FrSky XJT COMM1 Used With DHT on COMM2

[kiwihornplayer]

I currently have my FrSky DIY internal DHT module connected via COMM2 using Pads 7.8.9. This works fine on its own with the switching and I have telemetry enabled and working via the B & W cable going to 9XTreme FrSky socket.

I want to add a new XJT external module which will take over the FrSky 9XTreme socket and require some direction to reroute the DHT telemetry data via COMM 2.

First of all the obvious question – is one of the spare pads already set up for this?

As each COMM port switches on or off through the Model Setup menu does it matter if the active module shares the FrSky connector with the inactive module?

[MikeB]

You should be able to use COM1 with both modules, as the module not in use is powered off.
I would add a 1K resistor in the Tx data from the DHT, but then just connect this signal and the SPort signal (from pin 5, bottom pin, of the module connector) together and to the COM1 connection.

COM2 on this board does not have any buffers, it is logic level, so cannot be connected directly to either telemetry signal, it would need bufering and inverting.

Mike.

[jhsa]

what about if someone wants to have both modules ON for more channels? Both modules would be sending telemetry, right? And you wouldn't be able to turn the telemetry from one of them OFF, I guess?? That would mess things up..
What about a little level converter on COM2 then?

João

[bob195558]

Mike, I am hoping to have two FrSky transmitters ON and choosing which one I want to have telemetry
with (D-series sensors or S.Port sensor) like I am using with my erSky9x on Taranis.
(viewtopic.php?f=7&t=4582&start=360#p99734)
I could use the flexible ability to set an XJT internal transmitter with an XJT external transmitter to PPM or PXX
and so to choose which one uses D or S telemetry sensors.

Will 9Xtreme have the same ability's ?

Bob B.

[MikeB]

Bob: It should be possible. The only constraint/problem is the COM2 connection is 3.3V, logic level and so would need an inverter/buffer to handle the telemetry input(s).

We tried to limit the amount of "extras" on the 9Xtreme to keep the cost low for the majority of users.

Mike.

[jhsa]

Mike, as I asked above, wouldn't a level converter like the one we use for the frsky mod work? I would guess many of us already have them..

Thanks

João

[MikeB]

As long as it outputs 0-3.3V it should work fine.

Mike.

[jhsa]

And if it outputs 5V maybe a voltage divider would help? Of course? Testing needed

João

[bob195558]

I am not sure what I would need.
Would Any of these work ?
(http://www.ebay.com/sch/i.html?poi=&adp ... 8709619960)
(http://www.ebay.com/sch/i.html?_nkw=3.3v+5v+converter)

Bob B.

[kiwihornplayer]

Thanks Steven and MikeB for a great product.

The interface between 9Xtreme, DHT Internal Module, and XJT External Module is real neat. The single black wire to XJT pin 5 and on to DHT with 1k resistor works fine. The switching interface is great.

I love the menu binding for XJT.

The only comment I would make on the telemetry interface is that data font size on the user configurable telemetry screens is just a tad too large - especially if using all 6 positions. With the ability to set up voice alarms for these functions the need to visually monitor them constantly is not so important. Something for future development perhaps?

Thanks again guys.

[jhsa]

As far as I know that there will be smaller letters and numbers soon

João

[jhsa]

Bob: It should be possible. The only constraint/problem is the COM2 connection is 3.3V, logic level and so would need an inverter/buffer to handle the telemetry input(s).

We tried to limit the amount of "extras" on the 9Xtreme to keep the cost low for the majority of users.

Mike.

I was just thinking about this.. I'm not sure it is good to be cutting costs in this case. The reason is only the DHT modules that were heavily modded (RS232 circuit removed) will be able to connect directly to this COM port. That could lead people that didn't do the mods to the DHT to misread the posts of people that did it and connect their unmodified modules directly to the port, probably destroying the CPU?

João

[s_mack]

I'm not sure "cutting costs" is a fair evaluation, any more than saying we cut costs by not including blue tooth or haptic. It isn't like a corner was cut but, rather, a feature was not added. I kept to my design goal from the beginning: any feature which we implement is to be fully implemented as much as possible; any forseeable features that are left off will be given board space (ie. "holes") for the end user to connect to at their effort, cost and risk. A DHT is by its very definition a hack module. It needs to be carefully integrated into WHATEVER you're integrating it into... in this case a 9Xtreme. It is up to the user to know what they are doing. Of course any guides can and should alert the user to pitfalls... but the target here was the much easier to install/use DJT/XJT and that's what the design intent was.

