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Author Topic: AM3352-SOM-EVB: CAN bus between two identical boards  (Read 666 times)

aleks

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AM3352-SOM-EVB: CAN bus between two identical boards
« on: February 12, 2018, 02:50:53 PM »
Hello!

My question is how to connect two AM3352-SOM-EVB boards? My question is in terms of physical connection and software configuration during normal operation of the OS (kernel 4.4.x) or before building the kernel and the dtb files. Do I have to add any other HW, since there is already a controller (DCAN) and a transceiver (SN65HVD230)? All I want is to exchange packets between the two boards as I am monitoring each CAN interface via "candump" tool.

Thanks!

LubOlimex

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Re: AM3352-SOM-EVB: CAN bus between two identical boards
« Reply #1 on: February 12, 2018, 03:09:58 PM »
Alex, I received your e-mail but I haven't had the time to respond. It is probably a software configuration or multiplexing issue.

One thing that might make a difference is that the CAN_T jumpers should be closed on both boards. The reason that it is open by default is because it should be closed only on the first and the rest boards in a CAN network. So if you have ten boards only the first and the last should have CAN_T closed, the other eight in the middle should have it open. In the case of only two boards, close CAN_T of each board.

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aleks

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Re: AM3352-SOM-EVB: CAN bus between two identical boards
« Reply #2 on: June 06, 2018, 08:51:20 AM »
Hi.
I made some research on CAN bus and it says that the terminating resistors are mandatory when the bus is long or it is getting longer. But what about my case, when the bus between the two identical boards is just about 30cm? Do I have to solder the terminating resistors on both boards or it should be working with open resistors on such small length?
Thanks!

LubOlimex

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Re: AM3352-SOM-EVB: CAN bus between two identical boards
« Reply #3 on: June 06, 2018, 09:38:06 AM »
CAN_T should be closed on both boards (or in a setup with more than two boards, CAN_T should be closed on at least two). The length of the wires doesn't matter.

You don't have to solder resistors, just solder the pads of the CAN_T jumper together.
Technical support and documentation manager at Olimex