1. // 添加这个函数
   
2. int fputc(int ch,FILE *f)
   # f5 P4 |& g$ Q* j$ X; Z) I
3. {
   ! h) N& c. z& h' {
4.     uint8_t temp[1]={ch};
   ! ]9 I' O4 Q/ x+ v# l
5.     HAL_UART_Transmit(&UartHandle,temp,1,2);
   
6. }

复制代码

MDK设置：勾选Use Micro LIB

' V- L; L, i5 f0 R) y! _) S) e

测试板子：STM32F746NG-DISCOVERY

main.c文件

1. /* Includes ------------------------------------------------------------------*/
   
2. #include "main.h"
   
3. #include <stdio.h>
   
4. /** @addtogroup STM32F7xx_HAL_Examples
   ( ]: B% ?1 f- s2 Z: B$ s; l
5.   * @{
   
6.   */
   
7. 
   
8. /** @addtogroup UART_TwoBoards_ComDMA
   $ n2 d. ?. a- Z) R  c
9.   * @{
   
10.   */
    
11. 
    ! }' Q  P5 z, Y: x4 r) ~
12. /* Private typedef -----------------------------------------------------------*/
    
13. /* Private define ------------------------------------------------------------*/
    
14. #define TRANSMITTER_BOARD
    
15. 
    0 G0 h# C. i1 O9 L
16. /* Private macro -------------------------------------------------------------*/
    
17. /* Private variables ---------------------------------------------------------*/
    
18. /* UART handler declaration */
    3 ~# s/ t" I& W) q
19. UART_HandleTypeDef UartHandle;
    
20. __IO ITStatus UartReady = RESET;
    
21. __IO uint32_t UserButtonStatus = 0;  /* set to 1 after User Button interrupt  */
    
22. 
    
23. /* Buffer used for transmission */
    
24. uint8_t aTxBuffer[] = " ****UART_TwoBoards communication based on DMA****  ****UART_TwoBoards communication based on DMA****  ****UART_TwoBoards communication based on DMA**** ";
      _0 E: M6 z0 ]+ ?. X& t/ V2 D0 u
25. 
    7 ^6 G( v; D$ x" q3 b, f) s
26. /* Buffer used for reception */
    2 `( i& T6 p6 ~0 D: D% H
27. uint8_t aRxBuffer[RXBUFFERSIZE];
    
28. 
    
29. /* Private function prototypes -----------------------------------------------*/
    
30. void SystemClock_Config(void);
    3 ~3 W+ w" ?, l- t3 H2 O1 N( w
31. static void Error_Handler(void);
    2 r8 W& m1 ?/ [: O1 ~2 W
32. static uint16_t Buffercmp(uint8_t* pBuffer1, uint8_t* pBuffer2, uint16_t BufferLength);
    
33. static void MPU_Config(void);
    
34. static void CPU_CACHE_Enable(void);
    - n( w$ I' a/ `: B5 i( P
35. 
    
36. /* Private functions ---------------------------------------------------------*/
    " N, y3 k5 U. A* d' C* r, O
37. UART_HandleTypeDef UartHandle;
    ; \& ?/ k! a9 J; v% K, b) \
38. uint8_t sendbuf[]="send ok ";
    ( Z' x' F# U6 J# C& t
39. 
    
40. // 添加这个函数
    
41. int fputc(int ch,FILE *f)
    - }) v8 s  M2 ]! G6 g
42. {
    
43.     uint8_t temp[1]={ch};
    ( W. E+ [. U2 @# r! }
44.     HAL_UART_Transmit(&UartHandle,temp,1,2);
    5 ~+ t! z6 m. z' S* G$ B0 D
45. }
    ' w! W" f8 O: u* T
46. 
    # a! E3 N  n5 n. N6 n
47. /**
    
48.   * @brief  Main program
    & [2 A' u! ]# L' ]. e( d& @
49.   * @param  None
    
50.   * @retval None
    # d2 g# H0 n: w/ N2 n* W
51.   */
    
52. int main(void)
    
53. {
    
54.   /* Configure the MPU attributes as Write Through */
    4 Z* Z$ I- z5 k. D
55.   MPU_Config();
    
