Hello friends, I am trying to get UART1 output from STM32F767 using Keil, There is no output showing in the Serial monitor. I am adding my code with this Please help me out

[JS.13]

Details

STM32F767Zi

Keil

HSI =16Mhz

PLL=72 Mhz

UART1

PLL source = HSI

APB2 = 72Mhz

Baudrate = 9600;

/*

void _PLL()

{

//RCC->CR|=1<<24;

RCC->PLLCFGR&=0;

RCC->PLLCFGR|=(2<<28)|(6<<24)|(216<<6)|(1<<3)|(1<<17);

FLASH->ACR&=0;

FLASH->ACR|=1<<11|1<<9|1<<8|1<<1|1<<0;

RCC->CFGR|=4<<10|1<<1;//

RCC->CIR|=1<<12;

RCC->CIR|=1<<20;

RCC->CR|=1<<24;

//while(((RCC->CIR)&1<<4)==0);

//RCC->CIR|=1<<20;

// GPIOA->BSRR=(1<<5);

}

void uart1_init()

{

RCC->AHB1ENR|=1<<1;

RCC->APB2ENR|=1<<4 | 1<<14; // UART1 clock enable

//RCC->APB2LPENR|=1<<4 | 1<<14;

RCC->DCKCFGR2|=1<<0; 

GPIOB->MODER|=(1<<29)|(1<<31); // PB15 and PB14 are set for ALTERNATE FUNTION

GPIOB->AFR[0]=1<<18; // AZlternate function for Transmission

GPIOB->OSPEEDR|=1<<28|1<<29; // Set High speeed

USART1->BRR&=0;

USART1->BRR|= ((72000000)/9600);   // Baud rate for 9600 0X57E4;  //

USART1->GTPR&=0;

//RCC->CFGR&=0;

USART1->CR1&=0;

USART1->CR1|=1<<0|1<<7|1<<6;//|1<<1;  //UART Enabled (UE)

//USART1->CR1|=1<<3;  // Transmission Enabled (TE)

}

void main()

{

_PLL();

uart1_init();

while(!((USART1->ISR)&(1<<7))); // Checking the flag setting TXE

USART1->TDR='A'; // Data to be transmitted

while(!((USART1->ISR)&(1<<6)));

delay(5);

}

*/

[Tesla DeLorean]

Looks like hours of fun..

I don't think PB14/PB15 are going to be covered by AFR[0]

AFR[1] &= 0x00FFFFFF;

AFR[1] |= 0x44000000;

I would suggest first get the USART outputting from the HSI clock source, then move the the PLL

[JS.13]

Thanks for your suggestion.

the manual says for UARTTx, Alternate function is 4 , AF4, Since AF4 is in AFR[0] ,( I think so, Sorry if I am wrong)

I tried with HSI also but there is no proper output

[JS.13]

Please Help me friends

[JS.13]

@Community member​ 

Hello Clive, I already done it with HSI. But there is no output, If you don't mind could you guide me to resolve the issue

[Tesla DeLorean]

[Tesla DeLorean · Accepted solution]

>>If you don't mind could you guide me to resolve the issue

When you go free climbing you don't expect people to run ropes for you. Consider more normative programing styles.

Remember the USART output at CMOS Levels, not RS232 Levels

//****************************************************************************
 
void usart1_init(void) // USART1 PB14/PB15
{
  RCC->AHB1ENR |= 1<<1; // GPIOB
  RCC->APB2ENR |= 1<<4; // USART1
 
  GPIOB->MODER = (GPIOB->MODER & 0x0FFFFFFF) | 0xA0000000; // PB15/PB14 AF
  GPIOB->OSPEEDR = (GPIOB->OSPEEDR & 0x0FFFFFFF); // PB15/PB14 9.6KHZ BELOW 2MHZ
  GPIOB->OTYPER = (GPIOB->OTYPER & 0x3FFF); // PB15/PB14 OUTPUT-PP AF OVERRIDES
  GPIOB->PUPDR = (GPIOB->PUPDR & 0x0FFFFFFF); // PB15/PB14 NO PULL
  GPIOB->AFR[1] = (GPIOB->AFR[1] & 0x00FFFFFF) | 0x44000000; // PB15/PB14 AF4
 
  USART1->CR1 = (1 << 3) | (1 << 2);  // TE RE
  USART1->BRR = ((16000000)/9600);   // Baud rate for 9600 from HSI
  USART1->CR2 = 0;
  USART1->CR3 = 0;
  USART1->GTPR = 0;
  USART1->CR1 |= (1 << 0); // UE
}
 
 
void usart1_outchar(char c)
{
  while((USART1->ISR & (1<<7)) == 0);
  USART1->TDR = c;
}
 
void usart1_outstring(char *s)
{
  while(*s)
    usart1_outchar(*s++);
}
 
void usart1_test(void)
{
  usart1_init();
  usart1_outstring("Hello World!\r\n");
}
 
//****************************************************************************
 
void usart3_init(void) // USART3 PD8/PD9 - NUCLEO-144
{
  RCC->AHB1ENR |= 1<<3; // GPIOD
  RCC->APB1ENR |= 1<<18; // USART3
 
  GPIOD->MODER = (GPIOD->MODER & 0xFFF0FFFF) | 0x000A0000; // PD9/PD8 AF
  GPIOD->OSPEEDR = (GPIOD->OSPEEDR & 0xFFF0FFFF); // PD9/PD8 9.6KHZ BELOW 2MHZ
  GPIOD->OTYPER = (GPIOD->OTYPER & 0xFFCF); // PD9/PD8 OUTPUT-PP AF OVERRIDES
  GPIOD->PUPDR = (GPIOD->PUPDR & 0xFFF0FFFF); // PD9/PD8 NO PULL
  GPIOD->AFR[1] = (GPIOD->AFR[1] & 0xFFFFFF00) | 0x00000077; // PD9/PB8 AF7
 
  USART3->CR1 = (1 << 3) | (1 << 2);  // TE RE
  USART3->BRR = ((16000000)/9600);   // Baud rate for 9600 from HSI
  USART3->CR2 = 0;
  USART3->CR3 = 0;
  USART3->GTPR = 0;
  USART3->CR1 |= (1 << 0); // UE
}
 
 
void usart3_outchar(char c)
{
  while((USART3->ISR & (1<<7)) == 0);
  USART3->TDR = c;
}
 
void usart3_outstring(char *s)
{
  while(*s)
    usart3_outchar(*s++);
}
 
void usart3_test(void)
{
  usart3_init();
  usart3_outstring("Hello World!\r\n");
}
 
//****************************************************************************

[T J]

Hi, in you code, you dont have a loop.

if it is working you will only get one byte.

void main()

{

_PLL();

uart1_init();

while(1){

while(!((USART1->ISR)&(1<<7))); // Checking the flag setting TXE

USART1->TDR='A'; // Data to be transmitted

while(!((USART1->ISR)&(1<<6)));

delay(5);

}

}

[JS.13]

@Community member​  . Thanks for your valuable time