V202 protocol

Hi Daryoon,

Could Hisky tx(or HT8 module) bind to V202?
Did you try it?
Thanks.

It was confirmed in another thread and forum that the v202 does not bind to the HT8. But at least with Vitcz' code, Deviation will be able to with the right transceiver installed.

So is the NRF24L01 module like the following the correct one to use with the v202?

www.ebay.com/itm/NRF24L01-2-4GHz-RF-Wire...&hash=item2a2ad71f71

Oh, no external antenna... I would expect range problems. There are modules offered for 500m range which have enough power for flying helis.

There is also this one which does have an external antenna.

www.ebay.com/itm/NRF24L01-PA-LNA-SMA-Ant...&hash=item485448cd1d

Daryoon wrote: It was confirmed in another thread and forum that the v202 does not bind to the HT8. But at least with Vitcz' code, Deviation will be able to with the right transceiver installed.

That's a bad news for me,because I have a HT8.
Thanks, anyway ~~

EDITED! Points to correct nRF24L01 module, thanks to rbe2012.

kingiggy wrote: There is also this one which does have an external antenna.

www.ebay.com/itm/NRF24L01-PA-LNA-SMA-Ant...&hash=item485448cd1d

This one is better, it has power amplifier (PA) which makes it powerful enough to reach more than 15-20m. On the other hand, this one has very bulky antenna connector. Mine had inline connector and I desoldered it anyway and soldered antenna from original V202 module. There is not much space inside of Devo, so I doubt that I will be able to find a place for the third add-on module when I need one. So this bulky connector must go. I used the following module, it is probably no better than yours.
www.ebay.com/itm/nRF24L01-PA-LNA-wireles...&hash=item460a368434

Be careful - the two modules above use different rf chips (nrf24L01 and cc2500) - the headlines are sometimes misleading because they want you to find their goods with any search...
In the description there is written which chip is used. They can't be exchanged.
For V202 you will need a nrf24L01-module.

Oh, shacks! Thanks for correcting it - my mistake. There are two visibly very close modules, one on nRF24L01 and another on CC2500, and I definitely meant nRF, while accidentally referring to the wrong one. I will edit my post to point to correct one.

Submitted pull request for the first implementation.

I implemented it as 6 channel protocol, though actually it is 4 channels + flags for LED and auto flip. So flags are formed dynamically from 2 extra channels.

Auto flip is slightly mysterious, it is apparently not only flag, but some movement of controls which native radio probably implements. So now it works, but only in some cases. Apparently, I need to spend a bit more time with logic analyzer. And may be flying it outdoors to figure out the exact flipping behavior.

So, who's next?

Yes, it is. I connected 8-pin 0.1" connector and soldered CE to VCC right on the connector, so I am not sure what happens if I switch it to CC2500 module. But as V202 does not require manipulation with CE that works for it.

The drawback is you need to pick 2 out of 3 possible addons, so I am thinking of either implementing a board with multiplexors, or exploring some universal radio possibilities with direct mode (A7105 has it, but data rate is lacking, and there are more "standard" radio chips with similar abilities, e.g. ADF7242).

2 put of 3 module isn't too bad. It's already so far ahead of the commercial available radio, I don't mind this limitation at all.

Can't wait to try a nightly with this code. Now to go purchase the appropriate transceiver.

There has been much discussion about a universal module or decoders that allow 3 or 4 modules to be installed.

I plan to have the three additional modules installed (some are still on the way), however I decided it will be much easier to add a small slide switch in the Devo8s battery compartment that switches the chip enable line between the CC2500 and nRF24L01 modules.

This way I have my 3 most use modes available on the GUI and for the 4th, I just need to flip the switch in the battery compartment to enable the nRF. This I believe is a cheap, fail safe and 100% reliable way, with no RF issues or design risk.

PhracturedBlue wrote: The downside of the ADF7242 is that the only pre-assembled boards I can find are the official eval boards which run $100 each. While that is fine for development, it woulkd require designing, manufacturing, and selling a custom board for Deviation. Finding a transceiver with a pre-assembled board that could be used at reasonable cost would make the overall project more appealing. But I'm flexible. If you have the knowledge to lead the way, just tell me how I can help

Yea, I understand the drawbacks of not having a ready made, PA equipped module. But first, ADF7242 has PA inside, it's not that powerful as stand-alone, but anyway, it's 4.8dBm which is better than standard 0dBm. Actually, impedance match and power output is the only physical problem, though it can be solved by tedious soldering of 0402 components and measuring output, or at least, transmitter range. I turned my attention to this particular module because Michael Ossmann of Ubertooth fame planned to use this instead of CC2400.

On the other hand, there is such beast as A7125, which unfortunately does not exist with PA, but it has right bit rate, direct mode (with code examples) etc. May be if we ask politely on Aliexpress, they already have it with PA, or can order it.

The filters is another issue, as you mentioned. I did not dig it deep enough, I've seen that spectral data is specified for CC2500, but don't know about others. Also, modulation can be GFSK or FSK, but what matters is the frequency deviation. Again, I remember I've seen this specified for CC2500 (and it's adjustable), should check others.

I am trying to make a table for different chip abilities and corresponding protocol usage to figure out common ground (if any).

A7125 bitrates - formally it is 1 and 2Mbps only, but the register format suggests that less than that is available also - we need to try it. I plan to check FlySky on it, it is very close to A7105 in other aspects.

And yes, I realize that we can't get rid of CYRF6936, nothing else supports very specific DSSS schema they use. By everything GFSK/FSK seems to be achievable.

Ok I received the nRF24L01 module from ebay. Is there any documentation on how to wire this up and test the v202 protocol with Deviation?