Posted on August 20, 2016 at 18:05
Hello,
I have a problem with PLL from HSI on STM32F401 (on Nucleo Board). I am not able to run PLL, if I read actual clock, it is always 16 MHz.
The code without PLL set gives me always
System clock: 16 MHz, HCLK: 16 MHz, PCLK1: 16 MHz, PCLK2: 16 MHz
If I put PLL settings (as written bellow) USART output does not work at all or have a wrong baudrate.
Can you help me what is wrong?
Thank you
int
main(
void
)
{
RCC_ClocksTypeDef clocks;
RCC_DeInit();
RCC_HSICmd(ENABLE);
RCC_HCLKConfig(RCC_SYSCLK_Div1);
/* HCLK = SYSCLK */
RCC_PCLK1Config(RCC_HCLK_Div2);
/* PCLK1 = HCLK*/
RCC_PCLK2Config(RCC_HCLK_Div1);
/* PCLK2 = HCLK*/
RCC_AdjustHSICalibrationValue(0x10);
RCC_PLLConfig(RCC_PLLSource_HSI, 16, 336, 4, 7);
RCC_PLLCmd(ENABLE);
// while (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET) {}
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
SystemCoreClockUpdate();
COMInit();
RCC_GetClocksFreq(&clocks);
printf(
''\nCLOCK READ:\n\r''
);
printf(
''System clock: %u MHz, HCLK: %u MHz, PCLK1: %u MHz, PCLK2: %u MHz\n''
,
clocks.SYSCLK_Frequency/1000000, clocks.HCLK_Frequency/1000000, clocks.PCLK1_Frequency/1000000, clocks.PCLK2_Frequency/1000000);
while
(1)
{
}
}
void
COMInit(
void
)
{
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
/* Configure USART Tx as alternate function */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect PXx to USARTx_Tx*/
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
/* Configure USART Rx as alternate function */
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect PXx to USARTx_Rx*/
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);
/* USART2 Config */
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 configuration */
USART_Init(USART2, &USART_InitStructure);
/* Enable USART */
USART_Cmd(USART2, ENABLE);
}
PUTCHAR_PROTOTYPE
{
while
(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET);
// Is it empty?
USART_SendData(USART2, (uint8_t) ch);
// Ok, write it now
return
ch;
}
