Multiple mavlink devices connected to pixhawk on Serial 4/5?

[Alex Jacobson]

Hi,

I am working on connecting multiple mavlink devices to the pixhawk and I had a couple of questions / potential requests. I was hoping to plug in two mavlink devices to a pixhawk as well as the 3dr telemetry module. All of my devices need to send to and receive from the pixhawk so I can't make a splitter and have them all on telem 2. Telem 1 is reserved for the 3dr module and I could put one of my devices on telem 2. I just don't have a way of connecting them all to the pixhawk and having them all send and receive commands. 

That leads me to my question: Is it possible to connect to the Serial 4/5 port on the pixhawk and send and receive mavlink commands over that. I couldn't get it to work myself and it seems like its not setup for that. Has anyone gotten that to work? Will that be added to the flight code any time soon? Could it be?

Any help regarding this would be great. 

Thanks,

Alex

[Craig Elder]

At the moment you can transmit Mavlink from the Pixhawk on both Telem1 and Telem2 and you can receive mavlink commands into the Pixhawk on Telem1.  Two of the remaining serial ports are 2x GPS input only.  That leaves Serial 5 which is the Nuttx terminal only.  We don't have any plans to change that but we always welcome pull requests

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[Kristian Klausen]

What about USB connector, it can be used the same time as the telemetry ports, right?

[Meier Lorenz]

Hi Kristian,

The USB connection has not been designed as in-flight feature and has not been tested as such. USB in general is a consumer bus and you run into a lot of stability problems (even on full-blown systems like MacOS within the operating system - just close a MacBook’s lid, unplug the (connected in software) FTDI cable and watch the hang and reboot unfold - this is entirely unrelated to our autopilot, just an example of the inherent complexity and failure cases of the bus). Given that major players like Apple still struggle with that bus, we’re not going to declare our end on the autopilot airworthy any time soon.

-Lorenz

On 15 Aug 2014, at 10:16, Kristian Klausen <kkn...@gmail.com<mailto:kkn...@gmail.com>> wrote:

What about USB connector, it can be used the same time as the telemetry ports, right?

kl. 05:04:45 UTC+2 fredag 15. august 2014 skrev Craig@3DR følgende:
At the moment you can transmit Mavlink from the Pixhawk on both Telem1 and Telem2 and you can receive mavlink commands into the Pixhawk on Telem1. Two of the remaining serial ports are 2x GPS input only. That leaves Serial 5 which is the Nuttx terminal only. We don't have any plans to change that but we always welcome pull requests

On Thu, Aug 14, 2014 at 4:13 PM, Alex Jacobson <alexjac...@gmail.com<javascript:>> wrote:
Hi,
I am working on connecting multiple mavlink devices to the pixhawk and I had a couple of questions / potential requests. I was hoping to plug in two mavlink devices to a pixhawk as well as the 3dr telemetry module. All of my devices need to send to and receive from the pixhawk so I can't make a splitter and have them all on telem 2. Telem 1 is reserved for the 3dr module and I could put one of my devices on telem 2. I just don't have a way of connecting them all to the pixhawk and having them all send and receive commands.

That leads me to my question: Is it possible to connect to the Serial 4/5 port on the pixhawk and send and receive mavlink commands over that. I couldn't get it to work myself and it seems like its not setup for that. Has anyone gotten that to work? Will that be added to the flight code any time soon? Could it be?

Any help regarding this would be great.

Thanks,
Alex

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[Kristian Klausen]

Hi Lorenz, thanks for the clarification.

I havn't flown with the pixhawk yet, but currently we are flying apm 2.6 connected to a companion computer through USB. I agree on the bus itselves, but does things change dramatically in that regard moving to the PX4 platform?

