CCS/TMS320F28379D: Why frequency of PWM Pulses becomes double when CLKDIV and HSPCLKDIV values are same

Tushar Nistane

Part Number: TMS320F28379D

Tool/software: Code Composer Studio

Hi,

My EPWM CLOCK is at 100 MHz and TB clock at 1.5625 MHz (i.e. CLKDIV and HSPCLKDIV both divided by TB_DIV_4 ( 100 M / 8*8)),

from the TRM given for F28379D, while calculating FPWM (1/2*TBPRD*Time of TB Clock(1/1.5625M)), when both CLKDIV and HSPCLKDIV are set at same value, i am getting my frequency doubled than it should be. Why so ?

For other combination of CLKDIV and HSPCLKDIV it is coming correct.

By default it is given in TRM that CLK_DIV is set at TB_DIV_1 (i.e. 000/1) and HSPCLKDIV at TB_DIV_1 (i.e. 001 / 2).

Please suggest asap.

over 5 years ago

0 Nima Eskandari over 5 years ago

TI__Guru 52020 points

Are you using a launchpad or control card or custom board?

0 Tushar Nistane over 5 years ago in reply to Nima Eskandari

Intellectual 325 points

I am using launchpad with some extension board for more adc channels

0 Nima Eskandari over 5 years ago in reply to Tushar Nistane

TI__Guru 52020 points

Can you share a screenshot of your “predefined symbols” in your project properties compiler setting?

0 Tushar Nistane over 5 years ago in reply to Nima Eskandari

Intellectual 325 points

Yes, sure. But I am using C2000 ware version 2_00_00_3 inbuilt code example of Epwm_up_down_counter. Here is the screenshot of predefined list symbols in header file:

0 Tushar Nistane over 5 years ago in reply to Tushar Nistane

Intellectual 325 points

Here is the project properties predefined symbols, but nothing is listed in there:

0 Nima Eskandari over 5 years ago in reply to Tushar Nistane

TI__Guru 52020 points

Add the predefined symbol to project properties _LAUNCHXL_F28379D

Nima

0 Tushar Nistane over 5 years ago in reply to Nima Eskandari

Intellectual 325 points

so till now if TB_DIV_1 and TB_DIV2 is not defined then what values program was taking, when I have assigned these lines to bit ? How do i define them , like in decimal or binary ? I mean the assigned values should be pre-scaling values or bit values ?

0 Nima Eskandari over 5 years ago in reply to Tushar Nistane

TI__Guru 52020 points

Those are defined and available in your epwm header files. That is not what we changed above by adding the macro. The macro actually corrected your SYSCLK frequency. Please review http://www.ti.com/lit/ug/spruhm8i/spruhm8i.pdf for more information on the EPWM registers.

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CCS/TMS320F28379D: Why frequency of PWM Pulses becomes double when CLKDIV and HSPCLKDIV values are same