I've just received a 3DR GPS with compass module and I'm trying to hook it up to my APM2. I am a bit confused as to which connections I need to make and I was wondering if anyone could clarify this for me. I'm thinking of splicing the cables coming from the module to the pin headers on the APM2 but I can't find a pinout for the 6-pin GPS or the 4-pin compass connectors. The Eagle files in the store are still for the older GPS-only version of the module. I'd be very grateful if anyone of you could point me to the correct pinout for both connectors.
Also, according to the description in the 3dr store, the GPS/compass module has an onboard 3.3V regulator. Does that mean that I only need to provide the GPS with +5V (and don't run an additional +3.3V line from the I2C port on the APM to the compass?)
What version of the APM do you have? Is it just a 2.0 and not a 2.5/2.6?
The Arducopter Wiki will show you how to attach the GPS/ compass to all three versions of the APM: http://copter.ardupilot.com/wiki/common-installing-3dr-ublox-gps-co...
Thank you for your kind reply. I have an APM 2.0. I've read through the instructions but I was still a bit stumped because my APM does not have the DF13 connectors for the GPS / mag like the later hardware revisions. In the mean time, I've measured the pins on the GPS module and think they hook up like this:
Holding the module so that the connectors are on top (and the antenna at the bottom).
For the 6pin GPS connector, from right to left:
VCC (red cable)
GND (leftmost black cable)
And for the magnetometer connector, again from right to left
+3.3V (red cable)
GND (leftmost black cable)
Does this sound about right to you? Do you know why the GPS part of the module is connected to the APM with 5 wires? It appears that four wires would be enough (VCC, RX, TX, GND) and the 5th wire isn't connected to anything?
I believe that the reason for the GPS connector having the extra wire is for programming when using an FTDI to GPS adapter cable. I actually only have five wires on the GPS connector even though it is a 6pin connector. Where did you get your connector wire orientation from? According to the Arducopter Wiki your compass pin orientation appears to be correct: http://copter.ardupilot.com/wiki/common-external-magnetometer-for-i... As far as the GPS goes here is what the PX4 Wiki says about the GPS connector: http://plane.ardupilot.com/wiki/common-px4fmu-overview/ which is similar to your GPS pin signal descriptions.
Did you have success with this? I found an APM 2.0 and had a spare GPS w compass module and would like to do the same. Could you perhaps draw a wiring diagram if you succeeded (and photos pls)?
Unfortunately, I didn't have the time to try it out. I will post the wiring diagram as soon as I get the GPS module working!
I finally got around to playing with the gps+compass module. It appears to be working nicely with my APM 2.0.
Thank you very much for the helpful info. It makes sense that the extra wire is for FTDI programming. I figured out the wire orientation by looking at the APM 2.5 board layout in Eagle and checking how the cables from the GPS+mag module attach to their respective connectors on the APM. I also double-checked by probing for continuity between the solder pads and the DF13 connectors on the module itself.
Attaching the gps+mag module to your APM2.0 is relatively straightforward. I chose to make new connector cables, but you could also modify the cables that came with the gps+mag module or possibly even solder wires to the solder pads on the module.
1. Attaching the GPS
My cable uses the original 6-pin Hirose DF13 connector to connect to the GPS part of the module. I soldered a 4-pin section of header pins to the GPS/UART1 pads on the APM and used a Molex C-Grid connector on this end of the cable. I got the connectors from Distrelec in Switzerland, but you should be able to buy them from the usual suppliers. You only need to run 4 separate wires (TX, RX, 5V, GND) to connect the APM to the GPS. Please refer to the pictures below for the wiring. You probably also need to disable the APM's internal GPS by shorting two pins on the daughter board: http://code.google.com/p/arducopter/wiki/GPSDisable
I didn't manage to do this last step yet.
2. Attaching the compass
Wiring the compass part is more or less the same as above, except that the compass uses a smaller, 4-pin DF13 connector. I soldered a 4 pin header to the pads of the I2C port on the APM and ran all 4 wires (SCL, SDA, 3.3V, GND) to the compass connector (See pictures below). You also need to cut a tiny trace on the APM daughter board to disable the built-in compass: http://copter.ardupilot.com/wiki/common-external-magnetometer-for-i...
Note that this modification could be difficult to reverse (there is very little space) and you might be stuck with a permanently disabled onboard compass.
Ok, a bit of a strange one.
I've got the new HK mini version, and somewhat annoyingly, you need to use a 4 way DF13 to the 6 way on the new 2.6 3DR GPS/compass unit. You can see them on the left here, either side of the USB.
I've followed these instructions, and everything "looks" ok...I get full compass operation, I get the blue flashing light on the unit to signify GPS lock...but the HK mini doesn't seem to see the unit? The HK mini blue light just sits there flashing.
I tried swapping the tx and rx, and the HK unit just sits there, slowly cycling the green and blue LED's.
The wiring seems solid - + and GND work ok, afterall...but what voltages should I be seeing across rx and tx?
The 2.6 was lifted right out of an operating craft, so that's ok.
Edit: Scratch that - i'm talking b****xs again. It's all working now.