GP2D12红外测距传感器原理与单片机源程序等详细资料 -

里面有作者根据 GP2D12 特性建立的数学模型（线性化公式），并预留的使用者输入参数的地方，只需按其要求填入：
AD 的位数、AD 供电电压（满量程），并采集 8 点（10cm 间隔）GP2D12  的输出电压，填入表中，它就可自动生成线性化公式的参数，提供了整形和浮点两种格式，还附有由此产生的结果与实际的偏差表，并用生动的图形表示，十分直观、实用。
此表可在embedream的相关资料中下载，本该提供它的原始链接，无奈现在没有了，只找到了一个类似的文档  —  Sharp IR Range Finder Voltage-to-Range Conversion Article 内容也是讨论线性化的，读者不妨一读。配合此文也许更容易理解使用那张Excel 表格。

根据上述公式及程序得到的结果如下：
GP2D12 不同颜色测距结果对比

第一列为实际距离，第二列障碍物表面为白纸，第三列障碍物为褐色木盒，读者可比照Excel 表中的数据，可以看出基本吻合。同时还可以从上面数据中看出，GP2D12 确实如其手册中所说，基本不受障碍物的颜色影响。

2.2  滤波
滤波主要解决两个问题，一是在GP2D12恒定输出阶段，按应用指南的分析，有不小的噪声，需要通过滤波消除。
二是由于其非连续测量的特性，导致其测量连续变化的距离时，输出是阶跃形式的，这对程序判断极为不利，为了弱化这个影响，也期望通过滤波实现。
根据 GP2D12 的手册，其测量周期为  40ms  左右（38ms），综合小车单片机的内存及处理需求，采用 5ms 采样一次，取最近 8 次的结果平均值的滤波方式，也就是说，一个测量周期采 8 个数据平均。
这样处理可以降低噪声的影响，这点容易理解。至于弱化阶跃信号，不知读者是否认同？
我是这样考虑：在出现阶跃信号时，8 个数据中随着时间推移，新的信号所占的权重不断加大，使得信号逐渐从前一个信号平缓的过渡到新的信号上。但是这样处理，导致了距离信号反映滞后，要到下一个信号快到时，本次的输出才接近本次的信号。就这一点而言，似乎有些不尽合理，有待读者深入探讨。

红外测试数据：

10cm 11.55--11.66
15cm  16.15--16.38
16.5cm  17.46--17.92
18cm 20.01--20.13
19cm  19.44--19.81
20cm  20.01--20.15
22cm  21.56--21.82
23cm  23.20--23.66
24.5cm  23.96--24.23
28cm  27.39--27.93

stm32单片机红外测距源程序如下:

