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TM4C129 CAN bus Bootloader

Robert Greene78
Prodigy 205 points

I am having trouble fully understanding how to setup a CAN bus bootloader using the bootloader API.  I have not found a place to set the node-id or what the default is to be able to communicate.  I also am using a 25 MHz crystal and the bootloader doesn't seem to support above 16 MHz in bl_can_timing.h.  Any help with getting this off the ground would be greatly appreciated. 

  • 0
    TI__Guru**** 244380 points
    Hello Robert,

    Since the boot loader is a flash based boot loader, you can use the USER Config Registers to program a default Node-ID per device and use it in the boot loader to assign a node-id.

    For 25MHz the define section for the CAN_BIT_TIMING needs to be created as the code was initially developed with 16Mhz crystal.

    However, in the data sheet an example Baud Rate of 1Mbps with 25Mhz crystal is given in CAN Section -> Example for Bit Timing at High Baud Rate

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 205 points
    The problem is that my application and tool are running 125 kbps on CAN.
  • 0 in reply to Robert Greene78
    TI__Guru**** 244380 points
    Hello Robert,

    One solution would be to port the CAN example code and use the CANBitRateSet to get the value of the timing registers and then set the same value in the define look up table.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 205 points

    Amit,

    I have decided to use those methods and others to achieve my results while removing the setup inherent to the bootloader. I was hoping to avoid modifying the bootloader api provided too much, but I see no way around it  at this point.