KV4x - NanoEdge - FRACVAL1 PWM period problem

[davidelusignani]

Hi,

I am Davide Lusignani, from University of Parma (Italy).

I need to use NanoEdge function on KV4x device (MKV46F256VLL16) on all 12 PWM outputs.

The PWM period of PWMA and PWMB outputs changes when I modify FRACVAL1 register to control the duty-cycle of PWMX.

How can I disable this function and use FRACVAL1 without modifing the PWM frequency?

ps: the period of the PWM is set by EXT_SYNC from a timer.

Thanks in advance

[davidelusignani]

update?

[davidelusignani]

update?

[davidelusignani]

Someone can help me?

Thanks in advance

Davide

[xiangjun_rong]

Hi, Divide,

I am not very clear about your question.

Generally, the PWM cycle time of SM0/SM1/SM2/SM3 is controlled by the PWMA_SM0VAL1 -  PWMA_SM0INIT if you use Master Sync of SM0 to synchronize all the SM1/SM2/SM3 modules. In the case, if you enable the Fractional Delay Logic function, obviously, setting the PWMA_SM0FRACVAL1 register to non-zero value is sure to  take effect on the PWM cycle time. But if you use EXT_SYNC signal to synchronize the SM0/SM1/SM2/SM3, I think the external signal will control the PWMA cycle time.

I do not know why you use EXT_SYNC signal to synchronize all PWM sub-modules, if possible, I suggest you use Master Sync of SM0 to synchronize all the SM1/SM2/SM3 modules, and set the PWMA_SM0FRACVAL1 register to zero, in the scenario, the PWMA cycle time is only determined by PWMA_SM0VAL1 -  PWMA_SM0INIT, the disadvantage is that the PWMA_X0 signal is restricted, because PWMA_SM0VAL1 is used to control both the PWMA cycle time and falling edge of PWMA_X0 signal.

Hope it can help you

BR

XiangJun Rong

[davidelusignani]

Hi XiangJun Rong,
thanks for your answer.

I need to know if is possible to use NanoEdge function on the PWM_X without modify PWM_A and PWM_B characteristics (dutycycle, frequency, ecc).

I can use FRACVAL1 to have a fractional pwm on PWM_X, but when FRACVAL1 is a non-zero value the period of PWM_A and PWM_B changes.

I use the EXT_SYNC for set the pwm period because I do not want to use VAL0 and VAL1 registers to set it.

Davide

[xiangjun_rong]

Hi, Davide,

I suggest you clear the FRAC1_EN in PWMx_SMnFRCTRL register and have a try, I think the PWM period will not change, but I do not know if it take effect on the duty cycle of PWM_X0.

BR

Xiangjun Rong

[davidelusignani]

Hi Xiangjun Rong,

I tried to clear FRAC1_EN, but in this case the fractional edge of VAL1 is disabled, and Nanoedge function on PWM_X not work.

Davide.

[xiangjun_rong]

Hi, Davide,

I am sorry, I have not good idea to enable nano-edge function on PWM_X0 without takeing effect on the PWM period.

BR

Xiangjun rong