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Stick-Input interfered by A7105?

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06 Aug 2018 21:02 #70138 by yaKOS
Stick-Input interfered by A7105? was created by yaKOS
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!

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07 Aug 2018 10:21 #70147 by Fernandez
Replied by Fernandez on topic Stick-Input interfered by A7105?
Can you check you Tx bat voltage readout at mainpage, is it also fluctuating?

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07 Aug 2018 11:53 - 07 Aug 2018 12:00 #70148 by yaKOS
Replied by yaKOS on topic Stick-Input interfered by A7105?
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.
Last edit: 07 Aug 2018 12:00 by yaKOS.

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07 Aug 2018 14:48 #70150 by Fernandez
Replied by Fernandez on topic Stick-Input interfered by A7105?
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...………..

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09 Aug 2018 10:59 #70178 by Moeder
Replied by Moeder on topic Stick-Input interfered by A7105?
Did you notice voltage fluctuations in other 7105 protocols as well?
Is you cyrf module using the diode mod?

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09 Aug 2018 12:22 #70180 by Fernandez
Replied by Fernandez on topic Stick-Input interfered by A7105?
It is most present in frsky or flysky but a full power, dsm at full power is less issue.

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10 Aug 2018 12:04 #70198 by yaKOS
Replied by yaKOS on topic Stick-Input interfered by A7105?

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?

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10 Aug 2018 12:28 #70199 by Fernandez
Replied by Fernandez on topic Stick-Input interfered by A7105?
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 !!

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