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MSPM33C321A-Q1: mcan_single_message_tx some issue

Colombo Carlo
Mastermind 25735 points

Part Number: MSPM33C321A-Q1

Hi Everybody , 

I m on M33 Launchpad ,  using the mcan_single_message_tx   out of the SDK  - and Launchpad is stdalone ( I dont have a CAN analyzer ) 

I was expeting to be able to see 1 message on CAN everytime I press the Button :  now I can see the first one  and only  it -  so just one message 

there is no Breakpoint set 

please where am I wrong ? why I cannot see  after another button press anothe rmessage ?  ( fyi I checked and any time I press the button  it is recognized by the code ) 

thank you 

BR
Carlo

 

  • 0
    TI__Prodigy 350 points

    Hi Carlo

    The CAN protocol requires Acknowledge (ACK) from at least one other active node on the bus. When you transmit a message, the MCAN module waits for an ACK bit.
    Since your LaunchPad is operating in standalone mode without a second node (like another LaunchPad or a CAN Analyzer) connected to the bus, the first message is sent but never receives an ACK.

    I want to confirm how do you configure in CCS and if you use Internal Loopback Mode?

    Thanks and Best Regards,

    Ella Tang

  • 0 in reply to Ella Tang
    TI__Mastermind 25735 points

    Hi Ella 

    thank you 

    I just loaded the example , run it and check the CAN line : I repush the button  but no frame out -  is it correct ?

    I tried to debug and pressing the button is detected  but MCU hangs .

    coudl you kindly confirm you see the same ?     

    can I force  CAN TX to run  everytime I press the button  - even if std alone the launchpad ?

    FYI in loopback I tested  but I cannot  see any frame out on the pin (  to me makes sense  since  internal loopback ) 

    any help is very welcome 

    thank you 

    BR
    Carlo

  • +1 in reply to Colombo Carlo
    TI__Prodigy 350 points

    Hi Carlo,

    Could you please show me how you check the CAN line and your observations? I am not sure how to reproduce the situation.

    By the way, I found In MCAN setting, we have "Messages Will Only Be Sent Once", this function can disable Automatic Retransmission, if you enable this, could you have any new observation?

    Thanks and Best Regards,

    Ella Tang

  • 0 in reply to Ella Tang
    TI__Mastermind 25735 points

    Hi Ella , 

    thakn you  , the one shot message was the reason 

    thank you 

    BR
    Carlo