TMDXIDDK379D: fcl_f2837x_tmdxiddk pwm update confusion

Arun Kumar

Expert 1030 points

Part Number: TMDXIDDK379D

Tool/software:

Hello Experts,

Could you kindly give us clarity on the below:

Looking at the tmdxiddk FOC project located at :

there is a function "configurePWM()" which configures the 3 PWM channels.

In this function the PWM channels are configured in shadow load mode using the EPWM_setCounterCompareShadowLoadMode() function(CMPCTL [SHDWAMODE] = 0)

Later down the main function, the FCL library function "FCL_initPWM()" sets the PWM channels to immediade load mode(CMPCTL [SHDWAMODE] = 1), Could you please explain why is this done ?

Isnt shadow loading prefered over immediate loading as the PWM CMPA/B is loaded as perticular events only?

over 1 year ago

0 Arun Kumar over 1 year ago

Expert 1030 points

Any help on the above..pls

0 Jiaxin Teng over 1 year ago in reply to Arun Kumar

TI__Expert 5910 points

Hi AK,

Arun Kumar said:
Later down the main function, the FCL library function "FCL_initPWM()" sets the PWM channels to immediade load mode(CMPCTL [SHDWAMODE] = 1), Could you please explain why is this done ?

Your observation is correct. In the FCL example you referred to, the PWM is updated immediately at the end of every current loop calculation without shadowing. We configure the PWM update in this way to achieve the FCL. You can refer to Chapter 4: Outline of the Fast Current Loop Library in the documentation along with the solution for more details.

Thanks,

Jiaxin

0 Arun Kumar over 1 year ago in reply to Jiaxin Teng

Expert 1030 points

Hi Jiaxin,

I did read through that chapter, but that did not help clear my question, Why configure it in shadow mode in the first place , only to later disable it and enable immediate mode?

Why not configure it in immediate mode directly..

0 Jiaxin Teng over 1 year ago in reply to Arun Kumar

TI__Expert 5910 points

Hi AK,

You can directly configure it as non-shadow mode. The repeat configuration is because we reuse the ePWM configure function in other examples.

Thanks,

Jiaxin

0 Arun Kumar over 1 year ago in reply to Jiaxin Teng

Expert 1030 points

Thanks for the confirmation

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TMDXIDDK379D: fcl_f2837x_tmdxiddk pwm update confusion