[theonewithin]

Why are.you trying to communicate using CAN to a Pi?

Connect it via USB and it will just work...

[dazq]

That link I posted to that wiki for OBD2 explains the obd protocol for code readers.
This is currently the ONLY canbus connectivity that functions. The auxin and secondary data stream normally using serial3 does not yet work with canbus.

Please explain what you want the pi to actually get or send in more detail.

[Kubs]

I'm aware that CAN functionality is limited to broadcasting only and this is all what I need for now.
I just need to extend my already working bus by reading data from the teensy.

BUT

It seems that teensy isn't broadcasting anything at all... Candump is empty

In about 5 hours I'll be back home and I'll look on the bus using scope.

[dazq]

OBD2 messages are not a broadcast , they are a command response protocol.
There is no broadcast option in speedy at the moment.
You only need enable the internal can option in the secondary serial setup menu for the can to respond to requests, no other options need be set for testing

[Kubs]

Laugh at me all the way but I still didn't receive any frame


Tried multiple query codes with no result.

I attached my secondary serial config and can0 traffic

Kingdom for an oscilloscope...

[Kubs]

The transceiver TX line is dead. It's in permanent high state. That's why when I tied CAN TX and RX on transceiver together there was still nothing on the candump.

What about my CAN config? Is it any good?

[dazq]

I would suggest you put together a simple send /receive program to test the teensy and pi hardware setup.

The config looks ok.

Try testing the hardware first, you did say that there may be some damage....

[Kubs]

assuming that this can tx and rx are no different from standard uart there should by hardware loopback equivalent after tying up tx and rx together.
dazq would you be so kind to check this assumption?

[dazq]

assuming that this can tx and rx are no different from standard uart there should by hardware loopback equivalent after tying up tx and rx together.
dazq would you be so kind to check this assumption?

I am sorry but no you cannot just bridge tx and Rx together for loopback on canbus, the two wires operate on a differential voltage ,nothing like the serial.

[JHolland]

I did not tie together the ground of teensy and pi together as it is allegedly irrelevant for the bus working - as I found only the transmission speed may vary.

Thats a common mistake (pun intended!), the signals must be within the common-mode range so the 0V should be tied together.
Laptops can be great for blowing up CANBus chips, thats why the standard 'OBD2' socket has protuding 0V connections - to equalise the grounds before the signal lines make contact.
You can't loop the CANBus back like a UART but some CAN chips do have a loopback capability that can be enable in software, check the datasheet.