code modification for DRV8312GUI_Main.c

user4522670

Other Parts Discussed in Thread: DRV8312

Hi,

I have a DRV8312-C2 Kit and I am running the motor that came with the Kit using DRV8312GUI_Main.c.

Can somebody tell me, how do i modify the code to get 100% duty cycle for the PWMxB signals (the signals fed to the RESET_X input of the DRV8312)? I posted a question regarding current waveform DRV8312 issue on Motor Driver Forum and was asked to modify the PWMxB signals.

Below are some other questions:

Looking at the BLDCPWM_Macro(),

1. what is the function of the variables Tmp and Tmp2?

2. What does half mean in EPwm1Regs.CMPA.half.CMPA = (int16)(Tmp>>15)?

Thanks!

over 10 years ago

0 user4522670 over 10 years ago

Intellectual 690 points

hi, any feedback here?

Looking at the BLDCPWM_Macro(),

1. what is the function of the variables Tmp and Tmp2?

2. What does half mean in EPwm1Regs.CMPA.half.CMPA = (int16)(Tmp>>15)?

0 Jeff Stafford over 10 years ago in reply to user4522670

TI__Expert 4595 points

Hi,

/* Convert "Period" (Q15) modulation function to Q0 */\

Tmp = (int32)v.PeriodMax*(int32)v.MfuncPeriod; /* Q15 = Q0xQ15 */\

Period = (int16)(Tmp>>15); /* Q15 -> Q0 (Period) */\

"Tmp" is the period value represented as the % of (Q15) the max period whcih is an integer (Q0)

"Period" is Tmp (% of max period in fractional form, Q15) represented as an integer (Q0) which is required for loading into the period register

Please refer to additional information on IQmath. http://processors.wiki.ti.com/index.php/IQmath_Library_for_C28x

/* Convert "DutyFunc" or "GPR0_BLDC_PWM" (Q15) duty modulation function to Q0 */\

Tmp = (int32)Period*(int32)GPR0_BLDC_PWM; /* Q15 = Q0xQ15 */\

EPwm1Regs.CMPA.half.CMPA = (int16)(Tmp>>15); /* PWM signal on output B of EPWM1 (Q15 -> Q0) */\

"Tmp " is the PWM duty cycle as a % of (fraction, Q15) the Period (integer, Q0). By right-shifting the 32-bit value of TMP by 15 bits, the fractional bits are dropped and are loaded into the 16-bit compare register. There are additional bits in the compare register that are for HRPWM (high-resolution), the "half" symbol is referencing the lower non-HR bits of the compare registers. You can find more on this in the PWM chapter of the device user's guide.

Thanks,

Jeff

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code modification for DRV8312GUI_Main.c