Quadcopter repairs

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rodney_alm
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Location: Goa, INDIA
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Posted by rodney_alm: Fri. Jun 19, 2015 - 05:10 AM
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Hi Guys

 

I crashed my quadcopter cx-20. its seems that the gps/compass unit has been damaged. i noticed that the patch antenna is broken. i wanted to hook this unit to my system and check what does it transmit to the main board.. but i'm not quite sure whats the transmission protocol in use. I assumed it was Serial transmission. so i hooked it to my UART USB bridge.. tried different baud rates but could not get a legible readout.

 

Any ideas? 

 

i have not yet opened the inside of the quadcopter. and the gps unit has just 3 wires. 

 

Rodney Almeida

 

 

Attachment(s): 

Image icon IMG_20150619_103052.jpg
Image icon IMG_20150619_103036.jpg

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Learning and Information, General Electronics
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meslomp
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Posted by meslomp: Fri. Jun 19, 2015 - 05:55 AM
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It will be serial output for sure as there are only 3 wires. Ground, Supply and data out.

 

if it was a standard GPS receiver it should spit out data at 9K6 baud 8-n-1-n

 

quick check on the markings on your board.....

It also has a accelero meter and gyro module, so the output will be something proprietary for sure.

I suggest a search on "bigflyshark protocol" and see if there is anybody that has cracked it.

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awneil
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Posted by awneil: Fri. Jun 19, 2015 - 08:03 AM
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Looks like a uBlox GPS module - see the red logo in the corner

 

http://www.u-blox.com/en/gps-mod...

 

Peel the 'QC passed' sticker off to reveal the part number!

 

If just the antenna is broken, I'd have thought you should still be getting some data out of it - but reporting that it can't get a fix.

 

rodney_alm wrote:
i hooked it to my UART USB bridge

What voltage levels does your bridge use?

 

I'd think it highly unlikely that the GPS uses 5V - could be as low as 1.8V ...

 

 

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillator: https://www.avrfreaks.net/comment...
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Last Edited: Fri. Jun 19, 2015 - 08:07 AM
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Kartman
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Posted by Kartman: Fri. Jun 19, 2015 - 08:04 AM
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The antenna looks broken to me. Besides, the gps probably wont work too well indoors.

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awneil
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Posted by awneil: Fri. Jun 19, 2015 - 08:09 AM
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It would be helpful if you would crop the photos - so we don't have to scroll through the vast expanses of your desk!

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillator: https://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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rodney_alm
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Posted by rodney_alm: Fri. Jun 19, 2015 - 08:36 AM
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Hi everyone,

 

Yes it is indeed the ublox gps module. 

 

i can see data coming out of it. but i am not receiving it right.. my usb bridge is at 5v and if as you say the board will be running at a lower level than im reading it wrong. the bridge uses the ft232rl chipset.. think i can  modify it to work at a lower voltage.

 

let me measure whats the voltage delivered by the quadcopter to the gps unit first.

 

cheers

 

Rodney

 

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