TMDS570LS12HDK: CAN network using the TMS570LS12X Board

Dinesh Sampath

Part Number: TMDS570LS12HDK

I am trying to develop a CAN network using 4 TMS570LS12x board. Will there be a problem having the termination resistor in all CAN interfaces in all the board. Is there a way to configure remove the termination resistor in the HDK? So that i can remove the termination resistor from 2 board and leave the other 2 board's to terminate the network.

Is there any application based on CAN for the TMS570LS12x HDK?

over 4 years ago

0 Miro over 4 years ago

TI__Mastermind 21425 points

Hello,
The only way to disconnect termination resistors of HDK from the buss is to remove them. Resistors at both line ends are mandatory.
Please take a look at this app note, it may be helpful: www.ti.com/.../slla270.pdf

Best regards,
Miro

0 Dinesh Sampath over 4 years ago in reply to Miro

Intellectual 490 points

Hi Miro,

So i cannot create a network using 4 TMS570LS12x Boards without removing the resistors from 2 of the boards keeping the other 2 for terminate both the ends?

Thanks,
Dinesh

0 Miro over 4 years ago in reply to Dinesh Sampath

TI__Mastermind 21425 points

Hello,
Yes, you should do like this.

Best regards,
MIro

0 Dinesh Sampath over 4 years ago in reply to Miro

Intellectual 490 points

Hi Miro,

Sorry, just want to double check, shouldn't it be a problem connecting 4 TMS570LS12x HDK's with termination resistors in it?

Thanks,

Best Regards,

-Dinesh

0 Miro over 4 years ago in reply to Dinesh Sampath

TI__Mastermind 21425 points

Hello,
CAN bus is using differential line with nominal characteristic impedance of 120Ohm. For that reason line must be terminated at both ends with 120Ohms. You are not terminating nodes but line. This is very important for high speeds and long lines. Termination prevents reflections that might cause communication failure. There should be no more than two terminating resistors in the network, regardless of how many nodes are connected, because additional terminations place extra load on the CAN transceivers.

Best regards,
Miro

0 Dinesh Sampath over 4 years ago in reply to Miro

Intellectual 490 points

Hi Miro,

If i have to use the 4 TMS570LS12x board for my CAN network i will have to remove the resistors from the board except 2. Is this correct?

Thanks,

Best Regards,

-Dinesh

0 Miro over 4 years ago in reply to Dinesh Sampath

TI__Mastermind 21425 points

Hello,

Yes, you should leave only 2 resistors (on both ends) on the bus.

Best regards,
Miro

0 Dinesh Sampath over 4 years ago in reply to Miro

Intellectual 490 points

Hi Miro,

Thanks for your reply. I am planning to order 3 TMS570LS12x HDK's. Is it possible for TI to remove the aforementioned resistors and send to me? Or can you please let me know how to safely remove the resistors from the board for my use case?

Thanks,

Best Regards,

-Dinesh

0 Miro over 4 years ago in reply to Dinesh Sampath

TI__Mastermind 21425 points

Hello,

I am not aware about such procedure. You should ask your local TI representative.

Resistors are with size 0402. Components with this size is not very hard to be removed. Off-course some skills and practice are necessary.

Best regards,
Miro

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TMDS570LS12HDK: CAN network using the TMS570LS12X Board