Help deciding best way to do telemetry mods

Redbrickman · Post by **Redbrickman** » Thu Mar 08, 2012 7:02 pm

Ok I am going to do the telemetry mods soon.

I have the Smartieparts board installed.
I have the FRSKY DJT module

I want to mod the module as per Mikes instructions, but have some questions...

1 Is there anything to bear in mind if using a Smartie board and telemetry or is it just a matter of removing it temporarily and wiring to the main board?

2 What the easiest solution to the RS232 -TTL conversion board, and best place to buy (I'm in UK)?

3 I have some 32 gauge wire bought from HK and wonder is it OK to use for some of the wiring i.e. the main chip to 220 ohm resistor wiring?

4 I have read RCG thread some time ago regarding this mod, but time moves on, and others have maybe found better solutions.

5 Also when I load the FRSKY version of 9X does it limit my templates or model memory?

TIA

pldb64 · Post by **pldb64** » Fri Mar 09, 2012 4:06 am

Replace DJT with DHT and i'm in exactly the same position

I'm hoping that whoever it was that did the mods WITHOUT the need to include the RS232 steps will find the time to post some further details (ie include it in the WIKI). In following the conversation, that seems to have the most appeal.

It's either that or just wait until the ERSKY9x boards have been proved and are avaialble for general usage.

Post by **Rob Thomson** » Fri Mar 09, 2012 7:00 am

Redbrickman wrote: 1 Is there anything to bear in mind if using a Smartie board and telemetry or is it just a matter of removing it temporarily and wiring to the main board?

Simply remove the board. Wire in the new leads as per the guides. Then replace the board and re-flash with an frsky version.

Redbrickman wrote: 2 What the easiest solution to the RS232 -TTL conversion board, and best place to buy (I'm in UK)?

all solutions frskylite, max232, sparkfun follow the same procedure to install. I like the sparkfun board - but you do have to get it from usa. giant cod sometimes have the frsky lite board.

Redbrickman wrote: 3 I have some 32 gauge wire bought from HK and wonder is it OK to use for some of the wiring i.e. the main chip to 220 ohm resistor wiring?

As long as it is single core - no problem. Simply option is find an 'ide' cable from and old pc or ebay - and strip the single core wires out.

Redbrickman wrote: 4 I have read RCG thread some time ago regarding this mod, but time moves on, and others have maybe found better solutions.

There are always other solutions - but the still require re-wiring the cpu pins. the only variations tend to be a choice of serial convertor.

Redbrickman wrote: 5 Also when I load the FRSKY version of 9X does it limit my templates or model memory?

Nope. You have the same functionality - and a bit more!

Hope that helps.

Rob

Post by **Rob Thomson** » Fri Mar 09, 2012 7:02 am

pldb64 wrote:Replace DJT with DHT and i'm in exactly the same position

I'm hoping that whoever it was that did the mods WITHOUT the need to include the RS232 steps will find the time to post some further details (ie include it in the WIKI). In following the conversation, that seems to have the most appeal.

It's either that or just wait until the ERSKY9x boards have been proved and are avaialble for general usage.

Personally... the mod is not too bad without the rs232 converor. However.. you will be having to rewire direct to your rf module. This is not hard - but will require 'more' super fine soldering!

Post by **Kilrah** » Fri Mar 09, 2012 7:33 am

I will try to find the time to write up something this weekend... but the photos and my post on the other forum should already be self-explanatory to replicate the setup

The thing is, I wanted to "finish" my mod cleanly with the firmware upgrade possible before writing a detailed guide, but I'm a tad reluctant to do it on my main module in case I thrash it due to a messed up communication during flashing, and end up being unable to fly for weeks while waiting for a replacement... so I intend to order a new set first.

To those who know the upgrade system well, is there a permanent bootloader that is "crashproof" on these modules? And how often does ER9x send data to the module (alarms configuration etc)? Does it happen regularly during operation, or only on power up/model load?