56. 
    0 L( H2 A( [& u8 f- O3 H: B) M) v
57.   /* Enable the CPU Cache */
    * X. F3 K5 r- |
58.   CPU_CACHE_Enable();
    
59.   /* STM32F7xx HAL library initialization:
    
60.        - Configure the Flash ART accelerator
    
61.        - Systick timer is configured by default as source of time base, but user
    
62.          can eventually implement his proper time base source (a general purpose
    1 F$ Q9 E+ l" x
63.          timer for example or other time source), keeping in mind that Time base
    
64.          duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and
    1 q0 t% G, p5 ?
65.          handled in milliseconds basis.
    : K7 m1 V* l( C- c% b1 Z3 m0 D, |
66.        - Set NVIC Group Priority to 4
    
67.        - Low Level Initialization
    
68.      */
    , e  ^( `. W3 E; ^) S) l
69.   HAL_Init();
    
70. 
    4 J" _# U! Q! `) k) y2 `& w
71.   /* Configure the system clock to 216 MHz */
    & @( U& f9 B- D, B1 D  {  ?  q5 h
72.   SystemClock_Config();
    
73.   
    * ^" K. @9 \7 }0 ~! t0 A5 b
74.   /* Configure LED1 */
    - j7 f7 p+ W! F: O8 P
75.   BSP_LED_Init(LED1);
    , m; [/ M7 ^4 [# d
76.    
    
77.   UartHandle.Instance        = DISCOVERY_COM1;
    ) u1 o8 q% ^, L
78. 
    3 b, g9 d0 J  e
79.   UartHandle.Init.BaudRate   = 9600;
    2 j* q" B3 N. {4 i1 n
80.   UartHandle.Init.WordLength = UART_WORDLENGTH_8B;
    
81.   UartHandle.Init.StopBits   = UART_STOPBITS_1;
    
82.   UartHandle.Init.Parity     = UART_PARITY_NONE;
    + `3 G5 l1 u5 h" ~
83.   UartHandle.Init.HwFlowCtl  = UART_HWCONTROL_NONE;
    
84.   UartHandle.Init.Mode       = UART_MODE_TX_RX;
    % Y  N5 Y+ O: e* B6 p1 o1 z
85.     BSP_COM_DeInit(COM1,&UartHandle);
    % }' A) X7 @( Q' z/ U
86.     BSP_COM_Init(COM1,&UartHandle);
    # H* ~+ H1 ?! B. J( x$ X
87.    
    
88. //    HAL_UART_Transmit(&UartHandle,sendbuf,sizeof(sendbuf),10);
    - U, K5 I# O+ B3 V* C9 M# d, W
89.   /* Configure User push-button in Interrupt mode */
    ' C% o) j. R6 u" y6 h! D, G
90.   BSP_PB_Init(BUTTON_KEY, BUTTON_MODE_EXTI);
    $ t2 J5 x1 }/ P" l. b4 x
91.   
    
92.   /* Wait for User push-button press before starting the Communication.
    
93.      In the meantime, LED1 is blinking */
    ) b- [) L5 k% v. H2 x, ]
94.     printf("hello");
    
95.    
    
96.    
    & G. ?" c* ^0 ], W- c8 d* T. V
97.   while(UserButtonStatus == 0)
    / F  I1 G) E# [/ n
98.   {
    
99.       /* Toggle LED1*/
    ; L( u( _  C- P' s4 h
100.       BSP_LED_Toggle(LED1);
     
101.       HAL_Delay(100);
     * j8 ]5 ?' g  Y0 l1 k
102.   }
     
103.   /* Turn on LED1 if test passes then enter infinite loop */
     ) u- f5 E( G8 H& v# y! C
104.   BSP_LED_On(LED1);
     
105.   /* Infinite loop */
     
106.   while (1)
     3 F% n; S0 A* H  e/ |0 e: b( w
107.   {
     , h* U4 L. c9 ^6 ?# @
108.   }
     ' z2 y9 {& F  x% w
109. }
     
110. 
     
