How can I change LED's brightness with PWM and USART in USART1_IRQHandler? - stm32

Question

I am using STM32F4 discovery board and I am working on changing LED brightness and timer period using ADC and USART.
I use DMA to fetch ADC values, selected TIM4 for PWM and selected USART1 for USART. ADC, USART and PWM are working well so far, but USART1_IRQHandler() is not working as expected.
How can I adjust timer period and LED brightness with PWM and ADC in the following implementation of USART1_IRQHandler()?
void USART1_IRQHandler()
{
if (USART_GetITStatus(USART1, USART_IT_RXNE) )
{
delay(168000);
i = USART_ReceiveData(USART1);
if(i == '1'){
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC1Init(TIM4,&TIMOC_InitStruct);
TIM_OC1PreloadConfig(TIM4,TIM_OCPreload_Enable);
UARTSend("3 led aktif\r\n",sizeof("LED 4 ON\r\n"));
}
else if(i == '2')
{
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC1Init(TIM4,&TIMOC_InitStruct);
TIM_OC1PreloadConfig(TIM4,TIM_OCPreload_Enable);
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC2Init(TIM4,&TIMOC_InitStruct);
TIM_OC2PreloadConfig(TIM4,TIM_OCPreload_Enable);
UARTSend("2 led aktif\r\n",sizeof("LED 4 ON\r\n"));
}
else if(i == '4')
{
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC1Init(TIM4,&TIMOC_InitStruct);
TIM_OC1PreloadConfig(TIM4,TIM_OCPreload_Enable);
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC2Init(TIM4,&TIMOC_InitStruct);
TIM_OC2PreloadConfig(TIM4,TIM_OCPreload_Enable);
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC3Init(TIM4,&TIMOC_InitStruct);
TIM_OC3PreloadConfig(TIM4,TIM_OCPreload_Enable);
UARTSend("4 led aktif\r\n",sizeof("LED 4 ON\r\n"));
}
else if(i == '4')
{
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC1Init(TIM4,&TIMOC_InitStruct);
TIM_OC1PreloadConfig(TIM4,TIM_OCPreload_Enable);
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC2Init(TIM4,&TIMOC_InitStruct);
TIM_OC2PreloadConfig(TIM4,TIM_OCPreload_Enable);
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC3Init(TIM4,&TIMOC_InitStruct);
TIM_OC3PreloadConfig(TIM4,TIM_OCPreload_Enable);
TIMOC_InitStruct.TIM_Pulse=pwm_value;
TIM_OC4Init(TIM4,&TIMOC_InitStruct);
TIM_OC4PreloadConfig(TIM4,TIM_OCPreload_Enable);
UARTSend("4 led aktif\r\n",sizeof("LED 4 ON\r\n"));
}
else
{
Hello();
UARTSend("Please enter another number:\n",sizeof("Please enter another number:\n"));
}
} USART_ClearITPendingBit(USART1,USART_IT_RXNE);
}

Answer 1

About your USART1_IRQHandler, have you check if the interrupt is active with
__HAL_RCC_UART4_CLK_ENABLE();
HAL_NVIC_SetPriority(USART1_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(USART1_IRQn);
and if you enable it with this call
UART_Receive_IT( &huart1 );
I am using STM32Cube, repository V1.25.0.
Now, about your code inside the USART1_IRQHandler(), you could use shortcut to handle what you want to do. If I understand, you have 4 leds to control with the Timer4 and 4 channels.
The pulse is the Output Compare value (TIM4->CCR1 for channel 1). So, I would start the timer with a pulse equal to the Period (or zero. See note below).
From that point, if you want to change the brightness, you have just to change the pulse width with
__HAL_TIM_SET_COMPARE( htim4, TIM_CHANNEL_1, pwm_value);
or with
TIM4->CCR1 = pwm_value;
You could also disable any channel with
__HAL_TIM_DISABLE_IT( htim4, TIM_CHANNEL_1);
__HAL_TIM_ENABLE_IT( htim4, TIM_CHANNEL_1);
So, you get something like that
if(i == '1'){
TIM4->CCR1 = pwm_value;
} else if(i == '2') {
TIM4->CCR1 = pwm_value;
TIM4->CCR2 = pwm_value;
} ...
Note: I don't know how are connected your leds. If the led is connected to Vcc and the other end to the MPU pin, a LOW pulse will turn ON the led and HIGH pulse will turn it OFF.