Primarily for general aviation discussion, but other aviation topics are also welcome.
User avatar
By ThePipster
Like the Garmin unit above this will provide GPS position data, but without a route that isn't really a lot of use......

I personally would avoid bluetooth based systems as a simple hardwire connection has less to go wrong.

I have looked at the same problem myself and it is just a shame that SkyDemon doesn't provide the NMEA data needed to drive an autopilot. Perhaps drop Tim a line?

User avatar
By gyrotyro
santon wrote:Hi

I have a permit plane with a Trio autopilot that needs an NMEA data source. Until now I have used the output from a Lowrance GPS. However I now propose to use Skydemon as my main GPS with a small AV8R as backup. As the data output from the AV8R uses a microUSB plug and I am forever having problems with bad connections with said plugs I would like another data source.

Would something like this

with the usb plug cut off to reveal the power wires and the NMEA output wires be the best solution please?

Hi Santon,
Like you I have an AV8OR GPS which I want to connect to a Trio EZ pilot control head. The AV8OR has a USB output but the EZ Pilot has a 25 pin D.Sub connector.

Have you found a way of making an interface between the two components?

This is what I have found....
User avatar
By Paul_Sengupta
Not sure if the output is the same as the AV8OR Ace, but this is the manual for that:

It says the USB port can be used for one or two RS232 ports.

Under Optional Equipment it lists:

3 005-03702-1017 Single RS 232 Serial Cable (90 degree 10 pin mini USB to single DB9 male connector)

4 005-03702-1027 Dual RS232 Serial Cable (90 degree 10 pin mini USB to dual DB9 male connectors)

Whether you can find one or not is another matter!

Well, a bit of googling...

Once you've got both ends talking RS232 then you just need something to connect the two.

Just done a bit more googling.

It's a multi-function connector on the Trio. You might need to make up a special cable. it looks like pin 3 from the GPS RS232 goes to pin 7 on the Trio and pin 5 from the GPS adaptor goes to pin 8.
Last edited by Paul_Sengupta on Fri Jul 12, 2019 7:48 pm, edited 1 time in total.
User avatar
By gyrotyro
Thanks Paul, I should have said that I already have that information.

With a usb to RS232 connector I would still need another RS232 connector with a bare wire to connect to the 25 pin D Sub on the AV8OR.

I think my find shown in my OP is the solution but wanted to find out if SANTON had already been down the same route.

Thanks for your Googling. Appreciated.
By santon

As I said earlier I am not a lecktricity bod.

But the Trio control head has a 25 pin socket that connects it to the servos etc and has a wire ( green from memory) that receives the NMEA feed. I just connected this to the NMEA output wire from the Garmin 90 that I am using.

However the screen on the Garmin went funny recently so I bought a GPS dongle (5v)with an RS232 plug on the end to use instead. I chopped off the plug and connected the live and earth to a USB plug/cig lighter socket and the NMEA output wire to the green wire of the Trio.

It didn't work!

The output from the dongle is fine but it only outputs position. I established from Trio that the autopilot also requires a route input even if no route has been set ( ie. a line of zeros). Obviously a dongle cannot be set for a route and so you need a GPS unit that can be programmed and output one.

My understanding ( which is limited) is that the output from a USB is different from RS232 and may not work but please check with someone who understands these things. Don't forget that the output needs to be 4800 baud.