111. /**
     " F3 f& m9 B* ?
112.   * @brief  System Clock Configuration
     
113.   *         The system Clock is configured as follow :
     , X6 l4 H9 k. G9 F
114.   *            System Clock source            = PLL (HSE)
     
115.   *            SYSCLK(Hz)                     = 216000000
     
116.   *            HCLK(Hz)                       = 216000000
     
117.   *            AHB Prescaler                  = 1
     
118.   *            APB1 Prescaler                 = 4
     # P3 R5 g3 k. @: n8 E4 |6 ?# K
119.   *            APB2 Prescaler                 = 2
     
120.   *            HSE Frequency(Hz)              = 25000000
     
121.   *            PLL_M                          = 25
     
122.   *            PLL_N                          = 432
     # R6 S4 T' t# T( |4 Z0 f1 t4 e
123.   *            PLL_P                          = 2
     
124.   *            PLL_Q                          = 9
     
125.   *            VDD(V)                         = 3.3
     
126.   *            Main regulator output voltage  = Scale1 mode
     
127.   *            Flash Latency(WS)              = 7
     
128.   * @param  None
     
129.   * @retval None
     ; A) |5 J4 D- Q% H: f& c+ Z
130.   */
     4 H4 c5 W& M6 s8 b# ~
131. void SystemClock_Config(void)
     $ J2 H$ j7 l- o# ]4 T0 B
132. {
     
133.   RCC_ClkInitTypeDef RCC_ClkInitStruct;
     
134.   RCC_OscInitTypeDef RCC_OscInitStruct;
     / ]1 j' g2 l4 z* v0 P$ q
135.   HAL_StatusTypeDef ret = HAL_OK;
     - [0 N2 W6 ^. t8 Z- A. w9 v
136. 
     8 X: _0 l: G. _8 O
137.   /* Enable HSE Oscillator and activate PLL with HSE as source */
     " o+ g; L8 f2 k4 E
138.   RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
     ) F- K4 ?" T. f( E! O6 F/ Q! Q9 W
139.   RCC_OscInitStruct.HSEState = RCC_HSE_ON;
     
140.   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
     ) b0 r0 _% H9 B: |$ Y
141.   RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
     
142.   RCC_OscInitStruct.PLL.PLLM = 25;
     
143.   RCC_OscInitStruct.PLL.PLLN = 432;
     8 p  Z: E; I& ]2 q( A
144.   RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
     
145.   RCC_OscInitStruct.PLL.PLLQ = 9;
     
146.   
     
147.   ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
     
148.   if(ret != HAL_OK)
     
149.   {
     
150.     while(1) { ; }
     
151.   }
     . v  ^; D9 [5 t9 W1 h- k. X
152.   
     
153.   /* Activate the OverDrive to reach the 216 MHz Frequency */  
     
154.   ret = HAL_PWREx_EnableOverDrive();
     
155.   if(ret != HAL_OK)
     
156.   {
     + X8 l4 b0 z4 v
157.     while(1) { ; }
     % F% Z8 ?& m' y5 v* m+ B
158.   }
     5 Z& G  R3 V& s, U+ \, C/ L, o; D
159.   
     5 L! r* ]  G1 n& w7 f
160.   /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
     
161.   RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
     ! L/ p; G+ l  m9 z2 F
162.   RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
     
163.   RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
     ) E7 h9 ~: o0 Y/ E
164.   RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;  
     
165.   RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
     ; _( _, s. c: B& _
166.   
     4 z% L6 T4 x7 i' Q- ~" T
167.   ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7);
     
168.   if(ret != HAL_OK)
     
169.   {
     
170.     while(1) { ; }
     
171.   }  
     0 ~# B4 n  f1 s
172. }
     5 P& d" p' i! ]
173. 
     
174. /**
     4 m5 H, l% b! O% y+ l  W! K5 R. O
175.   * @brief  Tx Transfer completed callback
     2 N* M/ R9 C" v/ L! q& [, p
176.   * @param  UartHandle: UART handle.
     7 v4 I4 h0 A9 ?# H5 f
177.   * @note   This example shows a simple way to report end of DMA Tx transfer, and
     
178.   *         you can add your own implementation.
     
179.   * @retval None
     
180.   */
     ) V6 m+ @% U. k+ _+ z/ y
181. void HAL_UART_TxCpltCallback(UART_HandleTypeDef *UartHandle)
     # q6 ?( d% j- d) Y  x
182. {
     
183.   /* Set transmission flag: trasfer complete*/
     7 Y* e. O1 K4 t* X/ d; U
184.   UartReady = SET;
     . w' Z3 S& f4 Z" Z
185. 
     
