The serial port assistant sends PWM light source commands, but the light source displays strangely?

xbxdbd

The serial port assistant sends PWM light source commands, but the light source displays strangely? [Copy link]

I use the serial assistant to send a command to light up the PWM light source with a frequency of 20Khz. When I send the command, the brightness changes from 0-6. From 7 to 99, the brightness remains the same. Then when I send 100, the brightness becomes lower. What is the reason for this?

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
	uint8_t ucTemp;

	if(huart ->Instance == USART1)
    {
				ucTemp = aRxBuffer;
				Uart1_RxBuff[Uart1_Rx_Cnt++] = ucTemp;
				if(Uart1_RxBuff[0]!=0xa3)
					Uart1_Rx_Cnt=0;
				if((Uart1_Rx_Cnt==2) && (Uart1_RxBuff[1]!=0xb3))
					Uart1_Rx_Cnt=0;
				if(Uart1_Rx_Cnt==8)
				{
					if(data_test(Uart1_RxBuff))
					{

						/********************
						üDêyY
						*********************/
						
						turn = Uart1_RxBuff[2];
						pwm = Uart1_RxBuff[3];

						
						
						if(turn == 0)
						{
								pwm_light(0);
						}
						else if(turn == 1)
						{
								pwm_light( pwm);
						}
	
					}
					Uart1_Rx_Cnt = 0;
				}
				
				HAL_UART_Receive_IT(&huart1,&aRxBuffer,1);
    }
}
void  pwm_light(uint8_t pwm)
{

   __HAL_TIM_SetCompare(&htim2,TIM_CHANNEL_1, pwm);

}

秦天qintian0303

This depends on whether the duty cycle and brightness control are linear. There are many such examples. Test it with a fixed duty cycle.

yangjiaxu

There may be a problem with the duty cycle setting of the PWM controller, resulting in no change in the duty cycle at certain brightness values; or there may be a problem with the logic of the control software, resulting in the inability to correctly control the PWM output at certain brightness values

xbxdbd

yangjiaxu posted on 2024-9-11 12:03 There may be a problem with the duty cycle setting of the PWM controller, resulting in no change in the duty cycle at certain brightness values; or there may be a problem with the logic of the control software...

The entire receiving serial port logic is only this, and the light source processing logic is PWM_light: __HAL_TIM_SetCompare(&htim2,TIM_CHANNEL_1, pwm);