Hi,
I am learning how to use LPUART1 on the Nucleo-64 (STM32L433RCT6P) to generate messages on the COM4 port of my Windows 10 laptop. A "Hello World\r\n" message should be printed every time the blue User Button on the board gets pressed.
Here are the relevant variables used:
UART_HandleTypeDef hlpuart1;
/* Buffer used for transmission */
uint8_t aTxBuffer[13] = "Hello World\r\n";
/* Flag for push button */
__IO FlagStatus xPush = RESET;The LPUART1 Initialization:
static void MX_LPUART1_UART_Init(void)
{
/* USER CODE BEGIN LPUART1_Init 0 */
/* USER CODE END LPUART1_Init 0 */
/* USER CODE BEGIN LPUART1_Init 1 */
/* USER CODE END LPUART1_Init 1 */
hlpuart1.Instance = LPUART1;
hlpuart1.Init.BaudRate = 9600;
hlpuart1.Init.WordLength = UART_WORDLENGTH_8B;
hlpuart1.Init.StopBits = UART_STOPBITS_1;
hlpuart1.Init.Parity = UART_PARITY_NONE;
hlpuart1.Init.Mode = UART_MODE_TX_RX;
hlpuart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
hlpuart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
hlpuart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
if (HAL_UART_Init(&hlpuart1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN LPUART1_Init 2 */
/* USER CODE END LPUART1_Init 2 */
}The main code:
int main(void)
{
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* Configure the system clock */
SystemClock_Config();
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_LPUART1_UART_Init();
/* Infinite loop */
while (1)
{
/* xPush is a variable that is SET inside a GPIO IRQ Handler */
if(xPush == SET)
{
if(HAL_UART_Transmit(&hlpuart1, (uint8_t*)aTxBuffer, 13, 5000)!= HAL_OK)
{
Error_Handler();
}
HAL_Delay(100);
xPush = RESET;
}
}
}Here is the clock initialization (I am using HSI16 as the system clock, and the PCLK1 powers the LPUART1):
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
RCC_OscInitStruct.LSIState = RCC_LSI_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4; // LPUART1
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV8; // USART1
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
{
Error_Handler();
}
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1|RCC_PERIPHCLK_LPTIM1|RCC_PERIPHCLK_LPUART1;
PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK2;
PeriphClkInit.Lptim1ClockSelection = RCC_LPTIM1CLKSOURCE_LSI;
PeriphClkInit.Lpuart1ClockSelection = RCC_LPUART1CLKSOURCE_PCLK1;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
{
Error_Handler();
}
/** Configure the main internal regulator output voltage
*/
if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
{
Error_Handler();
}
}And this is what I am seeing in the PuTTY Terminal with one button press:
I believe this is caused by a mismatch in the baud rate, even though the LPUART1's baud rate configuration is 9600 and the PuTTY's baud rate configuration is 9600. I also matched and verified that all the parameters are the same: 8 Data bits (in PuTTY) where LPUART1 has wordlength 8 bits (including parity, although parity is 0), 1 stop bits on both PuTTY and LPUART1, no parity on both, and no flow control on both. Here is the PuTTY configuration:
I have also read the user manual here and confirmed that LPUART1 has a connection with the ST-LINK, and that SB66 and SB75 is soldered. Regarding the pins that I am using, I am using PA2 as LPUART1_TX and PA3 as LPUART1_RX, both configured to Alternate Function 8 (LPUART1) with no pull-up or pull-down resistors.
What could be the issue here? I tried varying the baud rate on PuTTY to initially make sure that the amount of characters I receive and I am sending are the same based on a suggestion here. I also tried increasing the APB1 clock peripheral's divider (PCLK1 clocks the LPUART1 here). Would using HSI also be fine in this application?
Any help would be appreciated. Thanks!