186.   
     
187. }
     7 S8 n, [# ?( ^: t' y' C
188. 
     
189. /**
     
190.   * @brief  Rx Transfer completed callback
     3 C7 T6 q7 d) i7 w. \9 i; T  A" e
191.   * @param  UartHandle: UART handle
     + q$ \2 S) A  q0 f, ?6 K4 h
192.   * @note   This example shows a simple way to report end of DMA Rx transfer, and
     
193.   *         you can add your own implementation.
     
194.   * @retval None
     1 t) A5 T; S& _# Y4 G! f1 k1 K
195.   */
     * t& O9 G" D% z2 B( O- n
196. void HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle)
     
197. {
     
198.   /* Set transmission flag: trasfer complete*/
     
199.   UartReady = SET;
     
200. 
     ; s  u2 c% S# a0 A( g+ F/ \
201.   
     
202. }
     1 z/ D$ s" G! i! k: I
203. 
     
204. /**
     
205.   * @brief  UART error callbacks
     1 M8 K2 d7 i7 {+ f3 M( @! ~
206.   * @param  UartHandle: UART handle
     ( X9 Z9 T% R+ J. B+ p. ^
207.   * @note   This example shows a simple way to report transfer error, and you can
     ; G8 ]/ B4 p( j  U; N% k
208.   *         add your own implementation.
     6 \, P- e9 R3 V! o
209.   * @retval None
     " S7 d$ v. z" K6 A  @" [* @- Y
210.   */
     
211. void HAL_UART_ErrorCallback(UART_HandleTypeDef *UartHandle)
     1 K, i4 I$ a% S
212. {
     
213.     Error_Handler();
     8 X. V8 I, D; @/ H! [4 n/ B& I' ^
214. }
     1 X8 F- |# w: b7 Y- J
215. 
     
216. 
     
217. /**
     
218.   * @brief EXTI line detection callbacks
     # P$ I3 l, e% s  `- A) e
219.   * @param GPIO_Pin: Specifies the pins connected EXTI line
     
220.   * @retval None
     + W6 e+ X: u, b0 b6 W/ H, a' d* M
221.   */
     ) `/ S/ X2 l* n- p2 V: s
222. void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
     
223. {
     ! E; _  a! o/ Z
224.   if(GPIO_Pin == KEY_BUTTON_PIN)
     
225.   {  
     
226.     UserButtonStatus = 1;
     
227.   }
     
228. }
     
229. 
     
230. /**
     ; h$ `6 g; E7 f. e' x' S9 R( n
231.   * @brief  Compares two buffers.
     9 u1 k8 k% j- q) ~- C6 t
232.   * @param  pBuffer1, pBuffer2: buffers to be compared.
     8 U8 ?" @$ J- d7 [+ l) u
233.   * @param  BufferLength: buffer's length
     
234.   * @retval 0  : pBuffer1 identical to pBuffer2
     
235.   *         >0 : pBuffer1 differs from pBuffer2
     
236.   */
     # n- V8 L3 s8 h* I$ K: v
237. static uint16_t Buffercmp(uint8_t* pBuffer1, uint8_t* pBuffer2, uint16_t BufferLength)
     
238. {
     
239.   while (BufferLength--)
     
240.   {
     
241.     if ((*pBuffer1) != *pBuffer2)
     
242.     {
     : H$ Q' _  r" O7 o8 \6 c+ O
243.       return BufferLength;
     
244.     }
     
245.     pBuffer1++;
     
246.     pBuffer2++;
     
247.   }
     ) ~3 ]% c/ B( D
248. 
     % O* V6 Q0 z- P! `8 l' u
249.   return 0;
     
250. }
       X- Y: Z' t$ ~* q! L7 f0 ]% \
251. 
     