Kristian

kl. 14:45:03 UTC+2 fredag 15. august 2014 skrev Lorenz Meier følgende:

Hi Kristian,

The USB connection has not been designed as in-flight feature and has not been tested as such. USB in general is a consumer bus and you run into a lot of stability problems (even on full-blown systems like MacOS within the operating system - just close a MacBook’s lid, unplug the (connected in software) FTDI cable and watch the hang and reboot unfold - this is entirely unrelated to our autopilot, just an example of the inherent complexity and failure cases of the bus).  Given that major players like Apple still struggle with that bus, we’re not going to declare our end on the autopilot airworthy any time soon.

-Lorenz

On 15 Aug 2014, at 10:16, Kristian Klausen <kkn...@gmail.com> wrote:

What about USB connector, it can be used the same time as the telemetry ports, right?

kl. 05:04:45 UTC+2 fredag 15. august 2014 skrev Craig@3DR følgende:
At the moment you can transmit Mavlink from the Pixhawk on both Telem1 and Telem2 and you can receive mavlink commands into the Pixhawk on Telem1.  Two of the remaining serial ports are 2x GPS input only.  That leaves Serial 5 which is the Nuttx terminal only.  We don't have any plans to change that but we always welcome pull requests




On Thu, Aug 14, 2014 at 4:13 PM, Alex Jacobson <alexjac...@gmail.com<javascript:>> wrote:
Hi,
I am working on connecting multiple mavlink devices to the pixhawk and I had a couple of questions / potential requests. I was hoping to plug in two mavlink devices to a pixhawk as well as the 3dr telemetry module. All of my devices need to send to and receive from the pixhawk so I can't make a splitter and have them all on telem 2. Telem 1 is reserved for the 3dr module and I could put one of my devices on telem 2. I just don't have a way of connecting them all to the pixhawk and having them all send and receive commands.

That leads me to my question: Is it possible to connect to the Serial 4/5 port on the pixhawk and send and receive mavlink commands over that. I couldn't get it to work myself and it seems like its not setup for that. Has anyone gotten that to work? Will that be added to the flight code any time soon? Could it be?

Any help regarding this would be great.

Thanks,
Alex

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[Kevin Hester]

re: connecting to a companion computer

I agree with lorenz.  You can use the 'easy' USB connection for initial experimenting, but for in flight if your companion computer doesn't have a 'raw' serial port just use a little FTDI dongle to let you connect to one of the telem ports on the pixhawk.   You will be happier. ;-)

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[Alex Jacobson]

Thank you for all the replies! I'll see if I can create a worthy pull request so that I can have multiple devices on the pixhawk. Thanks again!

[Philip Rowse]

great response Lorenz :) very well put.

Philip Rowse

Electronics Engineering Dept

3DRobotics

Ballarat

Australia

[Bill Bonney]

Maybe you can explain more specifically what devices you have connected. If your devices are only sending one device at a time, a splitter will work. If not you have other options. 

Option 1: daisy chain you devices together, A <-> B <-> C<->D and have message passed along.

Option 2: Use I2C/or SPI devices.

Option 3: Multiplex you signals https://www.sparkfun.com/products/9056

If you can 'combine' mavlink streams as they have identifying fields for sender/receiver, so that's an option. Maybe using a small uController with multiple serial ports that combine messages to a single stream to the Pixhawk

Anyway, just some food for thought.

Bill

[Randy Mackay]

 

     Serial 4/5 are currently reserved for the debug console and the 2^nd GPS.  I’m sure it’s possible to allow them to be used as mavlink serial ports but I don’t know of any specific plans to enable that at the moment.  This would probably require adding some more SERIAL_TYPE parameters like we’ve done to allow Telem1 to be used as an FrSky telemetry port instead of a mavlink port.

 

-Randy

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[Jimson Zhu]

Hi Randy,

I am going to use pixhawk's SERIAL4/5 to connect something like sonar, but I cannot find where to check the message which my sonar sent or pixhawk sent to sonar.I hope you can help me out, thanks.

 

Jimson
在 2014年10月15日星期三 UTC+8上午11:19:34，Randy Mackay写道：

[Basti K.]

Hi I have the same problem.
I am missing a third interface for HoTT telemetry.
Could this help?

nsh> mavlink start -d /dev/ttyS3 -b 57600

Using PX4 Stack