STM32F407 Uart Byte Received error(higher4bit)

[jhl14]

Hi,

Using "STM32F4xx_DSP_StdPeriph_Lib_V1.8.0" to config STM32F407 Uart1 as following

///////////////////////////////////////////////////////////////////////////

void USART1_Init(u32 baudrate)

{

USART_InitTypeDef USART_InitStructure;

GPIO_InitTypeDef GPIO_InitStructure;

/* Step 1 enable the clock of USART1 and GPIO */

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

 GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;

 GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; 

GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

 GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;

 GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; 

GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1);

USART_InitStructure.USART_BaudRate = baudrate;

USART_InitStructure.USART_WordLength = USART_WordLength_8b;

USART_InitStructure.USART_StopBits = USART_StopBits_1;

USART_InitStructure.USART_Parity = USART_Parity_No;

USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

USART_Init(USART1, &USART_InitStructure);

USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);

USART_ClearITPendingBit(USART1,USART_IT_CTS|USART_IT_LBD|USART_IT_TC|USART_IT_RXNE);

USART_Cmd(USART1, ENABLE);

USART_ClearFlag(USART1, USART_FLAG_TC);

}

////////////////////////////////////////////////////////////////////////////////

At the Pin RX of STM32F407 , capture the correct data written down by the host as following chart show

But got the following bytes content in the Rxbuffer

​

even in the memory location, the data in the DR reg is 0xC8 for the 3rd byte received, not 0xA8 shown at the pin's wave.

​

Thank you for any thoughts!

BRs,

JH​

[jhl14 · Accepted solution]

This LOW LEVEL error is resolved by changing the HSE_VALUE to 8000000HZ。

 #if !defined (HSE_VALUE) 

 #define HSE_VALUE  ((uint32_t)8000000) /*!< Value of the External oscillator in Hz(25000000 default value) */

 #endif /* HSE_VALUE */