252. /**
     
253.   * @brief  This function is executed in case of error occurrence.
     ' K0 w. n1 x' e+ m
254.   * @param  None
     
255.   * @retval None
     / M, A, v, e4 V% V, Z: r% r+ [: V
256.   */
     
257. static void Error_Handler(void)
     
258. {
     
259.   /* Turn LED1 on */
     
260.   BSP_LED_On(LED1);
     
261.   while(1)
     
262.   {
     : g2 _! t+ n6 M. Q5 a- p3 ?+ ~
263.     /* Error if LED1 is slowly blinking (1 sec. period) */
     & g$ A' W5 T; `0 U+ H- I
264.     BSP_LED_Toggle(LED1);
     
265.     HAL_Delay(1000);
     
266.   }  
     7 n- X: n8 Z5 `
267. }
     # Y- y' }: ~4 B
268. 
     7 E$ O" I) h  `, Z% x- R
269. #ifdef  USE_FULL_ASSERT
     / {6 ~# D5 s- _. A+ b6 ?0 N1 h
270. 
     4 g) L3 @2 |0 ~+ f" S' n
271. /**
     
272.   * @brief  Reports the name of the source file and the source line number
     " `( W1 s8 `1 Y- G; b$ b
273.   *         where the assert_param error has occurred.
     : o' D* F" g; o; r) x' ~, M
274.   * @param  file: pointer to the source file name
     
275.   * @param  line: assert_param error line source number
     + h9 G" Q$ ~! W" Z6 @/ G% x
276.   * @retval None
     2 L- ~" h% J  x' |2 I( z4 |! D
277.   */
     
278. void assert_failed(uint8_t* file, uint32_t line)
     
279. {
     
280.   /* User can add his own implementation to report the file name and line number,
     
281.      ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
     & d; e4 @! _; f8 Q" r" W/ r
282. 
     
283.   /* Infinite loop */
     " g' g5 M* R3 H+ k' l8 k
284.   while (1)
     
285.   {
     
286.   }
     1 e, p- Q6 }. |4 ^' V+ x
287. }
     
288. #endif
     
289. 
     4 j7 j4 X4 ^3 ?4 W5 d0 \
290. /**
     5 w% u% ~5 k) {1 s- |0 v
291.   * @brief  Configure the MPU attributes as Write Through for SRAM1/2.
     3 V  L$ R0 z" F5 F0 N& S' K. P( V
292.   * @note   The Base Address is 0x20010000 since this memory interface is the AXI.
     
293.   *         The Region Size is 256KB, it is related to SRAM1 and SRAM2  memory size.
     
294.   * @param  None
     + ]7 T; G1 z1 v. n) V, Y7 S' O
295.   * @retval None
     ' v* L1 s5 T1 E# |9 n* I, {
296.   */
     4 _' H. |1 L1 E! y) S& U
297. static void MPU_Config(void)
     4 h' f$ ?/ I% x! f
298. {
     $ @5 P2 b$ p& u' i7 j, u* H
299.   MPU_Region_InitTypeDef MPU_InitStruct;
     
300.   
     
301.   /* Disable the MPU */
     
302.   HAL_MPU_Disable();
     2 k, u4 H7 f+ a4 @
303. 
     
304.   /* Configure the MPU attributes as WT for SRAM */
     
305.   MPU_InitStruct.Enable = MPU_REGION_ENABLE;
     
306.   MPU_InitStruct.BaseAddress = 0x20010000;
     
307.   MPU_InitStruct.Size = MPU_REGION_SIZE_256KB;
     + d4 n: c/ d& t9 D. l2 O5 D7 G
308.   MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
     , L' n8 i4 G' w" V6 |
309.   MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
     " N5 }+ \* v! ^% T! v5 {
310.   MPU_InitStruct.IsCacheable = MPU_ACCESS_CACHEABLE;
     
311.   MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
     
312.   MPU_InitStruct.Number = MPU_REGION_NUMBER0;
     
313.   MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
     " L  o" ?0 p1 ^
314.   MPU_InitStruct.SubRegionDisable = 0x00;
     1 B: Z3 h: y& K  J
315.   MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;
     ( \; C/ b/ v4 v; A
316. 
     4 B6 F0 J" @6 [: Z# `. T
317.   HAL_MPU_ConfigRegion(&MPU_InitStruct);
     
318. 
     
