[Mikael74]

I found this on ebay. Would it do the job (except the connectors)? I would like to use main port on the Revo for s.bus communication - is there a problem with that? Think I have red somewhere that I could use flexi and flexi-io for GPS and compass.

http://www.ebay.com/itm/Ublox-NEO-M8N-GPS-Modul-w-Compass-fur-APM2-8-APM2-6-Pixhawk-Flight-RC234-/132022957472?hash=item1ebd2e75a0:g:AQEAAOSwux5YQwyC

[TheOtherCliff]

On Revo you must use MainPort for SBus because SBus requires a hardware inverter circuit and that is only built into MainPort.
On Revo you must use FlexiPort for I2C mag because it is the only port that can do I2C.

[Mikael74]

Ok. And then the flexi-io (which is freed up when I use s.bus) can be used for the GPS. Do you think the GPS I linked to will do the job with a little soldering and new connectors?

[TheOtherCliff]

It should work fine.  I think I have one that looks just like it and really every Ublox GPS with standard APM/Pixhawk mag that I have tried or heard of works.  Some need a little help with I2C pullups.

Just FYI: If you haven't bought it yet, there are GPS/mags that are a bit smaller if you need smaller.
http://www.ebay.com/itm/Ublox-NEO-M8N-Flight-GPS-controller-with-Compass-Engine-PIX-Pixhawk-PX4-/282313226905

But then there is the DJI/Naza GPS/compass which does GPS and compass on a single connector.

[Mikael74]

Smaller and cheaper - whats not to like 

[andyp]

I have also the Ublox Neo M8N and connected the compass to I2C and the GPS to serial like it is described in the librepilot user forum.

Works well and no problems so far, but I have ordered the one connector NAZA GPS with compass in order to use the I2C port for telemetrie for OSD. This is better.

[Mikael74]

Any reason You are not using the built in OPlink in the Revo?

[TheOtherCliff]

Built in mag maybe? 
The problem is that the high current flight power wires are too close to Revo.  An aux mag sensor can be moved farther away from these wires so they don't distort the compass.

[Mikael74]

Yes I know. But I understood that andyp would use the flexi-port (I2C) for telemetry? Maybe its me not understanding the issue.

In my setup I'm using built in OPlink for telemetry. And plan on using the flexi-port for I2C comm. with ext. compass and the flexiIO for GPS. Then use the main-port for s.bus comm with receiver.

I was the curious (since I'm still learning quite a bit here) why the setup mentioned by andyp with NAZA GPS/compass on the flexi-port was better?

[TheOtherCliff]

andyp?  I don't see OpLink/telemetry described.

FYI: S.Bus is an RC receiver protocol on mainport and the receiver port is also called FlexiIO which is different than FlexiPort.