To update DMA (array buffer) during runtime for changing duty cycle of TIMER 1 pwm complementary channels on STM32F103C8T6(bluePill).

[HJang.3]

My question is regarding HAL library in STM32F103C8T6(blue Pill) , I've just started using stm32 , I've good knowledge about arduino.

I am trying to make sine PWM for a single phase inverter. For that i need channel1 of timer1 to generate complementary pwm signal Which i ve done using DMA (array of duty cycles), to vary duty cycle.

I've used :

 HAL_TIM_PWM_Start_DMA(&htim1, TIM_CHANNEL_1, (uint32_t *) sinebuffer, 60);

 HAL_TIMEx_PWMN_Start(&htim1, TIM_CHANNEL_1);

to generate PWM.

but this circular DMA buffer contains values to generate 100% sine amplitude only.(max duty cycle).

So to implement feedback to the project , I have to update DMA array Values (into some percentage of initial values)

Now i don't know how to implement it,

if there is a way like for example CCR = ( array[x] * percentage)

or any other method to multiple DMA array values (1 to 100%).

I will read percentage from analog pin.

THANK YOU

[waclawek.jan]

Period of PWM output is given by value of TIMx_ARR, while pulse duration is given by TIMx_CCRx.

Thus, duty = (TIMx_CCRx + 1) / (TIMx_ARR + 1).

Reverse it to calculate TIMx_CCRx from TIMx_ARR and duty.

JW

[HJang.3]

I can calculate CCR values, as I already have DMA array buffer of CCR values for different duty cycle. Now i want to update that DMA array values while the program is running .

How can i do that ?

THANKS.

[waclawek.jan · Accepted solution]

Usually, you use DMA array twice as big. In the Half Transfer interrupt you can update the first half, in the Transfer Complete interrupt the second half.

JW

[HJang.3]

Thanks man.

Will try to implement it.