319.   /* Enable the MPU */
     ; f' X6 p7 C8 o& {' t8 E9 i
320.   HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
     ! P; L# Y; ]7 c6 g# R9 ^! v! A
321. }
     
322. 
     1 b& Q  q. m" D2 ], ]+ t
323. /**
     ! |9 @$ z; g. {1 I; |
324.   * @brief  CPU L1-Cache enable.
     - @* `& ?6 H3 w; T
325.   * @param  None
     
326.   * @retval None
     0 _; F$ \5 V. p% w+ X9 ?+ S
327.   */
     
328. static void CPU_CACHE_Enable(void)
     ) C9 U; L% l) X# D9 ]: p7 J6 i
329. {
     . v7 v+ F& `7 Y9 L
330.   /* Enable I-Cache */
     7 G/ \3 A. C- @# P2 s- F2 B7 M
331.   SCB_EnableICache();
     4 s8 N# i2 v) K
332. 
       ?  @' r- j+ ^) W2 W: \. f% a
333.   /* Enable D-Cache */
     
334.   SCB_EnableDCache();
     3 J9 x1 J$ {6 [+ b" B
335. }
     ) M2 X! \8 d4 ?" Y  t
336. 
     
337. /**
     
338.   * @}
     
339.   */
     ( |; v& X; a, e8 l6 ^6 |3 S
340. 
     
341. /**
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342.   * @}“stdio.h”
     
343.   */
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344. 
     
345. /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

复制代码

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今天调试了stm32f407的ADC，一切顺利，然而用串口发送ADC结果时都是16进制数，看着很不爽。于是打算用用牛B的“printf”函数，按照以前的做法，在main文件中添加了“stdio.h”，写好了“printf”函数，沏杯茶，打算边品茶边坐等结果，然而这一坐竟坐了半天也没见结果

。一调试发现程序停在了printf函数处，百思不得其解，百度之，得答案，不敢独享，分享如下：

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STM32串口通信中使用printf发送数据配置方法(开发环境 Keil RVMDK)

标签: STM32 串口通信 printf方法 2011-06-29 23:29

在STM32串口通信程序中使用printf发送数据，非常的方便。可在刚开始使用的时候总是遇到问题，常见的是硬件访真时无法进入main主函数，其实只要简单的配置一下就可以了。

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下面就说一下使用printf需要做哪些配置。

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有两种配置方法：

一、对工程属性进行配置，详细步骤如下

1、首先要在你的main 文件中 包含“stdio.h” （标准输入输出头文件）。

2、在main文件中重定义<fputc>函数 如下：

// 发送数据

int fputc(int ch, FILE *f)

{

USART_SendData(USART1, (unsigned char) ch);// USART1 可以换成 USART2 等

while (!(USART1->SR & USART_FLAG_TXE));

return (ch);

}

// 接收数据

int GetKey (void) {

while (!(USART1->SR & USART_FLAG_RXNE));

return ((int)(USART1->DR & 0x1FF));

}

这样在使用printf时就会调用自定义的fputc函数，来发送字符。

3、在工程属性的 “Target" -> "Code Generation" 选项中勾选 "Use MicroLIB"”

MicroLIB 是缺省C的备份库，关于它可以到网上查找详细资料。

至此完成配置，在工程中可以随意使用printf向串口发送数据了。

二、第二种方法是在工程中添加“Regtarge.c”文件

1、在main文件中包含 “stdio.h” 文件

2、在工程中创建一个文件保存为 Regtarge.c ， 然后将其添加工程中

在文件中输入如下内容（直接复制即可）

#include <stdio.h>

#include <rt_misc.h>

#pragma import(__use_no_semihosting_swi)

extern int SendChar(int ch); // 声明外部函数，在main文件中定义

extern int GetKey(void);

struct __FILE {

int handle; // Add whatever you need here

};

FILE __stdout;

FILE __stdin;

int fputc(int ch, FILE *f) {

return (SendChar(ch));

}

int fgetc(FILE *f) {

return (SendChar(GetKey()));

}

void _ttywrch(int ch) {

SendChar (ch);

}

int ferror(FILE *f) { // Your implementation of ferror

return EOF;

}

void _sys_exit(int return_code) {

label: goto label; // endless loop

}

3、在main文件中添加定义以下两个函数

int SendChar (int ch) {

while (!(USART1->SR & USART_FLAG_TXE)); // USART1 可换成你程序中通信的串口

USART1->DR = (ch & 0x1FF);

return (ch);

}

int GetKey (void) {

while (!(USART1->SR & USART_FLAG_RXNE));

return ((int)(USART1->DR & 0x1FF));

}

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