We can't protect everything from everything/one. Nor can we forsee every eventual piece of hardware someone may wish to connect. Be it a DHT or a toaster... if a conversion is need to safely interface, that's on the user to sort that before flipping the switch.

[jhsa]

I'm not sure "cutting costs" is a fair evaluation, any more than saying we cut costs by not including blue tooth or haptic. It isn't like a corner was cut but, rather, a feature was not added.

I used the wrong expression and I do apologize. I didn't mean to say it that way.. Mike did say "keeping the cost down to the end user" which is not quite the same

I kept to my design goal from the beginning: any feature which we implement is to be fully implemented as much as possible; any forseeable features that are left off will be given board space (ie. "holes") for the end user to connect to at their effort, cost and risk.

Well, the 9xtreme as far as I know is supposed to support an internal RF module, right? It even has a switching power circuitry for this internal module. The only internal module that I know that can output telemetry is the DHT. This outputs RS232 serial on it's serial port. I would say that by reading the problems people are having with setting up their system, which is not a problem with the system, but the lack of knowledge most of the times, probably 80% won't know that a level converter of some type is needed in order to connect a DHT safely to the 9Xtreme's COM 2. From those 80% (I'm guessing of course), probably 40% don't even know what a level converter is. This could have a disastrous outcome. I believe that at least this subject will need a warning in big letters on your website

A DHT is by its very definition a hack module. It needs to be carefully integrated into WHATEVER you're integrating it into... in this case a 9Xtreme. It is up to the user to know what they are doing. Of course any guides can and should alert the user to pitfalls... but the target here was the much easier to install/use DJT/XJT and that's what the design intent was.

It is called hack module because it can be installed inside a transmitter that supports it. It does not mean that you can cut very small tracks, and do some fine soldering to eliminate the RS232 circuitry and tap the 3.3V serial signal. This will invalidate your club's insurance in many places anyway. Let me mention again that the 9Xtreme does have an internal switched power RF module connection, CONTROLLED by the PROTOCOL menu, and it is not for a DJT as it is not an internal module and it outputs RS232 levels anyway.
So, what was the design intent when an internal switched powered circuit, controlled by the protocol menu in the radio was implemented?? Not for the DJT, correct? nor the XJT?
There are 3 COM ports available, right? only one (COM1) is RS232 tolerant, correct? So, is there another internal module available and supported by ersky9x that outputs logic level serial telemetry?? I can't think of one
Oh wait, found one The DIY Multiprotocol Module.. Of course, you would have to build it yourself, Hmmmmmmm...

We can't protect everything from everything/one. Nor can we forsee every eventual piece of hardware someone may wish to connect. Be it a DHT or a toaster... if a conversion is need to safely interface, that's on the user to sort that before flipping the switch.

Ok, fair enough from a business person point of view I think it would be safer to connect a toaster directly to COM2 than the DHT.
I hope I'm wrong, but if a RS232 signal directly connected to the 9Xtreme can destroy at least part of the CPU, we will see some destroyed boards in the future.. This is my opinion of course.
As I said above, I think a big warning with big letters should be in order.

DO NOT CONNECT A DHT MODULE DIRECTLY TO THE INTERNAL COM2 OF THE 9XTREME. YOU NEED TO INTERNALLY MODIFY THE DHT MODULE OR ADD SOME EXTERNAL CIRCUITRY (whatever that circuitry is). FAILING TO DO SO CAN DESTROY YOUR FRESHLY INSTALLED PRIDE AND JOY, THE 9XTREME BOARD, OR EVEN CAUSE A NUCLEAR MELTDOWN ON YOUR NEAREST POWER PLANT.
ALSO, CONNECT TOASTERS, OR ANY OTHER HOUSEHOLD APPLIANCES TO THE BOARD AT YOUR OWN RISK..

João

[s_mack]

I'm not saying we didn't design it with the DHT in mind... of course we did (well, Mike did - I've actually never seen a DHT). I was just trying to explain the "costs" bit. *IF* what you're suggesting is correct and a stock DHT module attached will damage something - It sounded like you were only guessing - then absolutely a warning should be provided and it should be addressed in the next batch - either by providing the necessary circuitry or eliminating support... whatever is necessary to prevent that situation from being a likely outcome.

