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Pilous Droip
Pilous Droip
Senior
January 17, 2018
Question

STM32F4Discovery and UART3 problem

  • January 17, 2018
  • 8 replies
  • 1057 views
Posted on January 17, 2018 at 13:16

Hello. I have a problem with UART3 on STM32F4Discovery kit. There is STM32F407VG. And I try send string, but program sendin wrong string. I use crystal 8MHz on HSE.

In files you can see my code.

UART: 

https://paste.ofcode.org/jqNikWZbRQvYrAsL8VnkrL

CLOCK:

https://paste.ofcode.org/3bEa2czziJ2BphWPMpjK8Ut

Main: 

https://paste.ofcode.org/GjGuUP3MK2RqXaj8KDtB9i

Any idea, what is wrong?

#stm32f4discovery #usart
This topic has been closed for replies.

8 replies

waclawek.jan
waclawek.jan
Super User
January 17, 2018
Posted on January 17, 2018 at 13:27

but program sendin wrong string

How do you know? How did you observe the output? What do you see?

JW

Pilous Droip
Pilous DroipAuthor
Senior
January 17, 2018
Posted on January 17, 2018 at 13:45

Here is my screenshots from programs (putty and hercules). In putty is more then one ''hello''. In herkules is one ''hello''.

0690X00000604GWQAY.jpg0690X00000603yjQAA.jpg
waclawek.jan
waclawek.jan
Super User
January 17, 2018
Posted on January 17, 2018 at 13:56

Set the terminals to display binary/hexadecimal, as a minimum. If these two can't do it, get Bray's and/or realterm.

Any chance to get a logic analyzer or oscilloscope and observe the lines?

Btw. what's the hardware? Are there any RS232-transceiveres?

JW

Tesla DeLorean
Tesla DeLorean
Guru
January 17, 2018
Posted on January 17, 2018 at 14:18

Enable the clock BEFORE touching pins

LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOD); // ENABLE CLOCK FIRST, SYNCHRONOUS LOGIC AHEAD

LL_GPIO_SetAFPin_8_15(GPIOD, LL_GPIO_PIN_8, LL_GPIO_AF_7);

LL_GPIO_SetAFPin_8_15(GPIOD, LL_GPIO_PIN_9, LL_GPIO_AF_7);
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Pilous Droip
Pilous DroipAuthor
Senior
January 18, 2018
Posted on January 18, 2018 at 08:01

Ok. I try change speed of UART. And I have wrong clock. I set in my UART 115200, but real speed is 38400.

I try change clock, but it isn't working:

//External CLOCK: 8MHz

void SystemClock_Config(void)

{

LL_FLASH_SetLatency(LL_FLASH_LATENCY_5);

if(LL_FLASH_GetLatency() != LL_FLASH_LATENCY_5)

{

Error_Handler();

}

LL_PWR_SetRegulVoltageScaling(LL_PWR_REGU_VOLTAGE_SCALE1);

LL_RCC_HSE_Enable();

/* Wait till HSE is ready */

while(LL_RCC_HSE_IsReady() != 1)

{

}

LL_RCC_PLL_ConfigDomain_SYS(LL_RCC_PLLSOURCE_HSE, LL_RCC_PLLM_DIV_4, 168, LL_RCC_PLLP_DIV_2);

LL_RCC_PLL_Enable();

/* Wait till PLL is ready */

while(LL_RCC_PLL_IsReady() != 1)

{

}

LL_RCC_SetAHBPrescaler(LL_RCC_SYSCLK_DIV_1);

LL_RCC_SetAPB1Prescaler(LL_RCC_APB1_DIV_4);

LL_RCC_SetAPB2Prescaler(LL_RCC_APB2_DIV_2);

LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_PLL);

/* Wait till System clock is ready */

while(LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_PLL)

{

}

LL_Init1msTick(168000000);

LL_SYSTICK_SetClkSource(LL_SYSTICK_CLKSOURCE_HCLK);

LL_SetSystemCoreClock(168000000);

}
Pilous Droip
Pilous DroipAuthor
Senior
January 18, 2018
Posted on January 18, 2018 at 08:14

Ok. Problem was with settings clock.

I use internal HSI and problem was solved.

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