PWM dimming, from high duty cycle to low duty cycle(80%---50%), the human eye feels that the light will flash a few times

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PWM dimming, from high duty cycle to low duty cycle(80%---50%), the human eye feels that the light will flash a few times

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yuboli
Contributor II

PWM dimming, from high duty cycle to low duty cycle(80%---50%), the human eye feels that the light will flash a few times

My pwm dimming program is

vAHI_TimerEnable(E_AHI_TIMER_1, 2, FALSE, FALSE, TRUE);

vAHI_TimerConfigureOutputs(E_AHI_TIMER_1, TRUE, TRUE); /* Invert PWM and disable gating */
vAHI_TimerClockSelect(E_AHI_TIMER_1, FALSE, TRUE);

vAHI_TimerStartRepeat(E_AHI_TIMER_1,Level_Value,4000000/477);

When I change the Level_Value value, the duty cycle will change.But the light flash a few times

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FelipeGarcia
NXP Employee
NXP Employee

Hi Daniel,

 

Could you please tell me which board are you working on?

 

Also, I'd like you to explain in detail your issue so I can replicate it and give you a better support.

 

Best regards,

Felipe

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yuboli
Contributor II

hi Felipe Garcia,

I use the JN-AN-1218-Zigbee-3-0-Light-Bulb project, compile options select DimmableLight, GpProxy, JN5169, DR1175.But the process of adjusting the duty cycle, the bulb will flash a few times;The duty cycle is correct, but I don’t know why.

My pwm dimming program is

vAHI_TimerEnable(E_AHI_TIMER_1, 2, FALSE, FALSE, TRUE);

vAHI_TimerConfigureOutputs(E_AHI_TIMER_1, TRUE, TRUE); /* Invert PWM and disable gating */
vAHI_TimerClockSelect(E_AHI_TIMER_1, FALSE, TRUE);

vAHI_TimerStartRepeat(E_AHI_TIMER_1,Level_Value,4000000/477);

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FelipeGarcia
NXP Employee
NXP Employee

Hi Daniel,

 

Sorry for my late reply.

 

Could you please try adding a delay before StartRepeat?

 

Also, could you please provide the DIO pin you are using?

 

Regards,

Felipe

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yuboli
Contributor II

hi  Felipe Garcia

   I adjust the duty cycle process, there is a time gradual process, the time is about 3s; why does it look like a few times when the brightness is low? My minimum gradient is 1;pastedImage_1.png

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FelipeGarcia
NXP Employee
NXP Employee

Hi Daniel,

 

I tested this on my side and I couldn’t see this behavior. I changed the duty cycle from around 50 to 90% and the LED didn’t blink.

 

From what I understand, when you change the duty cycle, the LED blinks a few times before the duty cycle is updated. The PWM is working fine but there are some flashes at the beginning of the process.

 

Am I correct?

 

Best regards,

Felipe

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