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Original question:

LAUNCHXL-F28P65X: Simultaneously read MCAN_A and CAN_A for LAUNCHXL-F28P65X

LAUNCHXL-F28P65X: Write on MCAN on a LAUNCHXL-F28P65X even possible

Isabella Flor
Prodigy 50 points
Part Number: LAUNCHXL-F28P65X

Tool/software:

Good evening!

I am trying to read MCAN mesages using a LAUNCHXL-F28P65X Launchpad, which has only one CAN Transceiver routed to the GPIO 4/5.

I have routed the MCAN bus to those pins 4/5 to read MCAN messages from the bus and print their content on the SCI (UART) port using Simulink and the C2000 Blockset.
However I receive no data even though I think I have everything correctly configured and connected.

I tested the connections sending CAN messages with the same hardware setup and configured as well the files correctly.

However no message is outputted on the SCI port.


Is it even possible to connect MCAN to the CAN Tranceiver and read messages from it for a TI F28P65 Launchpad or does it only supports CAN?

With best regards,

Isabella Flor

  • 0
    TI__Mastermind 37760 points

    Hi Isabella,

    F28P65x has both DCAN and MCAN modules.  I have also answered your other post where you were inquiring if DCAN and MCAN frames can simultaneously transmit frames on a CAN bus.  My response was that this is not possible due to compatibility issues with the frame structure.  From your description, it looks like you are only reading data from the CAN bus and if this is the case it would be possible for both the DCAN and MCAN to read the data provided that:

         - The data available in the CAN bus is using the Classic CAN format (DCAN)

         - The bit timing of the data that is transmitted on the CAN bus is same as the bit timing of the DCAN in F28P65 and the MCAN in F28P65.  For instance, if the Classic CAN frame that is transmitted in the CAN bus is 500kbps, DCAN has to be configured to be 500kbps and MCAN should also be configured with 500kbps NOM rate and 500kbps DATA rate.

    One caveat though, if using GPIO4/5 for CANRX/TX, only one mode will be supported only DCAN or MCAN at one time since the GPIO mux value that assigns pin functionality can only support one mode.

    Regards,

    Joseph 

  • 0 in reply to Joseph Casuga
    Prodigy 50 points

    Hi Joseph,

    Thank you for your fast reply!

    I think that is exactly what I want to do. I want to receive data from a 2 CAN / MCAN busses, both containing only messages in a Classic CAN format. So I can use for one bus the CAN_A pins to receive the messages and use simultaneously the MCAN_A pins to read the Classic CAN data from the 2nd bus.
    I have to ensure that the bit timings / baud rates are the same and that should it so.

    Do the CAN_A and the MCAN_A pins not use the same CAN Transceiver? I thought that might cause some trouble. 

    Best regards,

    Isabella

  • +1 in reply to Isabella Flor
    TI__Mastermind 37760 points

    Hi Isabella,

    The resources that are available in the F28P65x are limited jut to demonstrate basic capability of the device.  There is only one transceiver installed that can interface to one CAN (either DCAN or MCAN) at one time to the CAN bus.  To accomplish what you want, there needs to be another transceiver.    How this will work is that you assign MCAN_A to use GPIO4/5 for CANTX/RX and for CAN_A, choose another set of GPIOs.  Refer to the datasheet for the mux options (Table 5-7 GPIO Muxed Pins) supported for CAN_A.  From the mux table, you can see that CAN_A can also use GPIO30/31 for CANRX/TX.  Let the other transceiver connect to GPIO30/31 and connect the CANL/CANH output of the new transceiver to CANL/CANH of the existing transceiver.  This way the 2 CAN types can operate independently via the same CAN bus.

    Regards,

    Joseph