The 9Xtreme is a means for accessing advanced firmware, for plugging a DJT/XJT module into for telemetry, for getting voice and a cool backlight. Past that, it offers connectivity for advanced users to mod in various ways, and that includes the DHT. Still, obviously I don't want a situation where people doing something seemingly logical end up with poof.

But one step at a time... is this really even a concern. Mike? Spell it out for me please

[jhsa]

Wow, I can see that you live near a nuclear power plant Don't be afraid, I was joking But the toaster bit still applies

I was just saying that a warning where everyone would for sure see it (your website) would probably be enough. Well, we have to read your website to buy the board, right?
You don't even have to mention the DHT. Maybe just saying that any internal RF module with telemetry must output logic levels and not RS232 levels.

No need to eliminate support for it. Just a little warning where erybody can see it.

João
EDIT: I could be wrong, but for example on the Megasound voice module such a circuit takes only a couple transistors, a couple resistors and a diode or two. Nothing very expensive? Of course there are dedicated ICs for this task but I don't think they are expensive either?

[MikeB]

The 9Xtreme only has the one 'spare' COM port. The design allows both internal and external modules to share the first COM port (that is buffered with inverters), and you only need to use COM2 for telemetry if you want BOTH modules powered together. You can only use the telemetry from one of them at a time anyway.

The second COM port may be used for telemetry, in which case you need to add inverters, but you may want to use it for a bluetooth HC-05/6 (still needs adding to the firmware), in which case you don't want inverters.
So choosing to fit inverters or not, on COM2, was always going to be "wrong" for some users.

Mike.

[jhsa]

Wait a second, are you saying that if we have an internal module that is also capable of sending telemetry, we can't connect a bluetooth module?

So, for example this situation, internal DHT with frsky telemetry, and external DSM module with telemetry. We wouldn't be able to connect a bluetooth module without losing the telemetry on one of the modules?
I really thought this board had 3 COM ports like the other boards
Oh well, I could install a DHT internally, connect it to COM 1, and connect the BT to COM 2. But then I can't connect any other module with telemetry to the external module bay and I would like to use my DJT for some of my models as in my experience it has better range than any of the DHTs I have. If I do so, I lose the ability of having Bluetooth.
Making my DIY module internal is also out of question. Bummer
Can we tap a third COM port somewhere, or the CPU does not support it?
João

[MikeB]

No, I said both internal and external modules can share COM1, so you don't need COM2 for telemetry.
You only have a problem if you want both modules powered at the same time.

Mike.

[jhsa]

Yep.. that would be the case for having 16 channels with 2 D modules.. I think this is the big reason to be able to use 2 modules at the same time? Even 2 XJT for 32 channels max? I don't use X Gear and don't plan to though..

João

[jhsa]

This has the same processor as the taranis, right? As far as I know the taranis can use both modules and still has a COM port in the battery bay?

João

[jhsa]

So, I have a couple radios that have 3 COM ports available, but no switched power to any of them
I thought the 9Xtreme would fix this as it has the switched power for the modules. But it turns out it only has 2 COM ports. That completely throws away the reason why I bought one and was going to make it my main radio. RGB backlight is very nice to have but it is not essential to fly my models. So, there is not really an advantage over my current Ersky9x radios.
We can never have it all, can we?
I want to make it clear that it is NOT your fault. You guys did a GREAT job and this board will make many people happy.
I BLAME MYSELF for not doing my homework or at least have asked some questions before.
So, now excuse me but I'm going to my corner, put my donkey hat ON and sob for a while

João

[MikeB]

No, the Taranis cannot use two modules (both powered) and have the serial port available. Two XJT modules "collide" on the SPort, you cannot disable the telemetry from one of them. A DJT in the module bay may be used, but either collides with the internal XJT (if wired to the SPort), or uses the serial port in the battery bay.

The 9Xtreme uses the same processor as the Taranis, but with fewer pins.

I'm sure we can come up with some solutions, it will likely just need some extra hardware. What we have is very useable for most users as it is.

Your main problem is, I think wanting to use TWO modules, both with telemetry AND powered at the same time, without using COM2?

Mike.

[jhsa]

I thought of a hack that could save the world, well at least mine.. I swapped hats by mistake and ended up wearing my "Thinking Hat" ON instead of the "Donkey hat with big ears".

