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TIDM-1000: Sample trigger point configuration

Cherry Zhou
Mastermind 22235 points

Part Number: TIDM-1000
Other Parts Discussed in Thread: C2000WARE

Hi team,

Here's an issue from the customer may need your help:

The software code is located in the following directory: C:\ti\c2000\C2000Ware_DigitalPower_SDK_4_02_00_00\solutions\tidm_1000\f28004x

The sample trigger points are configured as follows:

EPWM_setCounterCompareValue(base, EPWM_COUNTER_COMPARE_B,
           ((uint16_t)((float32_t)VIENNA_PFC3PH_PWM_PERIOD * (float32_t)0.5)
           - (uint16_t)( (float32_t)VIENNA_IL1_ACQPS_SYS_CLKS * (float32_t)6.0
     * (float32_t)(VIENNA_PWMSYSCLOCK_FREQ_HZ / (float32_t)VIENNA_CPU_SYS_CLOCK_FREQ_HZ) )
           - (uint16_t)( (float32_t) VIENNA_ADC_CONV_TIME
               * (float32_t) VIENNA_PWMSYSCLOCK_FREQ_HZ * (float32_t)6.0 ) ) );
1) What does 6.0 mean in the program? Number of sample channels? But the actual sample channels configured in the program are 6 right?
2) Does the Vienna_ADC_CONV_time macro definition represent the sampling time 210 ns? But the conversion times in the 280049 manual are also 290 ns and do not seem to match?
3) Why should the sampling point be configured so? It is not sampling the average current within a period.

Thanks.

Best Regards,

Cherry

  • +1
    TI__Genius 16085 points

    Hi Cherry,

    Cherry Zhou said:
    1) What does 6.0 mean in the program? Number of sample channels? But the actual sample channels configured in the program are 6 right?

    I think this is to compensate the sampling window of ADC(ACQPS).

    Cherry Zhou said:
    2) Does the Vienna_ADC_CONV_time macro definition represent the sampling time 210 ns? But the conversion times in the 280049 manual are also 290 ns and do not seem to match?

    Yes, your are right. This is should be 300ns for f28004x.

    Cherry Zhou said:
    3) Why should the sampling point be configured so? It is not sampling the average current within a period.

    This is just to make sure the the real S/H window is put in the middle of the switching period.

    Regards,

    Cheh