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TMS320F28035: Program Counter and run cycle

Tobby Guo
Intellectual 770 points
Part Number: TMS320F28035


HI:

A question about instruct MOVW

According the Disassembly code, the PC of instruct MOVW is 0x082c and 0x082d.

The run cycle of MOVW is 1, why the PC is  0x082c and 0x082d.

Any suggestion?  Thanks

  • 0
    TI__Guru* 93100 points

    Tobby Guo said:

    According the Disassembly code, the PC of instruct MOVW is 0x082c and 0x082d.

    The run cycle of MOVW is 1, why the PC is  0x082c and 0x082d.

    Any suggestion?  Thanks

    The MOVW instruction requires a 32-bit opcode. This is why it takes up 2 16-bit memory locations.  The opcode is shown in the reference manual screenshot you posted.

    The cycles are the number of CPU cycles the instruction takes to execute.  The size of the opcode and the cycles required to execute are not the same. 

    Regards

    Lori

  • 0 in reply to Lori Heustess
    Intellectual 770 points

    Lori,

    Thanks for you explaintion.

    The MOVW instruction requires a 32-bit opcode, 0x082c and 0x082d is only memory location. 

    As the screenshot above:

    Is the code read Epwm5Regs.TBCTR take up  6 16-bit memory location from 0x0828  to 0x082d and need 4 machine cycle（MOVW/MOV/MOVW/MOV） to execute?

    Thanks.

  • 0 in reply to Lori Heustess
    Intellectual 770 points

    Lori,

    After I recheck my first screenshot picture， I confuse.

    I continuous read the value of Epmw5Regs.TBCTR four times , the value of u16ISRRunTimer06/u16ISRRunTimer07/u16ISRRunTimer08/u16ISRRunTimer09 is 431/437/443/449, the value add 6 each read

    In my opinion, the value of Epmw5Regs.TBCTR  Increment or decrement  every machine cycle.

    if  read Epwm5Regs.TBCTR need 4 machine cycle（MOVW/MOV/MOVW/MOV） to execute, I think the value of u16ISRRunTimer06/u16ISRRunTimer07/u16ISRRunTimer08/u16ISRRunTimer09 shoud be 431/435/439/443,  the value add 4 each read.

    Any suggestion? Thanks.

  • 0 in reply to Tobby Guo
    TI__Guru* 93100 points

    Tobby,

    A visual inspection gives the best case scenario.   There may be wait-states or pipeline stalls that were not taken into account.  You can try creating a pipeline diagram or you can use the timer values.  I would suggest the latter as it is much easier :) 

    Regards

    Lori

  • 0 in reply to Lori Heustess
    Intellectual 770 points

    Lori,

    Thanks for you reply.

    Is  timer values means the value of  CpuTimer0Regs.TIM.all, I'll try this later.

    Yet, I think TBCTR is also a  effective manner to record the time of machine execute?

  • 0 in reply to Tobby Guo
    TI__Guru* 93100 points

    Yes.  In this context counter and timer are the same.  

    Regards

    Lori