FrSky DHT module

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JohnH

New member
Jul 27, 2018
1
0
#1
If the attached switch is left in the 2-WAY position (open) can the module still be used with a non-telemetry receiver?
Thanks,
 

Wayne

Administrator
Staff member
Nov 29, 2017
806
90
Novato, CA USA
#2
Yes, I personally would just leave the switch in 2 way mode. (Also known as D mode.) You can still bind to the V8-II non telemetry series of receivers that we sell. Just follow the binding instructions on those receivers, you will use a jumper while binding.
 

Retired

New member
Aug 6, 2018
34
1
#3
New user name and to the forum, not new to many that know me.
To save space in my old time transmitter 2.4g conversions I just unplug the sw. In the center position it’s in the open non connection mode and is in the 2 way mode.
If I need a fw update I can plug it back in or just use a shorting plug/connector.

I stick with D receivers and actually use the telemetry that beeps the dht alarm, to keep track of rssi. Too low and I’ll get beeps.

I haven’t done this lately but from memory,
If you use a D receiver
the rssi can be set to beep at low, critical, and loss of signal via the Frsky usb programmer and the dht data port. I believe it’s preset at 54.
I usually leave it at the factory default and only get an occasional beep. Never loss of link or control.
There’s also a low onboard plane lipo warning I don’t use.
The D receiver needs the resistor Frsky divider sensor. Only issue is setting the alarm for 2 or 3 cell lipo.
Only catch there is you’ll need the sensor and cell setting for any receiver you bind to this dht or it’ll beep/complain.
I’m thinking that the dht dashboard add on can change all this on the fly vs setting it with your computer. This I would use more.

Again all this from memory at the moment but I’m sure Wayne can verify it.
Glen



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Wayne

Administrator
Staff member
Nov 29, 2017
806
90
Novato, CA USA
#4
The RSSI alarms should be set at 45 for low and 43 or 42 for critical. I would not alter these. In fact, altering these may be very hard to do with out the LCD screen that FrSky used to sell. They have been off the market for a couple of years now. I don't think the newer Dashboard will do much with the DHT modules, it is intended for the X modules.
 

Retired

New member
Aug 6, 2018
34
1
#5
Ok on the values.
Never hearing a alarm or going lower occasionally to 49 with 51 typical, I never fully researched the lowest values. Anything above 40 seems to work but I’ll use your actual recommendations if I’m not now.

As for obsolete Frsky products Wayne, I think I have them all.
Dht Dashboard, current meters, volt meters, rpm sensors, altimeters, gps, even a liquid capacitive fuel gauge sensor that used the D hub.
The fuel gauge never really got discussed as to how well it witnessed and didn’t last line as a accessory?


I use X receivers and sport sensors for better installations now and the D 4,6, and (8ch so many versions of them) for my knock around planes.
Never a link issue with any of them btw.

Now what to do with all of the discontinued items is the challenge?
If you have a Frsky museum at your shop I could supply you with plenty of relics. Even the early dht with dip the switches dongle board.
Glen



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Wayne

Administrator
Staff member
Nov 29, 2017
806
90
Novato, CA USA
#6
Maybe donate them to those guys at the AMA Expo that shows off the vintage radios. :)

Yeah, I think packet loss starts to happen in the mid 30's on the RSSI. So still pretty darn safe with the alarms set higher. I have never seen a need to mess with the stock numbers. Some of our customers that fly large gliders will set them to a lower number as they fly out to the edge of their vision a bunch.

Personally if I need more range, I will use the R9 module for vastly improved range. The L9R is a neat option also for a fraction of the expense.

I'm looking forward to your new project. Should be fun. Your box of goodies shipped out earlier.

-Wayne
 

Retired

New member
Aug 6, 2018
34
1
#7
Great!
I better clean off the workbench because it usually arrives fast from Aloft!


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Retired

New member
Aug 6, 2018
34
1
#9
Wayne, check your emails. I sent you some pictures of what I’ve come up with.


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Retired

New member
Aug 6, 2018
34
1
#12
If the attached switch is left in the 2-WAY position (open) can the module still be used with a non-telemetry receiver?
Thanks,
As Wayne posted the center position is where I leave my 3 pos sw ( open circuit position).
In fact I just unplug the sw now and done bother to mount it. A jumper plug could be made in place of the sw, wires to short the center connector pin to either of the outside pins for the other modes if ever used.
So far I haven’t needed to.
That or for a fw update, plug the sw back in.

While working on converting a XJT module into a XHT ( new name ) diy module to offer more options then the DHT, I traced out the sw board circuitry. To my pleasant surprise, the bind/range test button shorts a pin to ground. Wayne suggested that instead of mounting the entire sw/led board to a case to have access, why not just a single hole for a button.
You really don’t have to see the LEDs as the beeper verifies the button mode if pushed.
I’m sure the DHT bind/range test button does the same and shortly I’ll post a traced out schematic. It may I’m guessing, be the same as the xjt button/led board.
In any future DHT installs I’ll only be adding a button on the tx case. Much simpler than mounting the daughter board. Also 3 pos sw unplugged.
Glen



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DEvil0000

New member
Oct 4, 2018
4
0
#13
Hi guys,
I am thinking about flashing the DHT with some other firmware to enable FRskyX instead of V and improve the range by increasing the transmit power.
The only pice of the puzzle I am missing is a schematic of the DHT. I need to know which stm32f1 pins go to which pins/button/led/function...
I am more a software guy so it would be a great help if you have it and could share it.

Thanks
 

Retired

New member
Aug 6, 2018
34
1
#14
Frsky keeps their schematics and design info on a proprietorial need to know basis requiring a non disclosure agreement. Anyone with that level of access can’t share it legally.
However reverse engineering that’s going on by others hasn’t seemed to have caused them trouble.
There are those on the rcg and openrcforums sites that discuss diy upgrades or modifications.
I’m sure someone there can answer your questions.
This GitHub link discusses making your own multi module and offered the fw you can modify as well as flash.
https://github.com/pascallanger/DIY-Multiprotocol-TX-Module/blob/master/README.md

I do use something like that for my few dsm2/x bnf planes but stick with the real dht or djt for my “keeper” planes. As another newer option, I’m going with a xjt or one modified as a XHT, since it gives me more options and trust with my plane control links over the GitHub option.
Some say the Chinese RF decks used are iffy.




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DEvil0000

New member
Oct 4, 2018
4
0
#15
I plan to exactly use this as firmware but since I am more a software guy figuring out the pin assignments is the tricky part for me.
 

DEvil0000

New member
Oct 4, 2018
4
0
#16
Hi,
there are two packages for which I can not figure out what they are. Do you have any idea?
One is labled 26pk with I think 2 sides with each 3 pins.
The other is labled in two lines first line is t212 and second line is h611 with 4 sides with 4 pins each.
Both ICs are close to each other and close to the antenna.

Thanks
 
Aug 6, 2018
34
1
#19
The one with the 6 pins could be a hsms282x series Schottky diode ic used to detect the swr voltage.
I don’t know if the dht/Djt has swr detection, the xjt does.

http://www.redrok.com/Diode_Schottky_HSMS-282x_1pF_100pS_12O_0.34V_-15V_AVAGO.pdf

Maybe the other ic is a se2431 RF front end ic?

Openrcforums has many subscribers with a lot of diy knowledge topics.
Many were involved in the original flysky or HK th9xr transmitter modifications that used the Djt module. Probably why we have the original Frsky x9d Taranis. They paved the way for Frsky.
I’m sure there are those there that know all about the djt’s design.

Check out the discussions.



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