Frequency hopping experiments on the NRF24

[tiptipflyer]

Hi guys,

while watching Phils experiments with the NRF24 radio during the lockdown phase very closely, I wanted to give it a try.
After obtaining all necessary parts I decided to build a single channel version of it. That was before Phil came up with its S/C NRF24 outfit. So I removed everything I did not need from the sketch of the propo version of the transmitter and removed all gimmicks like expo, rates, timer, mixer, propo channels etc. just leaving the single channel stuff and added a sequential throttle on a separate button, like I did on all my dual button S/C transmitters. The only extra is now a throttle led. Since I do some sequential flying also, I will add sequential rudder also to the code.
After some minor problems, all was working well and today was flighttest-time.
Using my old Pageboy, I had several wonderfull flights with the NRF24 S/C system. All was working great, no problems, no glitches, no range problems.

The transmitter uses an Arduino promini and a high power unit. The case of the Futaba FT5D replica is 3D printed, the meter salvaged from an old Futaba tx. The black button on the right is the compound rudder and kick up elevator.
The white left button is the sequential three position throttle.
The receiver is a RF nano wired only for rudder and ESC.
As said before, it is working very well, no issues.
Thanks Phil for a wonderfull project, that keeps us busy.

Cheers
Frank

Edit:
Sequential rudder is now added. If you press the button upon start-up, it switches to sequential rudder.
If you just switch it on. it starts on compound incl. kick-up elevator.
The extra throttle button is very convenient when using sequential mode and allows electric power to be used with ease.
Provisions for rubber ecapements are on channel four.

Frank

[MaxZ]

Looking good Frank! I am doing just the opposite, deleting the S/C functionality, and building a 2/3 channel propo unit
The condensator you are using on the Rx seems a bit smaller (in size) than the one Phil was showing, what is it?
And by the looks of it you are using a brushed motor, any problems with electrical noise? Did you install a low nF C somewhere hidden?

Cheers,
Max.

[tiptipflyer]

Hi Max,
the capacitor in the Rx is a standard 100nF plus a 100µF 10V elko on the other side.
The brushed motor in the Pageboy uses 3 capacitors 47nF each between the terminals and from the terminals to the metal case. No problem with noise.

Cheers
Frank

[Phil_G]

.... all was working well and today was flighttest-time. Using my old Pageboy, I had several wonderful flights with the NRF24 S/C system. All was working great, no problems, no glitches, no range problems.

Fantastic Frank, very well done indeed

Lockdown has some benefits


Max, yes the D9-D13 connections are straight through and you can wire them directly, though I find the adapter connections are neater, especially the folded-over version

I always use the ingrained BT colours, old habits die hard...
blue (D9), orange (D10), green (D11), brown (D12), slate (D13)...
and red & black for power:

I am doing just the opposite, deleting the S/C functionality

Theres no need to delete it Max, just ignore it

[tiptipflyer]

The next transmitter is ready, this time a four channel proportional one.
It is an old, much used robbe Economic set, which I converted using the NRF24 high power unit.
To power the unit I used a small 3.3V step-down converter. This one uses the same 3.3V chip than the much bigger adapter and is a lot easier to fit.
I used Phils propo sketch and removed all extras I do not need, leaving just the basic four channel unit with throttle lock and servo reverse as the only extras.

Flight-test was this morning, no problems. Works fine, no glitches , no range issues, all great.

I also tested the Futaba S/C replica using this time the low power unit.
After the Pageboy was about 50m away and climbing, the trouble started. I managed to come down without any damage, but the low power unit is not suitable for flying.
After reinstalling the high power NRF24, the flight was continued without any problems.

Cheers
Frank

[Wayne_H]

Well done Frank (yet again )

I have to hand it to you - you are a "machine", and an inspiration, when it comes to turning out these projects. Keep it up mate!!!

[MaxZ]

Congratulations with another successful project Frank!

I am still working on mine, but I am waiting for the missing parts which seem to be lost in the sky between China and The Netherlands

Mine will be a 2-channel version, but all the electronics and code are there to expand it to a full 4-channel propo Tx, all I will need to do is install a second stick unit and a third rate pot (and stuff it in a larger box..).

Where did you get the nice little 3v3 converter? It would make sharing a Nano, an NRF unit and a converter in the compartment ahead of the stick unit a bit easier......

Cheers,
Max.

[tiptipflyer]

Thanks guys.
The 3.3V step down converter are available all over the place, here is one example:
https://www.ebay.de/itm/2-5-10PCS-AMS11 ... SwQZFd~dBa
If you buy 10, they cost less then €0,34 each.

Frank

[Phil_G]

Fantastic Frank, very satisfying isnt it?
50m with the low power module is pretty good I thought!
Thank you for your encouragement with the project, and for the regulator idea, I do have some but it didnt occur to me to use them with the transmit module! Its a great idea as the 0v and 3v3 pins align, so the regulator can sit rigidly on two header pins. I must remember to solder the NRF wires first though, they're harder to get to once the reg is in place.

My last batch of regs arrived as a 'biscuit' - quite impressed that they stayed that way through the post!
As you can see they're a quarter of the size of the standard regulator:

This seems to be a really stable, repeatable project, I've made loads of them now and they all just work straight away. I just made another S/C emulation setup using a 'Strong' and Franks regulator idea, which makes a really neat job:

I made the NRF connections exactly as the diagrams in previous posts with a 'sideways' servo plug:

...the only untidy bit was tagging on the neg wire to the NRF corner terminal, which is one of the two standoff pins for the regulator:

A few have queried the speed of the link & re-link which I emphasised in the last video

Whilst Frsky is much quicker than Spektrum, it still takes a second or so to re-link. The reason the homebrew NRF is instant is that here is no handshake, GUIDs are already stored and hopping schemes are already known, theres no memory-match exchange, etc... This is one of the reasons I'm not tempted to add a bind handshake sequence, I like having it hard-coded, I like the fact that I can have two transmitters with the same configuration and switch transmitters in mid-flight without even the slightest latency
Even an overlap doesnt bother it - whilst both are 'on' the receiver will choose one tx or the other, until either tx is switched off, nothing catches fire, the sky doesnt fall, theres no magic smoke...

[iflylilplanes]

Hey Phil, How much for a TX and RX without batteries and servos to Australia? just wondering, should fit inside an OS Pixie case with room to spare.

Cheers,

Dave