Posted on June 05, 2018 at 14:21
Forking the example project, making SB14, running 4 MHz
#include <stdio.h>
#include ''stm32l4xx_hal.h''
static void SystemClock_Config(void);
//****************************************************************************
/**
* @brief Main program
* @param None
* @retval None
*/
int main(void)
{
HAL_Init();
/* Configure the System clock to have a frequency of 4 MHz */
SystemClock_Config();
printf(''
STM32L476-DISCO
'');
printf(''Core=%d, %d MHz
'', SystemCoreClock, SystemCoreClock / 1000000);
printf(''APB1=%d
'', HAL_RCC_GetPCLK1Freq());
printf(''APB2=%d
'', HAL_RCC_GetPCLK2Freq());
/* Add your application code here
*/
/* Infinite loop */
while (1)
{
}
}
//****************************************************************************
/**
* @brief System Clock Configuration
* The system Clock is configured as follows :
* System Clock source = MSI
* SYSCLK(Hz) = 4000000
* HCLK(Hz) = 4000000
* AHB Prescaler = 1
* APB1 Prescaler = 1
* APB2 Prescaler = 1
* MSI Frequency(Hz) = 4000000
* Flash Latency(WS) = 0
* @param None
* @retval None
*/
static void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
/* The following clock configuration sets the Clock configuration sets after System reset */
/* It could be avoided but it is kept to illustrate the use of HAL_RCC_OscConfig and HAL_RCC_ClockConfig */
/* and to be eventually adapted to new clock configuration */
/* MSI is enabled after System reset at 4Mhz, PLL not used */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
RCC_OscInitStruct.MSIState = RCC_MSI_ON;
RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6;
RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
/* Initialization Error */
while(1);
}
/* Select MSI as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
/* Set 0 Wait State flash latency for 4Mhz */
RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
{
/* Initialization Error */
while(1);
}
/* The voltage scaling allows optimizing the power consumption when the device is
clocked below the maximum system frequency, to update the voltage scaling value
regarding system frequency refer to product datasheet. */
/* Enable Power Control clock */
__HAL_RCC_PWR_CLK_ENABLE();
if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE2) != HAL_OK)
{
/* Initialization Error */
while(1);
}
/* Disable Power Control clock */
__HAL_RCC_PWR_CLK_DISABLE();
}
//****************************************************************************
// Hosting of stdio functionality through SWV (Make SB14)
//****************************************************************************
/* Implementation of putchar (also used by printf function to output data) */
int SendChar(int ch) /* Write character to Serial Port */
{
ITM_SendChar(ch); // From core_cm4.c
return(ch);
}
//****************************************************************************
#include <rt_misc.h>
#pragma import(__use_no_semihosting_swi)
struct __FILE { int handle; /* Add whatever you need here */ };
FILE __stdout;
FILE __stdin;
int fputc(int ch, FILE *f) { return (SendChar(ch)); }
int ferror(FILE *f)
{
/* Your implementation of ferror */
return EOF;
}
void _ttywrch(int ch) { SendChar(ch); }
void _sys_exit(int return_code)
{
label: goto label; /* endless loop */
}
//****************************************************************************
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(char *file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf(''Wrong parameters value: file %s on line %d
'', file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif
//****************************************************************************
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Posted on June 05, 2018 at 15:36
At 80 Mhz, and supporting the VCP via USART2 (PD5, PD6)
#include <stdio.h>
#include ''stm32l4xx_hal.h''
static void SystemClock_Config(void);
/* UART handler declaration */
static UART_HandleTypeDef UartHandle = { 0 };
//****************************************************************************
void USART2_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = { 0 };
__USART2_CLK_ENABLE();
__GPIOD_CLK_ENABLE();
/* UART RX/TX GPIO pin configuration */
GPIO_InitStruct.Pin = GPIO_PIN_5 | GPIO_PIN_6;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
/*## Configure the UART peripheral ######################################*/
/* Put the USART peripheral in the Asynchronous mode (UART Mode) */
/* UART1 configured as follow:
- Word Length = 8 Bits
- Stop Bit = One Stop bit
- Parity = NO parity
- BaudRate = 9600 baud
- Hardware flow control disabled (RTS and CTS signals) */
