Too many packets lost error

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tobias
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Re: Too many packets lost error

Post by tobias » Wed Jul 31, 2013 8:59 am

I'm at a loss, any hints?
It seems like a difficult problem which probably requires expensive RF tools to find. Best option is to contact Seeedstudio support to let them fix it or replace the unit. It might take a while so it is often worth to try to find it yourself first, but in your case it really seems like a problem with the nRF24L01+ chip or the RF filter components.



cvh
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Re: Too many packets lost error

Post by cvh » Wed Jul 31, 2013 4:51 pm

Yesterday I looked into the schematics of the crazyflie together with a friend of mine, who also has a very technical background. Together we figured out how the rf part is printed on the pcb.

This is how my crazyflie looks like: http://mykos.be/crazyflie/crazyflie-top.jpg
http://mykos.be/crazyflie/crazyflie-ant ... points.jpg
Now, the question I would like confirmation on: Is it correct that the parts indicated on the second picture should be connected?

They all turn out to be connected after testing with an ohm meter.

So I guess I have to give fsedano some credit.
I don't have a microscope, but I made some high quality pictures, I can't find any visual defects.
I don't have a ceramic antenna to replace it with. How could I hack a cheap ass antenna as a replacement? :)

tobias
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Re: Too many packets lost error

Post by tobias » Thu Aug 01, 2013 8:55 am

The soldering from what I can see looks fine and so does the connections.

Is there any difference in the radio distance if you power the motors or not? If so, it could be a "small" short between one of the motor connector pads which causes RF interferences due to increased voltage ripple. Measure the resistance between the motor connectors with the battery unplugged. It should measure about 2 ohm.

Another thing you can try is replacing the the blue chip antenna with a quarter-wave antenna. Take a piece of wire and cut it to 3.1cm length and solder it to the chip antenna pad closest to the RF components.

cvh
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Re: Too many packets lost error

Post by cvh » Thu Aug 01, 2013 4:51 pm

Ok, I already did that test, all motor connections seem good, all contacts have about 2ohms between them. Is there any test I can do to check the antenna itself?

So I guess I'll try and have a go with a home made antenna. Any idea on the thickness of the cable? Can the isolation stay on, or do I have to remove it? Can it be a "multiple wired" cable or does it have to be a solid cable?
(I only build a small yagi antenna about 12 years ago with a solid cable 2mm square, it provided my internet connection over a distance of about 120 meters for about 4 years. I remember I had to strip the isolation from the cable parts. That's the only antenna I ever made...so no expertise there.)

Maybe I should also check if can order the antenna in my local electronics shop, do you have the exact component description?

tobias
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Re: Too many packets lost error

Post by tobias » Fri Aug 02, 2013 10:02 am

I'm no antenna expert either but for the test a simple ~3.1cm multistranded wire with isolation should do just fine. If that doesn't help contacting Seeedstudio support would be the next step as it really looks like a hardware defect.

cvh
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Re: Too many packets lost error

Post by cvh » Fri Aug 02, 2013 7:30 pm

Ok, cool! 8-)
I seem to have much better results with a 31mm long wire soldered to the antenna contact after removing the antenna.
I couldn't brake the connection within the room, wherever I put the crazy it maintained the connection!

Just got my first real fight with the crazyflie :D

Thank you very much for helping me out!

tobias
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Re: Too many packets lost error

Post by tobias » Mon Aug 05, 2013 8:20 am

That is good news!

I still think there is a radio HW problem so if you want that fixed make sure to contact Seeedstudio.

absoloodle37
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Re: Too many packets lost error

Post by absoloodle37 » Thu Aug 08, 2013 4:04 am

Could you post a pic of your new antenna setup? I'm considering modding the stock ceramic antenna w/ a RHCP clover leaf or skew planar wheel and am curious to see where your soldering points were.

Thanks!

cvh
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Re: Too many packets lost error

Post by cvh » Thu Aug 08, 2013 12:15 pm

I've setup a little blog, you can find my experiments here:
http://crazyflie.yankie.be

The soldering point towards the outside of the board comes off when you heat it. It's the soldering point towards the center of the board you need.

absoloodle37
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Re: Too many packets lost error

Post by absoloodle37 » Fri Aug 09, 2013 1:34 pm

Awesome thanks!

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