868/915 Mhz as a viable frequency for submarines.

Yes,  and the r9m and r900 would bind, and i would get telemetry, but when actually moving servos, they were very jerky, and telemetry would constantly drop out...  "telemetry lost", "telemetry recovered" every 15 seconds or so.   this was with three differen r9m that were original and 2019 models, and a 2019 access version would not even bind (which was expected access != accst v1).

that plus "dozens" of other reasons are why i moved to expressLRS

I will do some more testing soon to see how it performs.

Fingers crossed that your DIY module is better than the FrSky modules...

I have had it running on the bench or over an hour automatically moving a servo back and forward. its been flawless, no telemetry lost or servo glitches or anything like that. I have Done a range test and it went as far as a pair of r9 modules at the same power level. so far i cant find anything wrong with this setup. The only downside compared to a r9 module is the lack of power control, its always 500mw but other than that its all good.

YAY!!! I am happy that you are having good luck with the jumper receivers.


I have spent the day (a holiday here in the states) getting my latest toy working.

An FrSky Tandem XE has somehow found its way into my possesion, and i spent the day trying out different things with it.  I have got the internal 2.4ghz rf deck working with the one access receiver i have, as well as the internal 900mhz rf deck working with the two 900mhz access receivers i have, and that all went better than anticipated.

I felt so lucky i went ahead and updated the following:

a r9m OG (original) accst module
a r9m 2019 accst module
a r9m 2019 access module
a r9m lite module (I honestly don't know if this was orginally accst or access when i bought it, but it is access now)

all to their latest fcc firmware

as well as
3 r9 OG (original) accst receivers (8 channel pwm full size receivers)
1 r9 mini accst receiver

none of the accst 900 mhz equipment will now bind.  the OG r9 mini and one of the r9 used to bind to the OG r9m.

i also tested the 2 r900 jumper receivers that acted poorly before, and they still act just as poorly as they did.

however, the r9m access and r9m lite access transmitter modules will now bind with the two r9 mm ota receivers that i bought just to play with the access protocol...

so i have 3 different r9 access transmitters that will bind with the 2 r9 access receivers that i own.  I did not have to update the firmware on those receivers.   I am wondering if i should push my luck and pick up a couple more r9 access receivers.


in better news, all the expresslrs and tbs crossfire modules i have will bind with all the expresslrs and tbs crossfire receivers that i have    


I have a tbs crossfire micro module, as well as a nano module.
I have 3 tbs crossfire receivers, a nano diversity 8 channel and two nano 6 channel.

I have 4 expresslrs nano modules and 4 expresslrs JR modules
I have over a dozen different expresslrs receivers, with differing crsf to pwm adapters, as well as two wing flight controllers.

I am using 3 different FrSky transmitters, and 3 different Radiomaster transmitters with those different modules for testing.


At some point in time i have promised to do different write ups on all these different devices.

At some point in

Im sure I was using the accst flex firmware when I first tested an r9 module with the r900 receiver a while ago. As far as I know, there is no physical difference between the accst and access r9 modules apart from some minor tweaks to the voltage regulator so should work with any firmware.

can you tell me exactly what firmware files you used on your module and receivers? frsky is a bit of a nightmare with all its versions of firmware and most are incompatible. with so many things not working correctly I think there must be a common issue as everything I have tested just worked once the right firmware was on it.

I think the issue is your using the FCC firmware and not the flex firmware, both LBT and FCC firmwares are restricted and cause compatibility problems.

flash all the modules with the same accst flex firmware. the modules are all physically the same. I use both modules with the same 3rd party firmware.

As far as i know there is no real benifit to access, frsky just made it to stop the Chinese clone receivers working with their new stuff.

I think I just came across aR900 recevier bug, I went to rebind it and as far as the leds were showing, it was connected and I was getting telemetry. but I was getting nothing out the servo pins, eventually I bound it again and all is well.

