Reading CAN bus from pixhawk CAN port to RPI

Applications & Usage PyCyphal
1

Hello all,
I am using a RPI 3b+ with a MIKROE CAN to SPI 3.3 volt click board. I am attempting to read RAWIMU through the can bus port on the pixhawk. I am using socket can and was able to test my hardware setup and am able to send an receive messages.
Here is my problem, when I connect my pixhawk to the bus I cant read any CAN messages from the pixhawk. I have setup all the necessary parameters in mission planner. Do I have to send a message before I can start reading?

Any help would be greatly appreciated

2

You need to make sure that the APM is actually publishing the data you are looking for. Consider using a conventional USB-CAN adapter with the GUI tool to test that.

3

Thank you for the reply Pavel,
I meant to ask this question before…
So is it possible to use uavcan.equipment.ahrs.RawIMU to read raw imu data from the can bus port of the pixhawk in arduplane?

I have a USB-CAN adapter too. I will try that next

4

I don’t know. Please ask ArduPlane developers instead.

5

Thanks!

6

I plugged in a USB-CAN adapter and clicked read. I am seeing traffic! The problem is I am only seeing one node id: 1001550A go by at about one Hz. Should I be seeing more then one node id if other sensors are publishing to the bus?

Also I found this test code for publishing
https://github.com/ArduPilot/uavcan/blob/master/libuavcan/test/node/publisher.cpp
Would i have to use this to see other nodes on the bus?

7

This is not a node-ID. This is a NodeStatus message from a node whose node-ID is 10 (0x0A).

Yes. Apparently, the autopilot is not publishing the data you need. I suggest you read the user manual or ask the maintainers why the data you are after is not being published and how to enable it.

No, this is a unit test.

8

Thanks again,
This helps a lot. Looks like I have my work cut out for me. I was thinking the pixhawk was already doing this and the dsdl definitions were directly usable.

Dose the NodeStatus message have anything to do with the UAVCAN DSDL messages?

9

The software is not publishing the data you are looking for.

(there is a terminology issue: when you say “Pixhawk”, you are referring to the hardware, which is not really what you should be talking about; instead, you should be referring to the software stack running on that hardware, such as ArduPilot or PX4; the same stack can be used with other hardware platforms but its feature set is largely invariant to the type of the underlying hardware).

Of course. It’s a standard message type defined by the Specification. It is available in the stable version of UAVCAN as well, but under a different name uavcan.node.Heartbeat.1.0.