V202 protocol

Yes...it's on eof those Saleae clone I think. Got it from Banggood.

I have been following all this pretty closely. And it was never mentioned that it was a RX and TX combo. At one time, they sent RX. Then finally...BG came out and declare it was the TX and shipped replacement to everyone who contacts them. So I thought they finally traced it down to the TX being the culprit. (I had my doubts)

Anyways, the v262 is brand new. Came in on Friday. It's the newest bird so I thought it had the latest RX code. Yet, it still suffers from the DO issue.

Like you said...nobody but WLToys knows. (But I wonder if they even know how to fix it.)

We talk to JamesChen via IM and he doesn't have any more info than what's out there publicly already.

Yea, then it's kind of sucks. They use very cheap components in TX, and not much more expensive in RX. This limits processing power they can afford for protocol correction tasks, and well designed radio is magic by itself (apparently, not present here . It works for me, which probably means they have unfortunate batch. Also, they use nRF24L01 clone the quality of which defines performance of radio.

Also, I learned about both TX and RX being fixed from this post www.rcgroups.com/forums/showpost.php?p=25592618&postcount=9 , I'm not sure how precisely it describes the situation, but judging by JamesChen's answer, it seems so.

Summarizing the facts

All TX have DO issues:

1) old stock TX
2) new stock TX
3) devo 7e

potential RF signal quality related DO sources

1) good luck TX and RX are both of good quality (seem to exist, indeed).
2) Rx is bad (quality of components), replace of RX sufficient to sove DO issue
3) Tx is bad (quality of components), replace of TX is sufficient to solve DO issue
4) both TX and RX are bad quality and need to be replaced

Transmission routines related DO sources:

1) new TX is sufficient to sort out the DO issue due to some changes in the transmission routines which do not require protocol change

Here, Victor reported that he does not have any DO issues on Devo 7e.

victzh wrote: ...My code which does not produce such irregularities works perfectly for me - no dropouts on V202 and V212 so far.

It seems that it can be excluded that the DO issue is protocol or transmission-routines related, unless Victor's code is not the same as in the deviation nightly builds repo:)

It's than more to the quality of the RX-TX. Once I received my replacement TX, I will report here.

I read today again that somebody else has his DO issues solved by receiving the new TX

martybabe wrote:
I don't know if anyone's mentioned this yet but I received the 'free' replacement transmitter for the V222 from Banggood this week.

The dropout issue is completely resolved and I am finally able to put the V222 through it's paces and compare it to the 959. Simply much better in every way except for the flip button which seems a bit hit and miss.

I cant believe I've had to wait so long to actually fly it but does fly really well, even inside my small house, I even managed to fight a fairly strong wind with it today. It seems more responsive and easier to control the 959, so all in all I'm a pretty happy bunny.

technofuzzy wrote:
Yesterday I received my replacement TX from Banggood, did some flights without dropouts.

However, following my logic, the new TX may not solve the DO issue because the RF components in my Devo are different and of good quality with original nordic nRF24 chip (tested on another project of mine).

Therefore, my last resort will be to ask BG to send me a new FCB. If it does not work with RX-TX pair completely exchanged, than I am really stuffed.

Just a different question, can that be that devo 7e running deviation has its own issues with controlling the nRF24L?

I have the impression that the DO-less range on the stock TX is larger than the DO-less range with Devo 7e equipped with 19 dB PA nRF24 module.

For instance, I've never had a single dropout when flying indoors with the stock TX, whereas yesterday, I had a plenty of DOs when flying in my living at the distance of 4-5 meters with modded devo 7e.

I noticed that deviation has a power setting in the model.ini file. I set it to 100mW. But I don't know if it is really set as a dB value in nRF24 chip (RF_PWR register) or whatever reaction of the deviation to this setting is. Victor, can you advise please? You could know it...

victzh wrote: Original TX was pretty sloppy in the timing and extra, non-nonsensical packets. If they fixed it, it should improve. There is no way to change the protocol only on TX side, so the protocol is basically the same. What they could change is packet repetition rate (if you triple the packet instead of doubling it as it is done now, it probably can enhance reliability), remove garbage packets, strictly observe frequency change pattern (first TXs had unexplained temporary change in this pattern which could easily be responsible for dropouts).

Logic analyzer is what helped to reverse the protocol in the first place. If I could get new TX (probably some of the distributors can be generous enough to provide it, I'll try to contact MassiveOverkill who helped me once before) I'd definitely re-analyze the new implementation - scripts are still there. It would be also interesting to look at genuine V222 TX.

Also, you should not discount RX as a cause of dropouts - antenna can be folded - it should not - or inappropriately soldered. Also, antenna length matters somewhat, makes sense to check that it's close to 31mm.

Consider it done bud

I'm sending you an updated TX board pictured in this thread:

www.rcgroups.com/forums/showthread.php?t=1969101

@MassiveOverkill Thanks!

@MassiveOverkill, BTW my address changed. I will send you RCGroups PM.

Just received and tested the new TX. First of all, it didn't work, only red LEDs light was lit when powering the unit. No LCD display or buttons where working.

Opened the tx and immediately saw a badly soldered place on the PCB. Soldered it properly and it works now. The overall quality of the Tx' PCB is not good.

What else: the DOs are still there, no improvements at all. As far as I am concerned, it was an alibi action by BG to replace the unit.

I will ask BG for refund and send the quad back to them.

Today, I made an extensive range test with all three transmitters: the old, the replacement TX and the Devo 7e. I was in a park with very little RF-pollution.

The old TX performs the best. You can fly it safely in 10-15 range, then it falls.

