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  #1  
Old 11-10-2017, 01:58 PM
dtw_rv6 dtw_rv6 is offline
 
Join Date: May 2008
Location: Martinsville, IN
Posts: 454
Lightbulb -EXP Deconstructed

I was bored today, and since I fall under the AD that forces me to remove my Navworx -EXP, I spent a few hours on my back with my fuel selector buried in the small of my back (RV6). Here is what came of it:

Remove the EXP


I can't ever resist the urge to tear apart a piece of worthless junk if it has screws in it:


Here is the offensive little piece of silicon (GPS) that we have all heard so much about:


Really? Void my warranty? Ha!


Ah Ha!


That's all for now. If anyone has any ideas on what comes next, let me know. I'm not an electrical engineer, but I do know how to read a cut-sheet. And I'm relentless

Don

Last edited by dtw_rv6 : 11-10-2017 at 02:27 PM.
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  #2  
Old 11-10-2017, 03:24 PM
krw5927 krw5927 is offline
 
Join Date: Aug 2010
Location: Wichita, KS
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Default Next?

A bandsaw could turn it into a nice pair of wheel chocks for your hangar.
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  #3  
Old 11-10-2017, 03:31 PM
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DaleB DaleB is online now
 
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Would be nice to see some hi-res shots of the markings on all of the chips, especially those on both sides of any daughter/mezzanine boards that are screwed onto the main board.

I suppose it's too much to hope for that NW might have used a GPS module with an NMEA interface to the rest of the works that would possibly allow splicing in some other source. Just idle speculating on a dreary Friday afternoon.
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  #4  
Old 11-10-2017, 04:11 PM
dtw_rv6 dtw_rv6 is offline
 
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Location: Martinsville, IN
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Its a consumer grade Sirf IV according to the AD. Its the only chip on the board that doesnt have any sign of identification. Looks like the Sirf supports NMEA... i just have to figure out which pin is the RX and TX.

The bandsaw idea is good. I think it might work better as a Tannerite holder though.

The chip has 6 pins per side... i just started looking at digikey for clues.

Last edited by dtw_rv6 : 11-10-2017 at 04:58 PM.
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  #5  
Old 11-10-2017, 10:39 PM
Timberwolf Timberwolf is offline
 
Join Date: Nov 2016
Location: Navarre, FL
Posts: 385
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Figure out how to wire in the uAvionix gps 1 wire from their all in one WAAS gps puck and we?re set. That?s what I don?t get from this whole thing. It?s an experimental and it?s up to the manufacturer to show that it is up to the standard. I believe you could show that by using known parts that are already accepted as meeting the standards we would be good to go. This is a messed up place the FAA has created as far as certified/experimental. Does anyone have an idea on what the doghouse had or how it bypassed the internal gps?
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  #6  
Old 11-11-2017, 08:12 AM
dtw_rv6 dtw_rv6 is offline
 
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Location: Martinsville, IN
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This is exactly what I'm hoping to discover. My assumption is that Bill was going to reprogram the i/o so that one of the spare pins on the DB9 would become an input for serial data, then disable the onboard chip. Since I probably can't get the firmware code, the only way I can imagine is to intercept the serial traces and re-route them mechanically to the DB9.

1. Altera Cyclone III - EP3C25F324C8N / G_CCAAA1519A
2. Analog Devices AD6652BBCZ / #1526 / 3174726.1
3. CY62167EV3 (3 or 4 more digits unreadable) / 45ZXI 1325 / next line is unintelligible.

The Cyclone is aparently an FPGA with Intellectual Property protection features. I'm not sure I would know how to break that with an electron microscope.....

Quote:
Originally Posted by Timberwolf View Post
Figure out how to wire in the uAvionix gps 1 wire from their all in one WAAS gps puck and we?re set. That?s what I don?t get from this whole thing. It?s an experimental and it?s up to the manufacturer to show that it is up to the standard. I believe you could show that by using known parts that are already accepted as meeting the standards we would be good to go. This is a messed up place the FAA has created as far as certified/experimental. Does anyone have an idea on what the doghouse had or how it bypassed the internal gps?
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  #7  
Old 11-11-2017, 08:22 AM
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1001001 1001001 is offline
 
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Quote:
Originally Posted by dtw_rv6 View Post
...

The Cyclone is aparently an FPGA with Intellectual Property protection features. I'm not sure I would know how to break that with an electron microscope.....
Hey, we are all homebuilders here...

https://makezine.com/2011/03/24/diy-...-microscope-2/
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  #8  
Old 11-11-2017, 09:11 AM
dtw_rv6 dtw_rv6 is offline
 
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Location: Martinsville, IN
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Default GPS Module

The EXP GPS module seems to line up with an Inventek Systems ISM-420-R1. See photo markup:



If that is the case, then I should be able to pump a new GPS signal in on PIN 14. It appears to be a UART (serial data) signal. Pins 4 and 5 configure the baud rate and data protocol with the two resistors being pulled low or high.

Does anyone know of a "safe" way to probe pin 14 to confirm it is a serial line?

I don't have an oscilloscope, but maybe someone else does?

Don
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  #9  
Old 11-11-2017, 09:26 AM
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DaleB DaleB is online now
 
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Quote:
Originally Posted by dtw_rv6 View Post
The EXP GPS module seems to line up with an Inventek Systems ISM-420-R1. See photo markup:



If that is the case, then I should be able to pump a new GPS signal in on PIN 14. It appears to be a UART (serial data) signal. Pins 4 and 5 configure the baud rate and data protocol with the two resistors being pulled low or high.

Does anyone know of a "safe" way to probe pin 14 to confirm it is a serial line?

I don't have an oscilloscope, but maybe someone else does?

Don
I do, but we're a good distance apart.

My Plan A would be the scope. Plan B would be to pick off the signal on that pin, buffer and invert it, and feed it to a PC serial port and see if it's serial data. I have parts for this kind of thing lying around, but most people (normal people?) don't. The easy way is a small-signal MOSFET like a 2N7000 with a pull-up resistor.
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  #10  
Old 11-11-2017, 09:47 AM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
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Quote:
Originally Posted by dtw_rv6 View Post
Does anyone know of a "safe" way to probe pin 14 to confirm it is a serial line?
Don - You could try making a simple data probe using a 2 volt LED diode and 300 ohm resistor. I don't know how to post a graphic in this text so will refer you to page 9 of the ACK E-04 instillation manual. There is a graphic on that page that shows you how the probe is made. If there is data on that line you want to test the LED will flash. This test won't tell you if the line is "serial data" but it may help you determine if the line is polled data. One would think if the flashing or flickering is repetitive it would suggest a serial data line.

Link to the ACK E-04 manual refer to page 9:
http://www.ackavionics.com/pdf/E-04%20REV%201.8%20SINGLE%20PAGE.pdf

Not sure if that will help you ... but it is an inexpensive way to have a look.

Good luck
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Last edited by John-G : 11-11-2017 at 09:55 AM.
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