Stick-Input interfered by A7105?

Hi!

I just got my first Devo, it's a 7e.
I have installed a A7105-module (shielded with PA, piece of wire as stock-antenna),I bought from china.

It works, I could bind a WLtoys V911-receiver-PCB with no problems, using FlySky-protocol.

But: When I start the chanel-monitor, some chanels are toggling. (+/- 0-3)
I can control the servos and the motor - so transmission works, but the servos are shivering.
(more like a humming sound than a actual movement)

I thaught I've messed up my new transmitter by ESD or by soldering it too hot.
But when I load another model that is using the CYRF6936-module, the Stick-Input is just fine.
So I guess I did not damage the analog-ports of the microcontroller, nor the poti-connections.

I did a Stick-calibration once again, and it works a little better now, but still not as stable as when CYRF6939 is active instead of A7105.
Then I reduced the output from 150mW to 100mW.
Now it's only +/-1 toggling on only one channel now, no matter how many mW.

Could my data-wires be too long and interfere with analog-inputs, or what else could cause this problem?
I have used very thin ribbon-cable, but if that was a problem, transmission wouldn't work I guess.
Could the signal of the transmitter itself interfer the analog-readings?


Thanks for any advise!

Can you check you Tx bat voltage readout at mainpage, is it also fluctuating?

Thanks for the hint,
bat voltage is changing as well:

When I load a model-file using DSM2:
5.60 - 5.64 V ( +/- 0.01 V slowly fluctuating every few seconds)

When I load a model using FlySky:

5.40 - 5.61 V fluctuating about each second more or less:
sometimes it jumps +/- 0.02 V , sometimes 0.09 V

The Batteries used are 4 x 1.5V alkaline AA.
The module used is named XL7105-D03.

I have the behaviour as well and tried a lot, but still can't put finger on the cause of it....

-Changed internal 3v3 regulator and psu circuit
-Added capacitors
-Checked the CPU Vin adc, added capacitor.
-Tried with tx switched on move the antenna around the pcb, see if RFI may increase/decrease the affect.

I do not understand were the fluctuation comes from, I like to get rid of it too...………..

Did you notice voltage fluctuations in other 7105 protocols as well?
Is you cyrf module using the diode mod?

It is most present in frsky or flysky but a full power, dsm at full power is less issue.

Moeder wrote: Did you notice voltage fluctuations in other 7105 protocols as well?
Is you cyrf module using the diode mod?

In my case I noticed, that it won't happen before binding.
(I can only bind a v911 since I have got no other 7105-receiver)

My cyrf-module's diode is untouched yet and I don't have any 2401 or 2500 installed.

I'm gonna try to supply the voltage for the A7105-module from an extrernal source and a common ground and see what will happen.
If it will still fluctuate, I can imagine it's the SPI-wires I am using, so I would decrease their length and/or increase their diameter.

Is it really only Fernandez and me having this problem?

I expect you solve it by supplying the module by external separate psu, let us know how it goes.

It has something to do with current consumption from cc2500/A7105 when putting into low transmission power or range check problem also almost non persistent. Maybe the board design of devo 7e?

In my 7e I removed the small stock 3v3 regulator and use a polulo step up step down 3v3 regulator to power the Tx. The battery I use 2pcs 18650 in parallel, yes it fits perfect with very small modification to tx. (it is reversible mod, so you could still go back to fit original battery tray). I charge the 2x parallel 18650 cells with tp4056, charge and protection module.
The 5v input for the TP4056, I connect to the USB port of my devo.

So I charge devo via USB port now.


But still this fluctuation issue, still there...…..(Same as was originally power system)
But battery last forever !!