CAN Bus TX-RX

Gil Fine

Other Parts Discussed in Thread: TMS570LS20216, HALCOGEN

hi again,

Im using the TMS570LS20216

when I use the CanTransmit () function I see the TrReqX and TrReq34 (mailbox=33) are set according to the mailbox number,

same is for NewDatX and NewDat34. (I configured the external loopback test mode).

then I am trying to read using the canGetData() function, and it clears NewDatX and NewDat34 but the TrReqX and TrReq34 are still set.

because the TrReqX and TrReq34 not cleared I cannt transmit once again to the same mailbox (33).

Do TrReqX and TrReq34 should be cleared to transmit again to same mailbox? if yes, what clears it?

One more Question: During the transmition I use an osciloscope to check the CANH and CANL pins (I have the USB Stick EV),

but I see nothing although I used the External loopback. why?

thanks alot

Gil

over 14 years ago

0 Jean-Marc Mifsud over 14 years ago

TI__Mastermind 22375 points

Gil,

I'm working on your question and will be back to you as soon as possible.

Thanks and Regards,

Jean-Marc

0 Jean-Marc Mifsud over 14 years ago in reply to Jean-Marc Mifsud

TI__Mastermind 22375 points

Gil,

I did some test to reproduce your environment and I don't see your problem.

In DCAN to enable the external Loop Back mode, you have to:

1] Set TEST (bit7) in DCANCTL at offsett 0x00.
2] Set EXL (bit8) in DCANTEST at offsett 0x14.

While in this mode, the DCAN will be able to transmit and receive, even if CANL and CANH are not connected to a real network.

Once the data is transmitted, the TxReqX is automatically cleared.

Please can you confirm that your loop back mode was set as explained?

Thanks and Regards,

Jean-Marc

0 Gil Fine over 14 years ago in reply to Jean-Marc Mifsud

Prodigy 100 points

Hi Jean-Marc,

I had anther problem, the message obejects were not configured well.

after some changes i succefully transmit from message object 1 with ID=1 and receive the data on message object 2 also with ID=1.

thanks any way,

Gil

0 Jean-Marc Mifsud over 14 years ago in reply to Gil Fine

TI__Mastermind 22375 points

Gil,

Are you using Halcogen to generate your CAN init?

If you consider this problem fixed, please can you close this thread by clicking on the green answered question.

Thanks for using our forum.

Regards,

Jean-Marc

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CAN Bus TX-RX