The new TX and Devo 7e with 79mw PA and ceramic antenna (decibit module) perform the same. The quad reproducibly does not make it even to 2-3m distance.

I did 3 videos for BG Customer Service. If anybody interested, I can provide the youtube links.

I can not understand what the problem with Devo is. I checked the deviation source code for nRF24 chip init and looks like with my config it writes a 0x11 into RF_SETUP register (for 0 dB max power). Next days, I will compile the deviation source code and make sure that this value is indeed active in the chip by uncommenting the code line and leaving the the default value after reset (the default is the 0x11).

It could be that the max power value is not properly written for some reason.

Uh-oh, I just took a look at the decibit module you use. I am not saying that it is the only reason of bad performance, apparently RX configuration matters a lot, but the module uses ceramic antenna, which seems to be oriented horizontally. For the best performance the receive and transmitter antennas should be collinear, in practice it means they both vertical. If the antennas are perpendicular the reception strength is theoretically zero. I am afraid, that's your case. I used another module, and in another Devo - 10, not 7E.

One extra thought: the specs for you module list required current as 120mA, make sure Devo 7E can provide such current. On the other hand, people use modified original CYRF6936 transmitter with PA with great success, so probably it can feed the module.

Privet,

Victor, you may be right regarding the ceramic antenna. It is never good to use different antennae on an RX-TX pair (ceramic and dipole). I used these decibit modules as an RX-TX pair which performed well through a couple of walls. I will have to check if your idea is right. I have another nRF module without PA (10 mW) and a PCB antenna. As a last resort, I could try to transplant the transmitter from the old TX which had the best range.

However, what I also don't understand, why there is such a big difference in range between the new and old TX from BG? They should use the same modules. Or is the quality range of the transmitters so wide (good->worse->even worse->worst)?

Regards,

The RF part is very capricious, so to tune it well requires some effort. The antenna length, its match to RF chip etc. etc. matter in this respect. I've seen reports by people tuning up stock TX and RX to the point when there are no more drop outs. It takes special equipment to achieve, so it's beyond abilities of a regular user. You probably have an extra unfortunate piece of RX, that is why your range is so short disregarding what TX you use. So, yes, it's basically a problem of unfortunate design + weak QA.

hanryz wrote: I will have to check if your idea is right. I have another nRF module without PA (10 mW) and a PCB antenna. As a last resort, I could try to transplant the transmitter from the old TX which had the best range.

You can test with the tx turned by 90 degrees.

Hi, the power distribution profiles (antenna patterns) and (maybe) polarizations a of a ceramic antenna (on my devo) and dipole (used on the quad) don't match, clear.

Nevertheless, if you think of wifi routers, they often have kind of ceramic antenna in them, however, it seems to work well with many different antennae of client devices.

So, turning the TX by 90 degrees may lead to an increase of range, but this will not be huge.

What is imho more important is RF power and sensitivity. Of course as long as you don't make some bad mistakes with the antennae.

In my case, I simply don't believe that the maximum range 2-3m at 19dB power and 90dbm sensitivity comes from the ceramic antenna only. There must be something else out there.

What else could be wrong:

1) RX FCB has design/QA problems. In this case, it does not necessarily explain why the other new TX I received from BG performs much worse than the original TX, unless there is also a QA problem with the transceiver chip in the new TX.

2) Something wrong with my nRF PA module (will need to check)

3) deViationTx problems of the build I use.

4) A Combination of the three previous sources.

I always wanted to have a spectrum analyzer. Now I have a reason to buy one:). I consider to order the RF Explorer to analyze the spectrum of all my TXs. This could shed a bit more light on what's wrong.

hanryz wrote: ...Nevertheless, if you think of wifi routers, they often have kind of ceramic antenna in them, however, it seems to work well with many different antennae of client devices.

WLAN routers often have more than one antenna, mostly orientated 90° to each other to avoid dark holes.

So, turning the TX by 90 degrees may lead to an increase of range, but this will not be huge.

Look at this: http://static.rcgroups.net/forums/attachments/1/0/3/1/1/3/a3795947-178-1240Cloverleaf%20no%20ground03.jpg . This is a typical antenna characteristic for a dipole antenna (in this example it is vertical oriented). It puts the most energy in a direction 90° to the antenna in form of a torus. If you point to the model, the loss will be obviously huge...

...I always wanted to have a spectrum analyzer. Now I have a reason to buy one:). I consider to order the RF Explorer to analyze the spectrum of all my TXs. This could shed a bit more light on what's wrong.

There have been some folks here who used spectrum analyzers but I don_t remember where the threads are... search for. Maybe it is already done and you will get a reference to start with.

I would not worry about the shadows as they call the dead spot. There are several factors in play as antenna use and TX power. Say you use the nRF24L01+PA with 18dbm power you and the heli is exactly in the dead spot, the heli reception distance will be reduce not totally drop unless you are talking about the heli being 700ft away from your transmitter. Don't know about you but my eyes can't see the small heli that far away.

hanryz wrote: In my case, I simply don't believe that the maximum range 2-3m at 19dB power and 90dbm sensitivity comes from the ceramic antenna only. There must be something else out there.

Can you be a bit more specific about your setup - what TX module and RX board are you talking about?

V202 early helis are known for bad RF design and dreadful QC, but as far as I can recall it was more about TX - newer TX boards with BODA (Boosted Omni-Directional Antenna) work well.

I dont actually know how protocols work but I made some experiences. First with DEVO 7e modified with nrf24l01 it drops all the time. With new transmitter is do not drops till the thirh or second cell.I looked and see that receiver card heated. Meybe card heat end stops sending power. I thought if we bybass supply of voltage to receiver we can maybe find solution by the way