How do I configure GPIO pin (PE8 )as PWM output to control LED Brightness.

[AQuad.2]

I am a newbie and trying to make my hands dirty in STM32l476 Discovery board.

I am trying to control the brightness of an LED which is connected onboard at GPIO PIN PE8.

The TIMER on this pin is TIM1 CH1N.

What I have tried is till now is below. I would request someone to please go through and correct where I am wrong.

STEP1: Setting the GPIO PIN PE8 to TIM1CH1N functionality.

STEP2: Clock Configuration is set to 40MHz.

STEP3: TIMER mode and configurations as below.

Clock Source - Internal Clock Source.

Channel 1 - PWM GENERATION CH1N

STEP4: Counter Settings as below.

Prescaler Value - 40000 (To make clock as 1000 Hz)

Counter Period (ARR) - 100 -1 (Max limit in one second)

Now in programming part.

I am starting the timer with the by calling below API.

HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1);

Now in the while loop i wanted to change brightness of an LED.

while(1)

{

htim1.Instance-> CCR1 = 50; // For 50% brightness on PE8 LED//

HAL_Dealy(1000);

htim1.Instance->CCR1 = 100; // FOR 100% brightness on PE8 LED//

HAL_Dealy(1000);

}

I would once again request someone to guide me and let me understand this topic with detailed explanation.

Thanks in Advance! and Looking forward to hear from someone.

[Javier1]

why TIM1CH1N ?

the N means its going to be the exact oposite of TIM1CH1

so CCR=100 would be pwm=0%;

also try TIM1->CCR1=50 instead of htim1.instance

[waclawek.jan]

> HAL_TIM_PWM_Start()

That does not enable the TIM1_CH1N, only TIM1_CH1. You have to use HAL_TIMEx_OCN_Start().

> let me understand this topic with detailed explanation.

If you want to understand what you are doing, read the Reference Manual. Cube/HAL is open source, you can look at what the different functions do. Or just simply don't use Cube/HAL and write programs by directly accessing the mcu registers.

> the N means its going to be the exact oposite of TIM1CH1

Only if TIM1_CH1 is enabled.

JW