UartHandle.Instance = USART2;
UartHandle.Init.BaudRate = 115200;
UartHandle.Init.WordLength = UART_WORDLENGTH_8B;
UartHandle.Init.StopBits = UART_STOPBITS_1;
UartHandle.Init.Parity = UART_PARITY_NONE;
UartHandle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
UartHandle.Init.Mode = UART_MODE_TX_RX;
UartHandle.Init.OverSampling = UART_OVERSAMPLING_16;
#ifdef UART_ONE_BIT_SAMPLE_DISABLE
UartHandle.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
#endif
if (HAL_UART_Init(&UartHandle) != HAL_OK)
{
/* Initialization Error */
while(1);
}
}
//****************************************************************************
/**
* @brief Main program
* @param None
* @retval None
*/
int main(void)
{
HAL_Init();
/* Configure the System clock to have a frequency of 80 MHz */
SystemClock_Config();
USART2_Init();
printf(''
STM32L476G-DISCO
'');
printf(''Core=%d, %d MHz
'', SystemCoreClock, SystemCoreClock / 1000000);
printf(''APB1=%d
'', HAL_RCC_GetPCLK1Freq());
printf(''APB2=%d
'', HAL_RCC_GetPCLK2Freq());
/* Add your application code here
*/
/* Infinite loop */
while (1)
{
}
}
//****************************************************************************
/**
* @brief System Clock Configuration
* The system Clock is configured as follow :
* System Clock source = PLL (MSI)
* SYSCLK(Hz) = 80000000
* HCLK(Hz) = 80000000
* AHB Prescaler = 1
* APB1 Prescaler = 1
* APB2 Prescaler = 1
* MSI Frequency(Hz) = 4000000
* PLL_M = 1
* PLL_N = 40
* PLL_R = 2
* PLL_P = 7
* PLL_Q = 4
* Flash Latency(WS) = 4
* @param None
* @retval None
*/
static void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
/* MSI is enabled after System reset, activate PLL with MSI as source */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
RCC_OscInitStruct.MSIState = RCC_MSI_ON;
RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6;
RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
RCC_OscInitStruct.PLL.PLLM = 1;
RCC_OscInitStruct.PLL.PLLN = 40;
RCC_OscInitStruct.PLL.PLLR = 2;
RCC_OscInitStruct.PLL.PLLP = 7;
RCC_OscInitStruct.PLL.PLLQ = 4;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
/* Initialization Error */
while(1);
}
/* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2
clocks dividers */
RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK)
{
/* Initialization Error */
while(1);
}
}
//****************************************************************************
// Hosting of stdio functionality through SWV (Make SB14) and USART
//****************************************************************************
/* Implementation of putchar (also used by printf function to output data) */
int SendChar(int ch) /* Write character to Serial Port */
{
#if 1 // SWV
ITM_SendChar(ch); // From core_cm4.c
#endif
#if 1 // USART
while((USART2->ISR & USART_ISR_TXE) == 0); // Wait for Empty
USART2->TDR = ch; // Send Char
#endif
return(ch);
}
//****************************************************************************
#include <rt_misc.h>
#pragma import(__use_no_semihosting_swi)
struct __FILE { int handle; /* Add whatever you need here */ };
FILE __stdout;
FILE __stdin;
int fputc(int ch, FILE *f) { return (SendChar(ch)); }
int ferror(FILE *f)
{
/* Your implementation of ferror */
return EOF;
}
void _ttywrch(int ch) { SendChar(ch); }
void _sys_exit(int return_code)
{
label: goto label; /* endless loop */
}
//****************************************************************************
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(char *file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf(''Wrong parameters value: file %s on line %d
'', file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif
//****************************************************************************
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Posted on June 06, 2018 at 11:39 
I reckon I have eventually found the issue, it's because the revision of the board you are using and the one I have are different.
Note the revision changes above. What's more peculiar is PB3 is connected (or can be connected) not only to SWO but it's already connected to 3V3_REG_ON as can be seen in the below images. This signal is connected to mutliple points in the board.
I tried changing the jumper JP6 from 3V3_REG_ON to CR1 battery but the problem is ST-Link is getting completely disconnected from STM32L4 Hence, all I can do is use it only for SWD. My quest ends here I guess.
If I am right, the more interesting question is why would ST guys do such a thing? Why can't they use any other pin other than PB3? Hope someone from ST would comment on this.
