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Original question:

Tiva C CAN bit Timing error

TM4C129ENCPDT: Tiva C CAN bit Timing error

Allef Silva28
Intellectual 365 points
Part Number: TM4C129ENCPDT

Hi all,

I want to ask this question again, please.

e2e.ti.com/.../350758

  • 0
    TI__Guru**** 191826 points

    Hi,

     I don't think the source code is wrong. I think perhaps the variable name could have been defined as ui32PropPhase1Seg rather than ui32SyncPropPhase1Seg because the Sync field is a segment that is always equal to 1 quanta. This is an implied quanta. The hardware will always account for the 1 quanta Sync field when adjusting the nominal bit timing.

    Here is what is shown in the datasheet. Please note that the register field TSEG1, TSEG2 are programmed to a numerical value that is one less than its functional value. If you look at the first equation, the bit time is equal to (TSEG1 + TSEG2 + 3). * tq. You might ask where the 3 is coming from. Since the programmed value is one less than the functional value, the actual functional (Prog+Phase1+Phase2) will be two more than (TSEG1+TSEG2). This accounts for 2. Where is the other 1? That is to account for the Sync which is implied.