Should USARTx->BRR have to re-calculate ?

[Carter Lee]

Posted on September 11, 2017 at 16:33

Hi,

Now I'm trying to implement UART function as the below,

But the problem is keep showing in RS232 Tool.

I'm just referring fully reference posting such as

https://community.st.com/thread/19577?commentID=48791#comment

There's no miss match. But I don't know what is the problem and how to resolve this.

Could you please any advice to resolve this problem?

I guess one thing is there's noUSARTx->BRR declaration.

Is this possible way to happen the problem??

USART_InitTypeDef USART_InitStructure;

int putcharx(int ch)

{ while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET); USART_SendData(USART1, (uint8_t)ch); return ch; } int main(void) { RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

//UART////////////////////////////////////////////////////////////////////////

/*-------------------------- GPIO Configuration ----------------------------*/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Connect USART pins to AF */

GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_USART1); // USART1_TX GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_USART1); // USART1_RX

USART_InitStructure.USART_BaudRate = 9600;

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_Cmd(USART1, ENABLE);

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

while (1) { USART_SendData(USART1, 0x49); // Send 'I' //TEST 2

}

In case TEST 1 and TEST2 have the same output result as the below image.

What am I supposed to do to resolve this problem?

should I have to calculate about

USARTx->BRR

? Note: this post was migrated and contained many threaded conversations, some content may be missing.

[Tesla DeLorean]

Posted on September 12, 2017 at 17:58

You'd have to initialize two different USART, but given the lack of available pins that is probably the best option available.

The STM32F429I-DISCO is feature rich, but the LCD+SDRAM eat a lot of available pins.

For the USART experiment I think that USART1 PA9/PA10 from the ST-LINK's VCP is a viable path to test/understand things.

If you removed solder-bridges, or zero-ohm jumpers, they can be readily replaced.

If using the VCP you can leave the bridges in place, but you should perhaps look at why you have no signal.

[Carter Lee]

Posted on September 12, 2017 at 18:25

Thanks , Your helping is very helpful., I can have a success UART polling.

I'm not sure whether I can use someday with VCP (Vitual Com Port).

Anyway. I didn't still get it about that schematic, in especially

PA10 toPA2 and PA9 to PA3, they are not connected between them. what I mean is that schematic seems something wrong.