy

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Re: FrSky Amp/Current Sensor.

Post by MikeB » Thu Jan 19, 2012 1:44 pm

As a general situation, we just do not have enough EEPROM to hold telemetry screen configuration data, and are very tight on flash program space to add configuration menus. This is partly why the ersky9x project is taking place, this has 250 times the EEPROM space, and 4 times the flash space.

At present, none of the telemetry screens have much in the way of customisation, that is why there are several of them to try to give a small range of options. Most of these displays have simply been created either by what the programmer think is required (Bertrand and I), or as a result of specific requests from users.

When I implemented the WS How High code (I don't have one myself), all the uses were using it to measure in feet. This seemed a good idea as it gives about three times the resolution. Consequently, er9x currently assumes the WS How High is in feet. Again, this will use up flash space and need EEPROM storage if it is to be made configurable.

When you configure the telemetry, you have 4 options for the measurement v - V and A. v is volts, - is raw data values, V is volts but doubled, A is amps.
For your requirement, you need to select v (not V). Then I would expect the voltage entry for the ratio to be about 14.1 (3.3V * (3.3K+1K) / 1K).

I'll check the third screen you mention, may be a bug, I thought it was all OK. There was an error in a recent version of one of the telemetry screens.

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Re: FrSky Amp/Current Sensor.

Post by Mutchy » Sat Jan 21, 2012 11:36 am

Thanks for your prompt reply, Mike. I understand much better now what you did when doing the programming.

I have set the HowHigh to feet. As you say , the resolution is better. It is also better for electric glider pilots because there is a dramatic increase in penalty for exceeding 200 feet on launch in F5J.

I did not realise that there were options for changing v to V and to A. I have experimented with both v and V and now have the in - built ratios sorted so that I can calculate the resistor values for voltage dividers to match the firmware.

Thanks for promising to look at that bug on the same page that the altitude is shown. It's somewhat inconvenient to look away from the model to read a screen let alone having to toggle from one screen to another.

Cheers
Steve

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Re: FrSky Amp/Current Sensor.

Post by MikeB » Sat Jan 21, 2012 2:32 pm

I think I have fixed the bug you refer too, I just can't remember which version the fix went into. It may not even have been built into a release hex file yet.

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Re: FrSky Amp/Current Sensor.

Post by chanyote66 » Mon Jan 30, 2012 5:06 pm

I recently got into the whole 9x world (since they are finally back in stock) and got my little setup below. Im still in the planning and collecting phases of equipment since i want to open the case as few times as possible.

TX (GROUND)
FS-TH9x - http://www.hobbypartz.com/79p-th9x-r9b- ... radio.html
FrSky DHT 8ch DIY - http://www.hobbyking.com/hobbyking/stor ... duct=17205
RS232 Shifter SMD - http://www.sparkfun.com/products/8780
SmartyBoard - http://www.smartieparts.com/shop/index. ... cts_id=331


RX (AIRCRAFT)
FrSky D8R-II - http://www.hobbyking.com/hobbyking/stor ... duct=14356
Voltage Sensor - http://www.flytron.com/sensors/97-volta ... metry.html
100A Ultralight Sensor - http://www.flytron.com/sensors/64-ultra ... ensor.html

This should leave my Serial connection for the FRSKY Breakout Board for VARIO or GPS.

My Questions:
1. Will this AMP Sensor work correctly? It states 1v per 20A so... 1A=.05V
2. Does anyone know how to connect a gps or vario directly to the D8R-II without the breakout board?
3. Any recommendations before I close this up? (Fixed wing powered only, no copter or glider mods needed)

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Re: FrSky Amp/Current Sensor.

Post by MikeB » Tue Jan 31, 2012 12:24 am

The maximum input voltage of the analog input to the receiver is 3.3V, so the maximum current you can measure directly is 66A (3.3V * 20A/V). This is just as well as the present version of er9x (frsky version) can only be configured to 65A anyway (close enough to 66A I reckon).

There is an NMEA version of er9x. This may handle a directly connected GPS, but I don't think it will handle the current measurement as well. You can connect the WInged Shadow How High device to the serial port. This is supported directly by the FrSky version of er9x. Otherwise you will need to get the FrSky hub and the appropriate sensors.