Post by **ShowMaster** » Fri Mar 09, 2012 7:59 am

I built up a Turnigy 9 with a DHT DIY inside the case and use a max232 board from eBay for the rs232 conversion as posted. I tried the Frsky lite converter but messed up I guess and never got it working.
All other mods follow the telemetry writeup. I made a connector for the DHT rs232 connector by using CA to glue 2 servo connectors size by side and using a thin piece of plastic across the connectors backside. I then sanded the shell down to 4 pins. I have the servo wire and crimper for servos. I just couldn't solder to the Frsky connector supplied. Has anyone else been able to?
The only issue is finding room inside the TX case for everything and not hitting a stick back and hanging up. I did it but it's tight.
Works great and all the telemetry works. It did have a SP board bur now it's a soldered in HK programmer just to see how it works, it does.
My FlySky 9x build uses the DJT module with the internal wiring done to use the module pins for telemetry. Max232 board for rs232 and a SP programmer with wires added for controlled backlight.
Speaker mod and vibration alarm. More room without the DHT internal module.
Both setups work fine, I like the DJT module setup as my first choice.
SM

Redbrickman · Post by **Redbrickman** » Fri Mar 09, 2012 10:43 am

Thanks for replies

Rob,

I noticed on your guide written 2010 ago that you wired the 232 board onto the Smartieparts board.

Do you still recommend that or is it better to go straight onto the main board?

Another question. I have the DBR II receivers. Do they output the receiver voltage as default, or do you need to connect one of the analog ports in some way to the receiver battery?

Post by **Rob Thomson** » Fri Mar 09, 2012 10:56 am

Hello,

Guess it really depends if you use a smartie board!

If you have a smartie board - the points are nicely labeled for you to make the job easy. If not.. just go direct to the board

All FRSKY RX's I have used in the past output the RX voltage on A1 by default. Pretty sure they would be the same.

Rob

Post by **jhsa** » Fri Mar 09, 2012 11:19 am

Not all of them Rob.. the old D8R doesn't.. And the D8R II PLUS does with the help of the
little shunt connected to the "A1" and "X" pins.. I'm not sure about the D8R II

I say this because there are still some sellers on ebay selling the old D8R

Post by **Rob Thomson** » Fri Mar 09, 2012 11:46 am

Fair point. Guess I have always been 'lucky'

Post by **Kilrah** » Fri Mar 09, 2012 12:40 pm

Yep in the D8** it's only the D8RII Plus that can read the battery voltage directly. The others need the voltage sensor.

Redbrickman · Post by **Redbrickman** » Fri Mar 09, 2012 2:04 pm

Thanks guys,

Looks like I'll need to order voltage sensors then

Should have given the DBR II and Plus a bit more attention before ordering.

Just a thought though, if the receiver doesn't have the input from a voltage sensor I assume there will be no receiver low voltage warnings on the 9X?

Post by **jhsa** » Fri Mar 09, 2012 2:33 pm

I bet that the D8R-II will be discontinued soon and they will only produce the plus version as I think the only difference is that little shunt..
there's no point on selling both models

Post by **Kilrah** » Fri Mar 09, 2012 3:08 pm

Yes, they're upgrades that replace the old ones... For example my module/receiver pair I ordered 2 months ago came with a D8RII, and the latest one I received 2 weeks ago now came with a D8R-II Plus.

Post by **ShowMaster** » Mon Mar 12, 2012 3:28 am

I'm asking here because the subject on Frsky telemetry receivers came up. I have several of the DR8 ll receivers without the internal divider resistors connected from the 5 volt rail to AN1. What resistor values do I want to use to read the receiver voltage with AN1. I know it's been posted somewhere many times but I'll ask any way. What connector resistor adapter configuration has anyone found to be the smallest other than SMD. I just want it compact and rugged.
Thanks
SM

Post by **jhsa** » Mon Mar 12, 2012 3:34 am

Hi showmaster.. here, try this. It's a voltage divider calculator.. I found it usefull to calculate my resistors

http://www.linuxfocus.org/~katja/toolbo ... lator.html

João

Hexperience · Post by **Hexperience** » Tue Mar 13, 2012 10:49 pm

Hello all,

I'm a noob, and I also can't hold still. There's no chance I could solder those pins. So my question is, don't those pins already connect to some other location on the board? would there be an easier location to tap into those pins? If not, I'll have to use the external display, which is fine.

