Serial connection between VF61 and Pixhawk2.1

As the title suggests, I was trying to make a serial communication link between a VF61 (currently on an Iris board, later will be move on a Viola) with a Pixhawk2.1 flight controller. On the SoM I have installed the stock Ångström linux and in that i have installed python, pip and the libraries I need (pymavlink and dronekit).
The following test have been conducted both on the UART-C and the UART-B ports of the Iris board. The serial port on the Pixhawk is the 2nd telemetry port(telem2). Tests have been conducted with baudrates of both 921600 and 57600.

Tests have been made to determine the source of the problem but still with not much success

  • python has access to read and write on UART
  • the UART works when tested with "screen"
  • pymavlink works through USB(FTDI cable to Telem2)
  • dronekit tries to establish connection but does never get a response (USB(FTDI) and UART)
  • same version of dronekit works with a computer(FTDI cable to Telem2)
  • if a USB to USB connection is established dronekit works

As you can tell from the test cases above i tried to cover the points in the link where there could be an issue
either with the hardware or the software. Individually the various components seem to work but the desired UART to Telem2 connection seems to be uncooperative. Which is why I’m making a post here.
If someone can give me a hint or a tip to the right direction it would be very much appreciated.

What exact hardware and software versions of things are you talking about?

How exactly did you connect to the UART? Note that the Iris board has RS232 transceiver which might influence your communication when using TTL UART…

I connected through the UART ports in the Extension Connector (X16) which should be unaffected from the RS232 right? I was getting some interference at the UART-B/C header (X14)[probably because of RS232] on Iris but then decided to use pins 34-36 for UART-C and some of the problems were gone.

The Iris board is version 1.1, the Viola is on Rev 1.2 and VF61 is an also V1.2 A. As far as software goes i’m using pymavlink 2.2.5, dronekit 2.9.1 on the OS installed by Colibri-VF_Console-Image_2.7b3-20170702.tar.bz2. The Pixhawk2.1 is the standard version(No EDISON) with firmware version 1.6.5dev(according to QGroundControl)

The UART pins on the Extension Connector X16 are actually affected by the RS232 transceiver. Check the Iris Datasheet (Chapter 3.9 Digital and Analog I/O Interface) and the schematics if necessary.