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本人新手，编写了一段TM7705 AD转换的程序，采用了返回值调用方式，编译倒是通过了，仅出现了一条警告“: statement is unreachable”，提示程序无法达到这。本人想向大家请教，如何正确在主函数中调用子函数的返回值呢。主程序如下： #include "public.h" #include "AD7705.h" #include "systick.h" #include "gui.h" #include "led.h" #include "printf.h" /**************************************************************************** * Function Name : main * Description : Main program. * Input : None * Output : None * Return : None ****************************************************************************/ u16 intvalue; int main() { u8 dat[6],j; u16 value; float ad; TFT_Init(); //TFT³õʼ»¯ //AD7705_AllInit(); //ADC³õʼ»¯ LED_Init(); //LED¶Ë¿Ú³õʼ»¯ printf_init();//printf³õʼ»¯ TFT_ClearScreen(BLACK); GUI_Show12ASCII(10,10,"This is a ADC1-Channel1-PA1 Check!",YELLOW,BLACK); GUI_Show12ASCII(10,100,"The AD Value is:",YELLOW,BLACK); while(1) { AD7705_AllInit(); //ADC³õʼ» } if(j>1) 警告提示无法执行到这 { j=0; GPIO_SetBits(GPIOC,GPIO_Pin_0); } else { j++; GPIO_ResetBits(GPIOC,GPIO_Pin_0); } intvalue= ReadAD7705(); delay_ms(100); intvalue=intvalue/10; ad=value*3.3/65536; intvalue=(u16)(ad*100); dat[0]=intvalue/100+0x30; dat[1]='.'; dat[2]=intvalue%100/10+0x30; dat[3]=intvalue%100%10+0x30; dat[4]='V'; dat[5]='\0'; GUI_Show12ASCII(160,100,dat,RED,BLACK); } 调用的TM7705采样子程序 #include "public.h" u8 SPIx_ReadWriteByte(u8 TxData); void RCC_Configuration(void); void SPIx_Init(void); void Delay(vu32 nCount) { for(; nCount != 0; nCount--); } void GPIO_Configuration(void)//DRDY { GPIO_InitTypeDef GPIO_InitStructure; GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOC, &GPIO_InitStructure); } /********ÅäÖÃϵͳʱÖÓ,ʹÄܸ÷ÍâÉèʱÖÓ***********/ void RCC_Configuration(void) { RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA |RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO |RCC_APB2Periph_SPI1, ENABLE ); } /********AD7705³õʼ»¯º¯Êý***********/ void AD7705_Init(void) { unsigned char i ; for(i = 0; i < 100; i++) { SPIx_ReadWriteByte(0xFF); //³ÖÐøDIN¸ßµçƽд²Ù×÷£¬»Ö¸´AD7705½Ó¿Ú } SPIx_ReadWriteByte(0x20) ; //ͨµÀ1 ,ÏÂÒ»¸öдʱÖӼĴæÆ÷ Delay(1000); SPIx_ReadWriteByte(0x0E) ; //дʱÖӼĴæÆ÷ÉèÖøüÐÂËÙÂÊΪ200Hz Delay(1000); SPIx_ReadWriteByte(0x10) ; //ͨµÀ1 ,ÏÂÒ»¸öдÉèÖüĴæÆ÷ Delay(1000); SPIx_ReadWriteByte(0x44) ; //дÉèÖüĴæÆ÷ ,ÉèÖóÉË«¼«ÐÔ¡¢ÎÞ»º³å¡¢ÔöÒæΪ1¡¢Â˲¨Æ÷¹¤×÷¡¢×ÔУ׼ Delay(1000000); } /********¶Á16λÊý¾Ý************/ u16 ReadAD7705_16BitValue(void) { unsigned long DataL = 0; unsigned long DataH = 0; unsigned long Ret = 0; DataH = SPIx_ReadWriteByte(0xFF); DataH = DataH << 8; DataL = SPIx_ReadWriteByte(0xFF); Ret = DataH | DataL; return(Ret) ; } /********¶ÁÈ¡AD7705µÚһͨµÀÊý¾Ý************/ u16 ReadAD7705(void) { u8 i; unsigned long Ret = 0; for(i=0;i<10;i++) { SPIx_ReadWriteByte(0x38) ; //ÉèÖöÁµ±Ç°Í¨µÀÊý¾Ý while(GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_4 == 1)); Ret =Ret+ ReadAD7705_16BitValue(); } return Ret; 需要在主函数中调用该采样值并处理 } /****************************SPI³õʼ»¯*************************/ //SPI¿Ú³õʼ»¯ //ÕâÀïÕëÊǶÔSPI1µÄ³õʼ»¯ void SPIx_Init(void) { SPI_InitTypeDef SPI_InitStructure; GPIO_InitTypeDef GPIO_InitStructure; /* Configure SPI1 pins: SCK, MISO and MOSI */ //SCLK,DIN,DOUT GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //¸´ÓÃÍÆÍìÊä³ö GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOA, &GPIO_InitStructure); /* Configure I/O for Flash Chip select */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; //SPI CS GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; //¸´ÓÃÍÆÍìÊä³ö GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOC, &GPIO_InitStructure); /* Deselect the FLASH: Chip Select high */ GPIO_SetBits(GPIOC,GPIO_Pin_5); GPIO_SetBits(GPIOC,GPIO_Pin_4); SPI_Cmd(SPI1, DISABLE); //²»Ê¹ÄÜSPIÍâÉè ×Ô¼º¼ÓÉÏ /* SPI1 configuration */ SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex; //ÉèÖÃSPIµ¥Ïò»òÕßË«ÏòµÄÊý¾Ýģʽ:SPIÉèÖÃΪ˫ÏßË«ÏòÈ«Ë«¹¤ SPI_InitStructure.SPI_Mode = SPI_Mode_Master; //ÉèÖÃSPI¹¤×÷ģʽ:ÉèÖÃΪÖ÷SPI SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b; //ÉèÖÃSPIµÄÊý¾Ý´óС:SPI·¢ËͽÓÊÕ8λ֡½á¹¹ SPI_InitStructure.SPI_CPOL = SPI_CPOL_High; //Ñ¡ÔñÁË´®ÐÐʱÖÓµÄÎÈ̬:ʱÖÓÐü¿Õ¸ß SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge; //Êý¾Ý²¶»ñÓÚµÚ¶þ¸öʱÖÓÑØ SPI_InitStructure.SPI_NSS = SPI_NSS_Soft; //NSSÐźÅÓÉÓ²¼þ£¨NSS¹Ü½Å£©»¹ÊÇÈí¼þ£¨Ê¹ÓÃSSI룩¹ÜÀí:ÄÚ²¿NSSÐźÅÓÐSSIλ¿ØÖÆ SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_64; //¶¨Ò岨ÌØÂÊÔ¤·ÖƵµÄÖµ:²¨ÌØÂÊÔ¤·ÖƵֵΪ256 SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB; //Ö¸¶¨Êý¾Ý´«Êä´ÓMSBλ»¹ÊÇLSBλ¿ªÊ¼:Êý¾Ý´«Êä´ÓMSBλ¿ªÊ¼ SPI_InitStructure.SPI_CRCPolynomial = 7; //CRCÖµ¼ÆËãµÄ¶àÏîʽ SPI_Init(SPI1, &SPI_InitStructure); //¸ù¾ÝSPI_InitStructÖÐÖ¸¶¨µÄ²ÎÊý³õʼ»¯ÍâÉèSPIx¼Ä´æÆ÷ //SPI1->CR1|=1<<6; //SPIÉ豸ʹÄÜ /* Enable SPI1 */ SPI_Cmd(SPI1, ENABLE); //ʹÄÜSPIÍâÉè SPIx_ReadWriteByte(0xff);//Æô¶¯´«Êä } //SPIx ¶Áдһ¸ö×Ö½Ú //TxData:ҪдÈëµÄ×Ö½Ú //·µ»ØÖµ:¶ÁÈ¡µ½µÄ×Ö½Ú u8 SPIx_ReadWriteByte(u8 TxData) { GPIO_ResetBits(GPIOC,GPIO_Pin_5); while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET); //¼ì²éÖ¸¶¨µÄSPI±ê־λÉèÖÃÓë·ñ:·¢ËÍ»º´æ¿Õ±ê־λ /* Send byte through the SPI1 peripheral */ SPI_I2S_SendData(SPI1, TxData); //ͨ¹ýÍâÉèSPIx·¢ËÍÒ»¸öÊý¾Ý /* Wait to receive a byte */ while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET); //¼ì²éÖ¸¶¨µÄSPI±ê־λÉèÖÃÓë·ñ:½ÓÊÜ»º´æ·Ç¿Õ±êÖ¾ /* Return the byte read from the SPI bus */ GPIO_SetBits(GPIOC,GPIO_Pin_5); return SPI_I2S_ReceiveData(SPI1); //·µ»Øͨ¹ýSPIx×î½ü½ÓÊÕµÄÊý¾Ý } /********AD7705ÍêÕû³õʼ»¯º¯Êý***********/ void AD7705_AllInit(void) { RCC_Configuration(); GPIO_Configuration(); SPIx_Init(); AD7705_Init(); } |
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2.从哪抄的代码，看似“奇怪”的问题都是自己粗心导致的。
3.即使不是抄的，简单的几行代码逐行跑一遍调试立马看出问题了，太懒！
4.什么叫“函数返回调用”？！！
5.函数调用就是函数调用，哪来的“函数返回调用”！基本概念不要搞错了，也别胡乱起名字，不然谁回答你的问题，况且代码又很长。
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