So,

here are the results so far.


the r9m 2019 accst rf module has been flashed to the latest FLEX firmware, and one of the r9 receivers.

those two now bind, but act like the jumper r900 receiver. sporadic servo control, constant "telemetry lost", "telemetry recovered"

the jumper r900 receiver now acts SLIGHTLY better. the green light is basically flashing constantly, and the "telemetry lost', "telemetry recovered" messages are appearing almost constantly... and the servos are moving almost in real time.

Im not sure how the jumper radios are wired but i know on taranis radios if the internal module is still enabled even if its not connected you will get issues like your describing.

make sure the internal module is disabled.
try setting the radio to ppm out rather than r9 mode to see if it improves servo movement.
can you try the r9 module on an frsky radio? does it do the same?.

100% of the testing has been done using a FrSky qx7

Internal rf deck turned off

r9m fcc mode for external module. tried both the OG r9m and the 2019 r9m using accst flex firmware on both of the modules and a r9 receiver.

i do have a radiomaster tx12 mk2, and an original FrSky x9d that i suppose i could try as well...

the r9m access modules were tested on the following:

r9m lite access module:
2 different Radiomaster Zorro transmitters
FrSky Tandem XE.  

r9m access module:
FrSky qx7

the two r9 mm ota receivers registered and bound with all the access modules on all transmitters attempted.

so basically, 100% of the r9 access receivers i own work with 100% of the r9m access modules.

Strange so it's just the accct module that's being problematic? All the other radios worth with the access modules ? That is very strange. The only other thing I can suggest is flash the accct module to access to see if it starts behaving and rule out it's some kind if hardware issue.

there are actually 5 r9m modules being discussed here

OG accst (black case, no external battery connector)

2019 accst (orange case, yellow xt30 external battery connector)

2019 access (orange case, yellow xt30 external battery connector "access" protocol marking)

brand new r9m lite access module.

brand new tandem XE with internal xjt access 2.4ghz module as well as an internal r9m access module.


the two accst models have been updated to the latest flex accst firmware, as well as 3 r9 receivers and they will bind, but have sporadic functionality with every single accst receiver, 3 r9 receivers, 2 jumper r900 receivers and a r9 mini receiver.

prior to this latest round of upgrades the OG r9m module would bind with one of the r9 recievers, and the r9 mini. all three of those devices were purchased at the same time, when FrSky first released the r9 system. all of the other accst receivers and modules were purchased at different times over the last 5 years, and none of them would bind with anything else. basically buying different items from different distributors to try to find things that would work.


the r9m 2019 access module was purchased used with the qx7 about a year ago to try and see if the r9 access world was any better than the horrid luck i had with the accst world.

i just now got around to the access testing because i have been having such good luck with the crossfire and expresslrs, i felt i didn't want to waste time chasing an impossible task with the r9 equipment.

the r9m lite module was purchased 6 months ago when i picked up a radiomaster zorro. it requires the lite style module, and uses edgeTX... that presented a different set of variables to test.

buying the tandem XE with the internal r9 access module made me begin the r9 investigation again. hoping i could run my submarines without an external module.


all in all the existing failure of the r9 accst mimicks most of my past experience with r9 equipment. i was actually suprised that the access testing went so well.

have you tried updating one of the older modules to access to see if its a hardware or software issue?

I was updating my R9m modules with the latest Mlrs firmware when I found one that I had not flashed yet so I have updated it to the latest Accst flex firmware and I can replicate the issues you are describing with the R900 receiver. delayed movement, random servo movements, its really strange. I will investigate more.


tested, FCC, EU and flex mode. all the power levels. PPM mode, no change,

tested much older firmware R9M_FCC180329 this wouldnt even bind to it.

So it may be that we need to find an older version of the firmware?

tsenecal wrote:So it may be that we need to find an older version of the firmware?

the older firmware i found wouldnt even bind to the r900.