Mike, you're implementing an arduino for the rotary encoder, extra switches, etc, right?
As we won't use telemetry on both modules at the same time, would it be possible with the help of the arduino and a couple MOSFETs switch the telemetry to COM 1 between the 2 modules? If not possible with mosfets, maybe with something else? even Reed relays?
We would need an option on the protocol menu, or maybe better, the telemetry menu.
This would allow us to connect both modules to COM1 and have both modules ON if necessary. It would leave COM 2 free for the bluetooth module. No hacks to any of the RF modules needed. Everybody win as far as I understand??

Thanks

João

EDIT: if Mosfets don't work, would some optocouplers do the job?

[jhsa]

I'm sure we can come up with some solutions, it will likely just need some extra hardware. What we have is very useable for most users as it is.

Your main problem is, I think wanting to use TWO modules, both with telemetry AND powered at the same time, without using COM2?

Mike.

Thanks Mike, please see my last post
I think bob195558 would also like that idea very much
Thank you for trying to find a solution. Maybe Steven could even incorporate it on the next batch

João

[bob195558]

Hi João, Mike and everyone,

The XJT module can be used as a DJT by setting DipSW 1 ON & 2 OFF/ PPM/D8.

I hope to add an XJT module internally, by purchasing an XJT module, taking it out of it module case
and installing it internally in my 9Xtreme radio.

I would like to have the ability to have both transmitters (modules) powered at the same time
and be able to choose which one dose telemetry.
And with each XJT transmitter (Internal and External) whether to use D-series sensors (in PPM or PXX)
or use the X-series sensors (PXX).

May need to use Com2 with an added inverter to be able to choose telemetry between the XJT transmitters.
I will need help with finding a proper inverter and how connect it up.

Maybe could add an additional switch to select between which XJT transmitter uses the Com 1 telemetry wires ?

Also could the stock 9x board be used for additional com ports ?

With my Taranis I am using both XJT transmitters powered at the same time with the external XJT module set as a DJT module
using telemetry D-series sensors in PPM, Com 2 external telemetry cable.
The Taranis internal XJT, I have to use PXX and so I did try D8R-XP receiver,
but decided to use the X8R receiver as the signal locks to it better then the D receivers.

Re: ERSKY9X on Taranis: (viewtopic.php?f=7&t=4582&start=360#p99734)

I should be ordering the XJT module soon before the new restrictive RC model laws come out this Christmas.

Bob B.

[jhsa]

Bob, there might be a solution without having to mod any RF module.

Mike, what about a "CD4066" or similar? would it do the job connected to the arduino, or any other pin of the 9Xtreme or even the 9x board?
That is the IC the 9x uses to switch the PPM signal, right? Does it have two unused in/out that could be used?

Thanks

João

[MikeB]

As usual, things are not as simple as it may seem. The XJT module sends a logic level signal, but the DJT sends a RS232 signal that switches between +6V and -6V. This negative voltage prevent direct use of a logic multiplexor, or even a mosfet as that has a diode built in.

Mike.

[jhsa]

Reed relay? A couple optocouplers could also do it?
I will do some testing as well. Gotta find my breadboard.
João
EDIT: It won't work with one FET.. what about with 2 in a solid state relay configuration? Hmmmm,the reed relay option starts looking very attractive. Simple...

[Kilrah]

Yep.. that would be the case for having 16 channels with 2 D modules.. I think this is the big reason to be able to use 2 modules at the same time? Even 2 XJT for 32 channels max? I don't use X Gear and don't plan to though..

Yeah, but there isn't really a need to have telemetry on both sets then. Actually none of the open firmwares currently support 2 concurrent telemetry streams as that has never been a need nor been requested. OpenTX has been "prepared" for it when the telemetry system was reworked if the need arises one day but the functionality is not fully implemented.

Two XJT modules "collide" on the SPort, you cannot disable the telemetry from one of them.

You actually can, and that's why the "2 XJT simultaneously" solution is possible on the Taranis, just only the internal one has telemetry.

Again none of these boards have been designed for "anything you could think of regardless of how useful it is in real life, plus whatever anybody might come up with in the next 2 years".

They're made to offer a good set of features in an appropriate packaging at an appropriate price point, with some expansion capabilities that "makes sense".