No uart activity stm32f105

Posted on June 30, 2014 at 15:37

I'm not sure there are many using it in that fashion, so you're likely going to need to go through the PLL2 settings/configurations yourself.

STM32F10x_StdPeriph_Lib_V3.5.0\Libraries\CMSIS\CM3\DeviceSupport\ST\STM32F10x\system_stm32f10x.c

TM32F105_107_AN3354_FW_V1.0.0\Project\STM32F105_107_IAP_USBHost\src\system_stm32f10x.c

I'd suppose I could get 40 MHz (25 / 5 * 8) from the example by using (8 / 2 * 10) or (8 / 4 * 20), or you could use HSE directly, and not use PREDIV1

And ensure HSE_VALUE is 8000000

Posted on July 01, 2014 at 12:58

Thanks Clive

I tried (8 / 2 * 10)  to get 40 Mhz

PREDIV2 =  /2

PLL2MUL = x10

and then used

PREDIV1 = /5

PLLMUL =x6

HSE_VALUE is 8000000

I've changed the following code in system32f10x.c. Do I need to modify any other code?

Cheers

Bob

static void SetSysClockTo48(void)

{

  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;

 

  /* SYSCLK, HCLK, PCLK2 and PCLK1 configuration ---------------------------*/   

  /* Enable HSE */   

  RCC->CR |= ((uint32_t)RCC_CR_HSEON);

 

  /* Wait till HSE is ready and if Time out is reached exit */

  do

  {

    HSEStatus = RCC->CR & RCC_CR_HSERDY;

    StartUpCounter++; 

  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CR & RCC_CR_HSERDY) != RESET)

  {

    HSEStatus = (uint32_t)0x01;

  }

  else

  {

    HSEStatus = (uint32_t)0x00;

  } 

  if (HSEStatus == (uint32_t)0x01)

  {

    /* Enable Prefetch Buffer */

    FLASH->ACR |= FLASH_ACR_PRFTBE;

    /* Flash 1 wait state */

    FLASH->ACR &= (uint32_t)((uint32_t)~FLASH_ACR_LATENCY);

    FLASH->ACR |= (uint32_t)FLASH_ACR_LATENCY_1;   

 

    /* HCLK = SYSCLK */

    RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;

     

    /* PCLK2 = HCLK */

    RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE2_DIV1;

   

    /* PCLK1 = HCLK */

    RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV2;

   

#ifdef STM32F10X_CL

    /* Configure PLLs ------------------------------------------------------*/

    /* PLL2 configuration: PLL2CLK = (HSE / 2) * 10 = 40 MHz */

    /* PREDIV1 configuration: PREDIV1CLK = PLL2 / 5 = 8 MHz */

 

       

    RCC->CFGR2 &= (uint32_t)~(RCC_CFGR2_PREDIV2 | RCC_CFGR2_PLL2MUL |

                              RCC_CFGR2_PREDIV1 | RCC_CFGR2_PREDIV1SRC);

    RCC->CFGR2 |= (uint32_t)(RCC_CFGR2_PREDIV2_DIV2 | RCC_CFGR2_PLL2MUL10 |

                             RCC_CFGR2_PREDIV1SRC_PLL2 | RCC_CFGR2_PREDIV1_DIV5);

 

    /* Enable PLL2 */

    RCC->CR |= RCC_CR_PLL2ON;

    /* Wait till PLL2 is ready */

    while((RCC->CR & RCC_CR_PLL2RDY) == 0)

    {

    }

   

  

    /* PLL configuration: PLLCLK = PREDIV1 * 6 = 48 MHz */

    RCC->CFGR &= (uint32_t)~(RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLSRC | RCC_CFGR_PLLMULL);

    RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLXTPRE_PREDIV1 | RCC_CFGR_PLLSRC_PREDIV1 |

                            RCC_CFGR_PLLMULL6);

#else   

    /*  PLL configuration: PLLCLK = HSE * 6 = 48 MHz */

    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMULL));

    RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_HSE | RCC_CFGR_PLLMULL6);

#endif /* STM32F10X_CL */

    /* Enable PLL */

    RCC->CR |= RCC_CR_PLLON;

    /* Wait till PLL is ready */

    while((RCC->CR & RCC_CR_PLLRDY) == 0)

    {

    }

    /* Select PLL as system clock source */

    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));

    RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;   

    /* Wait till PLL is used as system clock source */

    while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)0x08)

    {

    }

  }

  else

  { /* If HSE fails to start-up, the application will have wrong clock

         configuration. User can add here some code to deal with this error */

  }

}

 

Posted on July 02, 2014 at 01:13

Hi Clive,

I checked the various clock registers and they look to be fine. The USART1 looks ok too. However on stepping through the code, it hangs at the printf function. It occasionally outputs one rubbish character and then sits there. The retarget is pretty simple and is the same as was working on a f051 part.

