Question
F411 USART LL Driver Not Work Well
I have made my own PCB board with F411 MCU.
The USART2 does not work well if I use LL driver.
This is the init code generated by CubeIDE.
static void MX_USART2_UART_Init(void)
{
/* USER CODE BEGIN USART2_Init 0 */
/* USER CODE END USART2_Init 0 */
LL_USART_InitTypeDef USART_InitStruct = {0};
LL_GPIO_InitTypeDef GPIO_InitStruct = {0};
/* Peripheral clock enable */
LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_USART2);
LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);
/**USART2 GPIO Configuration
PA2 ------> USART2_TX
PA3 ------> USART2_RX
*/
GPIO_InitStruct.Pin = LL_GPIO_PIN_2|LL_GPIO_PIN_3;
GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE;
GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
GPIO_InitStruct.Alternate = LL_GPIO_AF_7;
LL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* USER CODE BEGIN USART2_Init 1 */
/* USER CODE END USART2_Init 1 */
USART_InitStruct.BaudRate = 115200;
//USART_InitStruct.BaudRate = 1000000;
USART_InitStruct.DataWidth = LL_USART_DATAWIDTH_8B;
USART_InitStruct.StopBits = LL_USART_STOPBITS_1;
USART_InitStruct.Parity = LL_USART_PARITY_NONE;
USART_InitStruct.TransferDirection = LL_USART_DIRECTION_TX_RX;
USART_InitStruct.HardwareFlowControl = LL_USART_HWCONTROL_NONE;
USART_InitStruct.OverSampling = LL_USART_OVERSAMPLING_16;
LL_USART_Init(USART2, &USART_InitStruct);
LL_USART_ConfigAsyncMode(USART2);
LL_USART_Enable(USART2);
/* USER CODE BEGIN USART2_Init 2 */
/* USER CODE END USART2_Init 2 */
}And this is the function for USART2 to transmit:
void Start_USART2_Tx(void* data, uint16_t len) {
const uint8_t* d = data;
for (; len > 0; --len, ++d) {
LL_USART_TransmitData8(USART2, *d);
while (!LL_USART_IsActiveFlag_TXE(USART2)) {}
}
while (!LL_USART_IsActiveFlag_TC(USART2)) {}
}The above code only works when baud rate is <= 115200; it hangs at
while (!LL_USART_IsActiveFlag_TXE(USART2)) {}when baud rate is higher.
However, if I use HAL library, my PCB works even baud rate reaches 921600.
static void MX_USART2_UART_Init(void)
{
/* USER CODE BEGIN USART2_Init 0 */
/* USER CODE END USART2_Init 0 */
/* USER CODE BEGIN USART2_Init 1 */
/* USER CODE END USART2_Init 1 */
huart2.Instance = USART2;
huart2.Init.BaudRate = 921600;
huart2.Init.WordLength = UART_WORDLENGTH_8B;
huart2.Init.StopBits = UART_STOPBITS_1;
huart2.Init.Parity = UART_PARITY_NONE;
huart2.Init.Mode = UART_MODE_TX_RX;
huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart2.Init.OverSampling = UART_OVERSAMPLING_16;
if (HAL_UART_Init(&huart2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART2_Init 2 */
/* USER CODE END USART2_Init 2 */
} while (1)
{
HAL_UART_Transmit(&huart2, (uint8_t *)"LED ON\r\n", 8, 0xFFFF);
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_RESET);
HAL_Delay(1000);
HAL_UART_Transmit(&huart2, (uint8_t *)"LED OFF\r\n", 9, 0xFFFF);
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
HAL_Delay(1000);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}Can any expert show me what could be the reasons?