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 11, 2017 at 16:50

Can we *PLEASE* keep all your USART related adventures in one thread? Your audience here is limited.

You would need to make sure HSE_VALUE is correctly defined for the board, perhaps in stm32f4xx_conf.h and be 8000000 and not 25000000. Check also that system_stm32f4xx.c configures the PLL with the expectation of an 8 MHz crystal and not a 25 MHz one.

Unless you change the bus speeds dynamically you shouldn't need to revisit USART->BRR

Send an 0x55 data pattern and confirm the bit timing with a scope. Don't send data to the register unless TXE is asserted, you'll just garble things.

[Carter Lee]

Posted on September 12, 2017 at 16:16

Clive, I'm struggling to receive data from PC with code below.

Sending data from STM32 board to PC is working good.

But receiving from PC has a problem.

The below image ,  I just prove the PA10 while sending data.

I'm not sure but would you please check this configuration?

void SendCharUSART1(char ch){

// Wait until TXE is setwhile(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET){}USART_SendData(USART1, ch);// Wait until the end of transmitwhile(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET){}}char GetCharUSART1(void){ char ch; // Wait until the USART1 Receive Data Register is not emptywhile(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET){}ch = (USART_ReceiveData(USART1) & 0xFF);return ch; } 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); 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);

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

SYSCFG_EXTILineConfig(0x0,0);

...

SendCharUSART1(0x0D);

SendCharUSART1(0x0A);SendCharUSART1('U');SendCharUSART1('S');SendCharUSART1('A');SendCharUSART1('R');SendCharUSART1('T');SendCharUSART1('1');SendCharUSART1('>');// Get and echo USART1ch = GetCharUSART1();while (ch != 0x0D) {SendCharUSART1(ch);ch = GetCharUSART1();}

What am I missing?

Currently, stuck in here  while(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET)  

during sending the data from PC to eval board.

[Tesla DeLorean]

Posted on September 12, 2017 at 16:31

So you show me a static signal on the USART1_RX and ask why it receives nothing?

Is this pin clashing with the VCP? Did you disconnect the ST-LINK's USART from the STM32F429? Make sure SB15 is *REMOVED*

[Tesla DeLorean · Accepted solution]

Posted on September 12, 2017 at 16:34

See here, where you were told about removing SB15

https://community.st.com/0D50X00009XkXNtSAN

[Carter Lee]

Posted on September 12, 2017 at 16:49

Can check once again please ?

I prove the each pins PA10 and PA9 to PA2 and PA3.

 

Then I found PA10 is connected with JP4's TX and PA9 is connected with JP4's RX not PA2 and PA3.

I can't find their connection between PA10 and PA2  also  PA9 and PA3.

[Tesla DeLorean]

Posted on September 12, 2017 at 17:01

>>Can check once again please ?

What am I checking? Are you using the ST-LINK's VCP for these tests, or your external serial dongle from you prior thread?

What exactly have you go wired to what?

A scope trace with a flat-line is not going to result in data reception, if you are sending data why can you not see it?

[Carter Lee]

Posted on September 12, 2017 at 17:07

Isn't USART1 connected to the VCP on the DISC1 board? via PA9 and PA10.

As you said, I think I have to look for another free pins for using UART.

BTW If I remove SB15, is there any serious problem?

I think it's connecting with 'uart bootloader'.

[Carter Lee]

Posted on September 12, 2017 at 17:14

No, I'm not using uart pin for uploading firmware. I just connect to mini USB cable.

As you can see the scope trace, I think something work as a barrier to prevent received data from external serial dongle

[Carter Lee]

Posted on September 12, 2017 at 17:42

Hi Clive,

Can I use uart port as a pair such as 

PD5 USART2_TX, PC11 USART3_RX or should I have to make sure the pair such as UART3_TX and UART3_RX?

 I separately implemented  

PD5 USART2_TX, PC11 USART3_RX but it's working.good.

void SendCharUSART1(char ch){// Wait until TXE is setwhile(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET){}USART_SendData(USART1, ch);// Wait until the end of transmitwhile(USART_GetFlagStatus(USART2, USART_FLAG_TC) == RESET){}}char GetCharUSART1(void){ char ch; // Wait until the USART1 Receive Data Register is not emptywhile(USART_GetFlagStatus(USART3, USART_FLAG_RXNE) == RESET){}ch = (USART_ReceiveData(USART3) & 0xFF);return ch; }

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_15 | GPIO_Pin_11;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_Init(GPIOG, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_Init(GPIOG, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; 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(GPIOD, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11; 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(GPIOC, &GPIO_InitStructure); GPIO_PinAFConfig(GPIOD, GPIO_PinSource5, GPIO_AF_USART2); // USART1_TX GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_USART3); // 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_Init(USART3, &USART_InitStructure); USART_Cmd(USART3, ENABLE); 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_Tx; USART_Init(USART2, &USART_InitStructure); USART_Cmd(USART2, ENABLE);

SendCharUSART1(0x0D);

SendCharUSART1(0x0A);SendCharUSART1('U');SendCharUSART1('S');SendCharUSART1('A');SendCharUSART1('R');SendCharUSART1('T');SendCharUSART1('1');SendCharUSART1('>');// Get and echo USART1ch = GetCharUSART1();while (ch != 0x0D) {SendCharUSART1(ch);ch = GetCharUSART1();}