STM32+Keil 中使用printf函数

Keil不支持Host-semi机制，即不支持直接在IDE打印字符串。

那么只能通过程序向硬件串口发数据了，这样调用的时候用自定义的函数即可，也很方便，例如：

void send_char_to_usart(unsigned char c){}

但是可否直接使用printf函数呢？毕竟人家都做好了，我们给他定一个打印输出的接口就可以了，答案是肯定的，看ST的官方源码：

/**
******************************************************************************
* @file Lib_DEBUG/Lib_DEBUG_Example/main.c
* @author MCD Application Team
* @version V1.1.1
* @date 13-April-2012
* @brief Main program body
******************************************************************************
* @attention
*
*

? COPYRIGHT 2012 STMicroelectronics

*
* Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
* You may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.st.com/software_license_agreement_liberty_v2
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************
*/
/* Includes ------------------------------------------------------------------*/
#include "stm32l1xx.h"
#include "stm32l1xx_ip_dbg.h"
#include
#ifdef USE_STM32L152D_EVAL
#include "stm32l152d_eval.h"
#else
#include "stm32l152_eval.h"
#endif
/** @addtogroup STM32L1xx_StdPeriph_Examples
* @{
*/
/** @addtogroup Lib_DEBUG_Example
* @{
*/
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
USART_InitTypeDef USART_InitStructure;
/* Private function prototypes -----------------------------------------------*/
#ifdef __GNUC__
/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
set to Yes) calls __io_putchar() */
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */
/* Private functions ---------------------------------------------------------*/
/**
* @brief Main program
* @param None
* @retval None
*/
int main(void)
{
/*!< At this stage the microcontroller clock setting is already configured,
this is done through SystemInit() function which is called from startup
file (startup_stm32l1xx_xx.s) before to branch to application main.
To reconfigure the default setting of SystemInit() function, refer to
system_stm32l1xx.c file
*/
GPIO_InitTypeDef GPIOA_InitStructure;
/* USARTx configured as follow:
- BaudRate = 115200 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
USART_InitStructure.USART_BaudRate = 115200;
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;
STM_EVAL_COMInit(COM1, &USART_InitStructure);
/* Initialize all peripherals pointers */
IP_Debug();
printf("\r\n STM32l1xx Firmware Library compiled with FULL ASSERT function... \n\r");
printf("...Run-time checking enabled \n\r");
/* Simulate wrong parameter passed to library function ---------------------*/
/* To enable SPI1 clock, RCC_APB2PeriphClockCmd function must be used and
not RCC_APB1PeriphClockCmd */
RCC_APB1PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
/* Some member of GPIOA_InitStructure structure are not initialized */
GPIOA_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIOA_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
/*GPIOA_InitStructure.GPIO_Speed = GPIO_Speed_40MHz;*/
GPIOA_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIOA_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIOA_InitStructure);
while (1)
{
}
}
#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(uint8_t* file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number */
printf("\n\r Wrong parameter value detected on\r\n");
printf(" file %s\r\n", file);
printf(" line %d\r\n", line);
/* Infinite loop */
/* while (1)
{
} */
}
#endif
/**
* @brief Retargets the C library printf function to the USART.
* @param None
* @retval None
*/
PUTCHAR_PROTOTYPE
{
/* Place your implementation of fputc here */
/* e.g. write a character to the USART */
USART_SendData(EVAL_COM1, (uint8_t) ch);
/* Loop until the end of transmission */
while(USART_GetFlagStatus(EVAL_COM1, USART_FLAG_TC) == RESET)
{
}
return ch;
}
/**
* @}
*/
/**
* @}
*/
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/