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Permalink Reply by Vernon Barry on April 15, 2012 at 12:30pm

Ok, the basics are that the OSD boards (doesn't matter which "brand"), plugs into the same serial port from the ardupilot as your telemetry modem (Xbee, the new ones or any wireless bridge setup). The OSD board really only needs to receive, where the modem will both transmit and receive. The bottom line is that you screwed up the wiring. Whatever you connected is either shorting that serial out, and/or you did not connect the modem solution correctly.

Both boards (OSD and Modem) more or less get connected in parallel with each other to the serial port. (Think like a y splitter). The OSD receives the exact same packets as mavlink thus you might not be getting any data on either one.

 

See this thread http://diydrones.com/forum/topics/getting-params-sys-id-compid-id-e...

 Better thread: http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A5272... 

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Permalink Reply by Vernon Barry on April 15, 2012 at 1:00pm

See here: http://diydrones.com/forum/topics/minimosd-wiring

The picture says some important info, "DO NOT CONNECT TX when using with Xbee"

So recap: the only wires from the APM to the OSD will be 5v, gnd, and RX, but the Xbee is also conenct to the APM normally with all 4 wires , 5V, GND, RX, TX!!!

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Permalink Reply by Stone1295 on April 15, 2012 at 3:32pm

Thanks for the replies!

 

I've read through the posts you've linked and have tried what you have suggested but I still get the same "Waiting for MAVLink Heartbeats..." message.

 

You can even remove the Tx and Rx wires and the video will still work but you will still receive the message.

 

I've tried Tx on the OSD to the Rx on the APM as well as the reverse of that. 

I've tried Tx to Tx and Rx to Rx as well.

 

Any more suggestions?

 

-Mike

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Permalink Reply by Stone1295 on April 15, 2012 at 10:41pm

So, at the end of the day I'm happy to say that I got this solved! I'm going out to buy myself a candybar!

I was doing a couple of things wrong but the main two were that I was bench testing using power over the USB to power the APM (I was also using a battery to power the camera as specified in the Wiki drawings.), and I was only linking the APM to the MinimOSD with no other servos connected.

To fix all of this I mounted the APM/MininOSD assembly into a plane, plugged in the servos and esc to the APM, the APM connections into the Rx, connected the MinimOSD, and then the camera and Tx to the MinimOSD and fired it all up. It worked!

The connections I made between the MininOSD and the APM were:
APM +5 to MininOSD +5
APM GND to MinimOSD BLK
APM Tx to MinimOSD Rx

I'm not sure about the APM GND to MinimOSD BLK though, the photos in the Wiki show this connection but I'm wondering if the GND on the OSD would be better?

I hope this helps someone else!

-Mike

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Permalink Reply by Stone1295 on April 17, 2012 at 1:33pm

Ok, more testing!

 

It's just the connection of the USB cable that causes this.

 

Am I the only one that has ever had this problem?  :-)

 

-Mike

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Permalink Reply by Vernon Barry on April 18, 2012 at 7:45am

FYI, when using USB power, some sections of the APM are not powered and it's possible you just happened to use those pins are part of your OSD power scheme. The reasoning is that USB only can provide about 500ma of 5V power and thus backfeeding the ESCs, servo outputs and a number of things could cause a brownout or the USB port to just shut down. APM 2 has at least one diode just for this purpose such that USB will not feed the ouputs 5 volt rail.

So somewhat the answer is yes, other people have experienced problems when running from USB only when they did not know the limits of what's powered and not. Sorry I don't have the specific of what's powered and not, but it shouldn't be too hard to test and see no output on the 5V rails rather quickly.

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Permalink Reply by Ovidiu Sopa on May 29, 2012 at 10:55pm

I having the same problem and also removed the USB and powered the APM2 board using the HK 3A BEC, it should provide enough power for all the sistem.

I posted a few pics on another thread, any help is appreciated!

http://diydrones.com/forum/topics/minimosd-with-apm-2-problem?comme...

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