Bob

PUTCHAR_PROTOTYPE

{

  /* Place your implementation of fputc here */

  /* e.g. write a character to the USART */

  USART_SendData(USART1, (uint8_t) ch);

          

  /* Loop until the end of transmission */

 while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET)      

  {}

  return ch;

}

Posted on July 02, 2014 at 02:28

I'd prefer to front test TXE, than wait on TC at the back. TC is prone to interference from the debugger sat viewing the peripheral. I guess TC has the benefit that the character reaches the terminal before following code crashes (though the machine keeps ticking in the background, might be important to wait for the USART to flush in power down or low power transitions, or changing baud rate or internal clocks)

PUTCHAR_PROTOTYPE
{
/* Place your implementation of fputc here */
while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET); 
/* e.g. write a character to the USART */
USART_SendData(USART1, (uint8_t) ch);
return(ch);
}

Posted on July 02, 2014 at 08:34

Cheers Clive,

I'll give this a go this evening and report back. I have a feeling it is going to be something more fundamental though.

Bob

Posted on July 02, 2014 at 23:17

Hi Clive,

It didn't work I'm afraid. I think there is something very fundamental going wrong here. I don't think the system is being configured properly on startup. The SysTick_Handler function isn't being called and this leads me to suspect that other interrupts say for controlling the uart aren't functioning. I can step through the code at the start of main() switching on LEDs, but it hangs at Delay(1000);

I have a delay before I print out using the usart and I can't even get a delay using this SysTick_Handler. The reason I know it isn't being called is that I switch on an LED in this function. It never happens. Any basic setup checks that I can perform to help see what is happening?

Many Thanks

Bob

Posted on July 03, 2014 at 02:45

I suspect you probably want to go about printf() in Keil differently. I tend to use the semi-hosting route. Other ways might well end up hard faulting on an SWI instruction.

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Posted on July 04, 2014 at 23:45

Hi Clive,

I think our problem revolves around us having an incorrect crystal on the board. The CL series expects 25 MHz and we have an 8 MHz crystal on board. Changing the PLL multipliers and dividers doesn't really help we we are going to have to change the crystal.

One thing that bothers me is that SysTick isn't working. I always believed that it was running on startup and all I had to do was configure the tick rate. This was the way on the previous micro. On the STM32F105 do I have to enable the SysTick interrupt on is it done by default?

Many Thanks

Bob

Posted on July 05, 2014 at 00:28

The SysTick configuration enables and sets the rate, there are other things to set the priority, and it's a system handler, rather than an interrupt per se.

You should be able to route clocks via the MCO pin (PA8) to confirm they are working.

The original F10x design had some pretty restrictive PLL options, so really needed 8 or 4 MHz sources to work. you could get to 48 MHz via a 1.5 division of 72 MHz, and this magic occurs because the VCO clocks at twice the rate used, because it doesn't have the right duty cycle.

There's no good way to get 25 MHz, and Ethernet needs that or 50 MHz, so you could get away with one clock source. If you don't have Ethernet, or your PHY has it's own clock, I don't see why the chip couldn't be used with an 8 MHz source. The F107 I have uses a 25 MHz, you'd have to send me a board with 8 MHZ if you wanted me to experiment.

Posted on July 07, 2014 at 09:49

Hi Clive,

In order to get the uart working,  I had to remove the SysClock_Config line. If I leave this line inserted, the usart will hang after printing 10 characters. However I need SysClock running in order to generate a delay. The Vector table contains the proper SysTick_Handler address. 

The clocks are up and stable at 48 MHz. I can see then on MCO pin.

Any ideas Clive why no delay occurs or why it kills the usart? Is it an exception that I'm not handlind or is SysTick even confugured properly?

Thanks

Bob

int main(void)

{

RCC_ClocksTypeDef RCC_Clocks;

// Enable SYSCFG clock

SetSysClockTo48() ;

/* SysTick end of count event each 1ms */

RCC_GetClocksFreq(&RCC_Clocks);

/* SysTick_Config(RCC_Clocks.HCLK_Frequency / 1000);  */ USART works when commented */

/* Switch ON all clocks to the ports */

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

Usart1Init(); // Console

/*Delay(1000); *     /*Code will hang at this line if SysTick Enabled */

 

printf(''\n\rHello World\n\r'');

}

The SysTick handler is as per supplied example.

/**

  * @brief  This function handles SysTick Handler.

  * @param  None

  * @retval None

  */

void SysTick_Handler(void)

{

  TimingDelay_Decrement();

}

/**

  * @brief  Inserts a delay time.

  * @param  nTime: specifies the delay time length, in milliseconds.

  * @retval None

  */

void Delay(__IO uint32_t nTime)

{

  TimingDelay = nTime;

  while(TimingDelay != 0);

}

/**

  * @brief  Decrements the TimingDelay variable.

  * @param  None

  * @retval None

  */

void TimingDelay_Decrement(void)

{

  if (TimingDelay != 0x00)

  {

    TimingDelay--;

  }

}