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Re: FrSky Amp/Current Sensor.

Post by HC1969 » Tue Jan 31, 2012 5:11 am

http://rc.emiter.hu/ (MegaSound 9X, GCL-2, FrSky-RSSI-DAC, etc.) Keress fel!

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Re: FrSky Amp/Current Sensor.

Post by ReSt » Tue Jan 31, 2012 12:34 pm

MikeB wrote:There is an NMEA version of er9x. This may handle a directly connected GPS, but I don't think it will handle the current measurement as well.
This is correct. The output of the GPS module is directly, without any manipulation/modification, sent to the ground receiver

Reinhard

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Re: FrSky Amp/Current Sensor.

Post by chanyote66 » Thu Feb 02, 2012 8:51 pm

Sounds good, ended up getting a FPV/OSD setup for the rest of data such as location, distance, altitude, speed. So ill just use my sparkfun.com 100A voltage/amp meter for the FR module. the rest will go to the OSD (even Voltage for redundancy)

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Re: FrSky Amp/Current Sensor.

Post by Clivew » Wed Jul 04, 2012 6:54 pm

The Frsky 100A sensor outputs data to the "data in" connector.
http://www.frsky-rc.com/ShowProducts.asp?id=127.
Is there any chance of Er9x support for this one?

Thanks,

Clive

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Re: FrSky Amp/Current Sensor.

Post by MikeB » Wed Jul 04, 2012 7:50 pm

Have you any idea what the data is that is transmitted when connected in this way, I haven't seen any document that describes this. If it looks like hub data, but only the voltage and current values it should just work!.

I should commit both er9s and ersky9x shortly, both with support for the current (amps) value. I still need to look at the voltage value implementation.

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Re: FrSky Amp/Current Sensor.

Post by Clivew » Wed Jul 04, 2012 8:43 pm

I'm using r763. Maybe I just haven't found the "Amps" screen, or it doesn't have one?
The FLVS-01 voltages are all there when it's connected to the current sensor, so it's
talking to the receiver Ok.

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Re: FrSky Amp/Current Sensor.

Post by MikeB » Wed Jul 04, 2012 9:17 pm

You have to configure it on the custom telemetry screen. I'm losing track slightly of what I've put in that is on the voice test version, and what is in my sources but not there. I have, however, just committed my present sources on svn, so that problem should go away. Erazz is going to do a build, then I will compare the result with my own complete build. If all looks OK, I will be able to do the build and commit myself.

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Re: FrSky Amp/Current Sensor.

Post by Kilrah » Thu Jul 05, 2012 9:14 am

It is hub data yes. I've been flying a few days with a FAS-100 and FLVS-01 connected as the last drawing shows, and an open9x build that displays current and cell info happily. Voltage is implemented as sum of the individual cells, and power is calculated and can be displayed. Not sure yet if the FAS-100 really reports a voltage of its own without the FLVS-01.

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Re: FrSky Amp/Current Sensor.

Post by jhsa » Thu Jul 05, 2012 9:36 am

well, frsky says that it needs the FLVS-01 for displaying voltage..
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Re: FrSky Amp/Current Sensor.

Post by Kilrah » Thu Jul 05, 2012 9:57 am

AFAIK the problem is that they actually don't say anything. They don't say you need it, but they don't really say you don't need it either :mrgreen:
Their Chinglish is so well written that every half sentence sends you the opposite way... after a few reads I tend for an integrated voltage sensor, but I guess the only way to know is to try and display the relevant hub frame field.

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Re: FrSky Amp/Current Sensor.

Post by derFrickler » Thu Jul 05, 2012 11:14 am

I will try that as soon as i get mine!

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Re: FrSky Amp/Current Sensor.

Post by derFrickler » Mon Jul 16, 2012 12:19 pm

Tested the FAS-100 with open9x last weekend, reading voltage and Current works fine, Power and Consumtion (mAh) are calculated by open9x.
Thanks Guys, works perfectly fine!

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Re: FrSky Amp/Current Sensor.

Post by Clivew » Mon Jul 16, 2012 10:40 pm

I second that, FAS-100 voltage reads correctly with open9x
But..I use er9x :) Mike? ;)


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