Post by **Rob Thomson** » Wed Mar 14, 2012 8:55 am

Unfortunately the only option is to solder the pins

Where in the world are you?

There is a thread with people willing to help worth mods

Sent from my iPhone using Tapatalk

Post by **ShowMaster** » Sat Mar 17, 2012 3:07 pm

I too wonder where this person is located?
Please everyone asking for help, fill in your profile. A lot more opertunities available if members are close to you.
SM

Post by **ShowMaster** » Sat Mar 17, 2012 3:29 pm

jhsa wrote:Hi showmaster.. here, try this. It's a voltage divider calculator.. I found it usefull to calculate my resistors

http://www.linuxfocus.org/~katja/toolbo ... lator.html

João

Great link, great program. I realized something using it. The 3.3k and 10k ohm divider combination you're using and Mike's telemetry 9x firmware works out just right for the newer Frsky RX's using around 13.2-3 v in the menu with wiggle room to dial it in. I think Mike mentioned this some time ago and I sort of skimmed over that but it needs to be mentioned more often. I bought some pre made dividers a year ago from Flytron that worked with my earlier d8r and 6r RX's but not with the recent versions. These dividers use a 1.1k resistor as part of the divider and give lower readout voltage. I remember that Frsky was deciding on a 1:4 or1:6 ratio divider value?
All I know is the 3.3k and 10k works with my newer RX's.
So what is the divider values and ratio of the current real Frsky divider pack on sale?
I'm asking for everyone that's confused about this and could use a current update of what to buy or build. Maybe wiki or a divider thread here if it's worthwhile?
SM

Post by **jhsa** » Sat Mar 17, 2012 3:50 pm

frsky was experimenting with internal dividers in their rx's so they've released different versions.. I know that the 6 channel receiver has different versions of the telemetry voltage input. actually, I have a couple of these receivers and don't know which dividers they have.. I think one of them has a 1:1 input but I'm not sure.. I'll have to open mine and check..

The D8R also was sold in different flavours. I can't say anything against it cos they've been listening to the people and trying to improve.. very few do that..

João

P.S. - The divider I use is 12K and 3K9.. it gives me 13.3-4 volts as maximum for a max voltage at the pin of 3.3V

SamoaFlyer · Post by **SamoaFlyer** » Sat Mar 17, 2012 9:50 pm

I’m a bit surprised that the issue of divider values keeps coming up since small, multi-turn trim pots are available on eBay for less than a buck. This allows calibration, for best accuracy, of the whole telemetry system, which includes a number of components and firmware conversions, with one simple adjustment.

There’s a way I like better, but it does take a couple more components.

Consider this: If we are measuring a battery pack (receiver or propulsion) with a simple divider, the measurement range will be 0 volts to some maximum voltage, usually greater than the maximum pack voltage. The FrSky analog-to-digital converter (ADC) is an 8-bit converter resulting in a digital range of 0 to 255. Thus the measurement resolution is equal to the range/255. For example, a range of 15 volts results in a resolution of 59mV – pretty coarse when working with lithium batteries. Also, with this input range we are using only 24% of the ADC range.

Say we want to measure a 3S LiPo. The actual range of interest is from 9.0V to 12.6V, a span of 3.6V. If we could make the full ADC range equal to this span, we could then have a resolution of about 14mV – much better

What is needed is what is commonly called an expanded range voltmeter.
Using a TL431 (cheap), a precision adjustable zener, and another trim pot, we can offset the output 0 volts point to be equivalent to any desired voltage between 2.5V and 36V, which in effect, subtracts this voltage from the pack voltage. Choosing an even number for the offset makes the mental gymnastics easier.