Its possible that its incompatible due to the changes frsky have made. The R900 is designed to work with the 5 in 1 module in the jumper t18 radio so its not surprising I dont have any issues using it with my DIY 5 in 1 module. from what i could find searching I cant find any mention of anyone using the R900 with the frsky module successfully. I found one person say that it was not compatible. other than I couldnt find any solutions other than to use a 5 in 1..

Bottom line is I think the R900 uses most of the frsky r9 protocol but there is enough subtle differences that it its not fully compatible.


some people are reporting it working and some are saying its not working.  I cant find any commonality.

https://www.youtube.com/watch?v=ftLlJbSOx3I


Some progress!
binding in EU mode with no telemetry has eliminated all the servo glitching problems. so i think there is probably some kind of timing issue where the radio and receiver are not staying in sync.

that is very interesting.

what are you doing to the r900 to support eu mode?  i am under the impression that eu vs fcc is firmware (either using flex firmware or eu firmware to get eu mode)  are you updating firmware in the r900?, if so, how?



as to testing eu/flex firmware in both an FrSky r9m and an FrSky r9 receiver...


I have already updated to the Flex firmware, and that was the version that worked better on r900 than r9...


One of the Comments on the youtube video link specifically states to bind with NO telemetry.
One of the Comments on the youtube video link specifically states to use FLEX firmware on the r9m.

I will test both of those setups.


I did want to add...   i have almost a dozen of the jumper r8 2.4ghz receivers.  I love them, they are fantastic inexpensive replacements for the FrSky x8r receivers.   that is why i bought the r900 receivers, hoping they would be as rock solid as the r8 are.

If your using opentx I think there is an option when you build the opentx firmware in companion for the r9 flex mode, I think you need to set it to get all the separate modes and power levels.

The r900 will bind in any mode surprisingly.  FCC,EU,868,915 for some reason the no telemetry option only shows up under EU mode on my radio.


my understanding is the main difference to the EU firmware is the LBT so it checks if something is on the channel before transmitting, if something is there it skips it.....sounds good till something is jamming the airwaves and your transmitter essentially goes offline.

I know that when i bind accst d16 fcc i can pick 8 or 16 channels, telemetry or no telemetry, i will try that with 8 channels no telemetry first.

then i will update the qx7 firmware for flex support, then update r9m with flex firmware and try the 8 channel no telemtry test with both fcc and eu settings.

deleted.

So, when i finally got home tonight, i just went ahead and updated the opentx on the qx7 to support flex, then updated the r9m 2019 and all the frsky r9 accst receivers to flex.

i select r9m 915mhz as the protocol for the external module (i had 2 r9m choices before, i have 4 now)

everything now binds. all 5 receivers

I have to use 8 channel no telemetry for the jumper r900s

the frsky r9 receivers will bind with or without telemetry

the r900s still have green flickering LEDs, but they are flickering so fast now that they seem to have continous capability...  all the r9 and r900 receivers have fluid servo movement, no chattering, no drop outs of functionality, no "telemetry lost", "telemetry recovered"...  until i actually turn the receiver off.



Thanks Geofrancis for all your help above and beyond the call of duty on this.

good to hear!
Years ago I used to work at a place that sold all the frsky radios. I was probably one of the first people in europe to get to use a r9 system, but I never owned any r9 stuff myself, as I used openLRS. It wasn't until recently that I started using it for Mavlink telemetry using a custom firmware. for long range telemetry I use a r9m module as a receiver, that way the telemetry will go as far as the RC. that's why I have 6 R9m modules lol your just lucky I happened to have one that had not been flashed yet as the other one I had bought already had expressLRS on it.

Sadly, the problems that you and i have had getting all these receivers to work has not helped my opinion of FrSky's work in the 900mhz area vs others like ExpressLRS (still my favorite) and TBS.


But it is nice to know that I know have an entire suite of 4 different protocols in the 900mhz frequency range to test and post my results on.