STM32L4xx USB_CDC Class Configuration on SensorTile: Why Timer is needed?
Dear,
From the SensorTile Sample Code (STSW-STLKT01). The USB CDC device class is set up with some function of Timer3. I do not understand why Timer3 is used and how useful to do so. Will someone please help me to understand this?
Please refer to the code below for the setup of Timer3 on USB_CDC_Class:
static int8_t CDC_Itf_Init(void)
{
/*##-2- Enable TIM peripherals Clock #######################################*/
TIMx_CLK_ENABLE();
/*##-3- Configure the NVIC for TIMx ########################################*/
/* Set Interrupt Group Priority */
HAL_NVIC_SetPriority(TIMx_IRQn, 0x6, 0);
/* Enable the TIMx global Interrupt */
HAL_NVIC_EnableIRQ(TIMx_IRQn);
/*##-3- Configure the TIM Base generation #################################*/
TIM_Config();
/*##-4- Start the TIM Base generation in interrupt mode ####################*/
/* Start Channel1 */
if(HAL_TIM_Base_Start_IT(&TimHandle) != HAL_OK)
{
/* Starting Error */
Error_Handler();
}
/*##-5- Set Application Buffers ############################################*/
USBD_CDC_SetTxBuffer(&USBD_Device, UserTxBuffer, 0);
USBD_CDC_SetRxBuffer(&USBD_Device, UserRxBuffer);
return (USBD_OK);
}
static void TIM_Config(void)
{
/* Set TIMx instance */
TimHandle.Instance = TIMx;
/* Initialize TIM3 peripheral as follow:
+ Period = 10000 - 1
+ Prescaler = ((SystemCoreClock/2)/10000) - 1
+ ClockDivision = 0
+ Counter direction = Up
*/
TimHandle.Init.Period = (CDC_POLLING_INTERVAL*1000) - 1;
TimHandle.Init.Prescaler = 80-1;
TimHandle.Init.ClockDivision = 0;
TimHandle.Init.CounterMode = TIM_COUNTERMODE_UP;
if(HAL_TIM_Base_Init(&TimHandle) != HAL_OK)
{
/* Initialization Error */
Error_Handler();
}
}
Best,
Tony Nguyen