Calibration for the above example:
1. Initially set R2 to midrange.
2. Connect the battery pack to the divider but don’t connect the output to the receiver.
3. Using a DMM, adjust R1 for 9.00V across the TL431 (cathode to anode).
4. Set the voltage range for A1 or A2 in the er9x telemetry setup screen to 3.60V.
5. Connect the divider output to the receiver.
6. Measure the pack voltage.
7. Go to the telemetry monitor screen in er9x and adjust R2 to read the measured pack voltage minus 9.0.
Now we have an output on the telemetry monitor screen between 0 and 3.60 representing a pack voltage of 9.00 to 12.60V. Mentally adding in (becomes automatic after a little usage) the 9V offset gives the actual pack voltage with 14mV resolution and an accuracy equal to the DMM used for calibration.

The TL431 has a minimum current requirement for good regulation – about 0.5 to 1.0mA, which is determined by the value of R2. As a rule of thumb, multiply the number of lithium cells in the pack by 100 Ohms and use the closest common value on the low side. It’s not very critical. For NiMH or NiCd multiply by 30.

I realize that a lot of users only want/need a ballpark measurement so this may be overkill. For myself, I like accuracy.

Post by **ShowMaster** » Sun Mar 18, 2012 1:49 pm

Thank you for adding more exact measuring info and your circuit.
I will add this to my Frsky telemetry info folder.
This and the pot idea are good to know about. I asked the original question to get the latest ideas for divider building and got good answers. I've been using the pot idea for sometime but hadn't built up anything this year. My planes are such that ball park warnings are good enough so far. I found that fixed values and the er9x menu options get within .2 volts of my DVM vs readout do I set my alarms on the high side and land.
For those new to all this they may also want ball park values if their flying is not critical to a lower cutoff range.
Enough has now been posted to calculate values, built a pot divider, or a more precise ESV circuit.
I think all this deserves a designated place here or wiki as a place to start.
Thank you everyone for your good ideas and links.
A report on the Frsky and other premade dividers to purchase would also be a big help.
SM

ovisopa · Post by **ovisopa** » Mon May 28, 2012 5:58 pm

I started yesterday to mod my 9x using smartiepart board and Rob Thomson guide , but i couldn't find where I should wire the RS-OUT and RS-IN

ovisopa · Post by **ovisopa** » Mon May 28, 2012 6:02 pm

I get a forbidden error when I try to upload two attachments, I don't know why

Hmm it seems it doesn't allow me to add a second message with a jpg attachment, I'm getting this error :

Code: Select all

Forbidden

You don't have permission to access /forum/posting.php on this server.
Apache/2.2.15 (CentOS) Server at openrcforums.com Port 80

If anyone can help me out with a photo or another guide on where I should connect the RS out and RS IN wires I'll appreciate.

Thank you.

ovisopa · Post by **ovisopa** » Mon May 28, 2012 6:59 pm

I think I got it, on the chip side, where I removed the two resistors. Soldering now and will post a photo back

Post by **Rob Thomson** » Mon May 28, 2012 7:03 pm

If you look in my guide.. You connect to miso and mosi.

These can be seen printed on your smartie board

Sent from my iPhone using Tapatalk

ovisopa · Post by **ovisopa** » Mon May 28, 2012 11:26 pm

Thank you Rob. I was talking about the PIN6 and PIN7 in your guyde, which I connected near the CPU , on the line of the two resistors I removed.

I will attach a photo so you can see where I connected the wires. Now when I long press the down button I get the message NO DATA.
I'm with the ardupilot conected to my computer using USB, the receiver is connected to ardupilot on the first five chanels, I have calibrated the radio with ardupilot and it seems it's working ok, but no telemetry data on the screen.

SVN: er9x-r762
VERS: V1.5650-erez
DATE: 14.05.2012
MOD: FRSKY NT

Post by **Rob Thomson** » Tue May 29, 2012 6:56 am

I may be wrong.. but you seem to have a loop in place.

Your two cables from the ttl converor.. brown & red should be going to the telemetry ports on the RF module. You have looped them back to the pins on the main board?

Post by **MikeB** » Tue May 29, 2012 9:32 am

Check my reply on RCG.

Mike.

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