* File Name : main.c
* Author : MCD Application Team
* Version : V1.0
* Date : 10/08
* Description : Main program body
********************************************************************************
* THE PRESENT SOFTWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
* WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.
* AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT,
* INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE
* CONTENT OF SUCH SOFTWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING
* INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
*******************************************************************************/
/* Includes ------------------------------------------------------------------*/
#include "stm32f10x_lib.h"
#include "stdio.h"
/* Private macro -------------------------------------------------------------*/
#define countof(a) (sizeof(a) / sizeof(*(a)))
/* Private typedef -----------------------------------------------------------*/
#define TxBufferSize (countof(TxBuffer) - 1)
/* Private define ------------------------------------------------------------*/
u8 TxBuffer[] = "\n\rADC Example1: ADC TO DMA TO UART1\n\r";
u8 TxCounter = 0;
/* Private define ------------------------------------------------------------*/
#define ADC1_DR_Address ((u32)0x4001244C)
/* Private variables ---------------------------------------------------------*/
USART_InitTypeDef USART_InitStructure;
ADC_InitTypeDef ADC_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
vu16 ADC_ConvertedValue;
ErrorStatus HSEStartUpStatus;
/* Private function prototypes -----------------------------------------------*/
void RCC_Configuration(void);
void GPIO_Configuration(void);
void NVIC_Configuration(void);
/* Private functions ---------------------------------------------------------*/
void Delay_us(unsigned short us)
{
unsigned short i;
while(us--)
{
for(i=0;i<10;i++);
}
}
void Delay_ms(unsigned short ms)
{
unsigned short i;
while(ms--)
{
for(i=0;i<10000;i++);
}
}
//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));
}
/*******************************************************************************
* Function Name : main
* Description : Main program
* Input : None
* Output : None
* Return : None
*******************************************************************************/
int main(void)
{
//unsigned char i=1;
unsigned long Tmp_Dat,i=1;
float distance,sum=0;
#ifdef DEBUG
debug();
#endif
/* System clocks configuration ---------------------------------------------*/
RCC_Configuration();
/* NVIC configuration ------------------------------------------------------*/
NVIC_Configuration();
/* GPIO configuration ------------------------------------------------------*/
GPIO_Configuration();
/* USART1 configuration ------------------------------------------------------*/
/* USART1 configured as follow:
- BaudRate = 9600 baud
- Word Length = 8 Bits
- Two Stop Bit
- Odd parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
- USART Clock disabled
- USART CPOL: Clock is active low
- USART CPHA: Data is captured on the second edge
- USART LastBit: The clock pulse of the last data bit is not output to
the SCLK pin
*/
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_InitStructure.USART_Clock = USART_Clock_Disable;
USART_InitStructure.USART_CPOL = USART_CPOL_Low;
USART_InitStructure.USART_CPHA = USART_CPHA_2Edge;
USART_InitStructure.USART_LastBit = USART_LastBit_Disable;
/* Configure the USART1 */
USART_Init(USART1, &USART_InitStructure);
/* Enable the USART Transmoit interrupt: this interrupt is generated when the
USART1 transmit data register is empty */
USART_ITConfig(USART1, USART_IT_TXE, ENABLE);
/* Enable the USART Receive interrupt: this interrupt is generated when the
USART1 receive data register is not empty */
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
/* Enable USART1 */
USART_Cmd(USART1, ENABLE);
/* DMA channel1 configuration ----------------------------------------------*/
DMA_DeInit(DMA_Channel1);
DMA_InitStructure.DMA_PeripheralBaseAddr = ADC1_DR_Address;
DMA_InitStructure.DMA_MemoryBaseAddr = (u32)&ADC_ConvertedValue;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
DMA_InitStructure.DMA_BufferSize = 1;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA_Channel1, &DMA_InitStructure);
/* Enable DMA channel1 */
DMA_Cmd(DMA_Channel1, ENABLE);
/* ADC1 configuration ------------------------------------------------------*/
ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_InitStructure.ADC_ScanConvMode = ENABLE;
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfChannel = 1;
ADC_Init(ADC1, &ADC_InitStructure);
/* ADC1 regular channel1 configuration */
ADC_RegularChannelConfig(ADC1, ADC_Channel_15, 1, ADC_SampleTime_55Cycles5);
/* Enable ADC1 DMA */
ADC_DMACmd(ADC1, ENABLE);
/* Enable ADC1 */
ADC_Cmd(ADC1, ENABLE);
/* Enable ADC1 reset calibaration register */
ADC_ResetCalibration(ADC1);
/* Check the end of ADC1 reset calibration register */
while(ADC_GetResetCalibrationStatus(ADC1));
/* Start ADC1 calibaration */
ADC_StartCalibration(ADC1);
/* Check the end of ADC1 calibration */
while(ADC_GetCalibrationStatus(ADC1));
/* Start ADC1 Software Conversion */
ADC_SoftwareStartConvCmd(ADC1, ENABLE);
for(i=0;i<TxBufferSize;i++)
{
/* Write one byte to the transmit data register */
USART_SendData(USART1, TxBuffer[TxCounter++]);
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
}
while (1)
{
Delay_ms(1000);
Tmp_Dat = ADC_ConvertedValue;
distance = (1/(Tmp_Dat*0.0000228324+0.00140335))-4.0;
printf("\n%ld\n",Tmp_Dat);
printf("%.2f",distance);
Tmp_Dat = Tmp_Dat*3300/0x0fff;
TxBuffer[0] = Tmp_Dat/1000+'0';
TxBuffer[1] = '.';
TxBuffer[2] = (Tmp_Dat%1000)/100+'0';
TxBuffer[3] = (Tmp_Dat%100)/10+'0';
TxBuffer[4] = Tmp_Dat%10+'0';
TxBuffer[5] = 'V';
USART_SendData(USART1, '[');
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
USART_SendData(USART1, TxBuffer[0]);
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
USART_SendData(USART1, TxBuffer[1]);
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
USART_SendData(USART1, TxBuffer[2]);
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
USART_SendData(USART1, TxBuffer[3]);
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
USART_SendData(USART1, TxBuffer[4]);
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
USART_SendData(USART1, TxBuffer[5]);
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
USART_SendData(USART1, ']');
while (!(USART1->SR & USART_FLAG_TXE)); //等待缓冲区空
while (!(USART1->SR & USART_FLAG_TC)); //等待发送完成
printf("\n");
}
}
/*******************************************************************************
* Function Name : RCC_Configuration
* Description : Configures the different system clocks.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void RCC_Configuration(void)
{
/* RCC system reset(for debug purpose) */
RCC_DeInit();
/* Enable HSE */
RCC_HSEConfig(RCC_HSE_ON);
/* Wait till HSE is ready */
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if(HSEStartUpStatus == SUCCESS)
{
/* Enable Prefetch Buffer */
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
/* Flash 2 wait state */
FLASH_SetLatency(FLASH_Latency_2);
/* HCLK = SYSCLK */
RCC_HCLKConfig(RCC_SYSCLK_Div1);
/* PCLK2 = HCLK */
RCC_PCLK2Config(RCC_HCLK_Div1);
/* PCLK1 = HCLK/2 */
RCC_PCLK1Config(RCC_HCLK_Div2);
/* ADCCLK = PCLK2/4 */
RCC_ADCCLKConfig(RCC_PCLK2_Div4);
/* PLLCLK = 8MHz * 7 = 56 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_7);
/* Enable PLL */
RCC_PLLCmd(ENABLE);
/* Wait till PLL is ready */
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
{
}
/* Select PLL as system clock source */
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
/* Wait till PLL is used as system clock source */
while(RCC_GetSYSCLKSource() != 0x08)
{
}
}
/* Enable peripheral clocks --------------------------------------------------*/
/* Enable DMA clock */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA, ENABLE);
/* Enable ADC1 and GPIOC clock */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1 | RCC_APB2Periph_GPIOC, ENABLE);
/* Enable GPIOA and USART1 clocks */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);
}
/*******************************************************************************
* Function Name : GPIO_Configuration
* Description : Configures the different GPIO ports.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* Configure PC.05 (ADC Channel15) as analog input -------------------------*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
GPIO_Init(GPIOC, &GPIO_InitStructure);
/* Configure USART1 Tx (PA.09) as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Configure USART1 Rx (PA.10) as input floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
/*******************************************************************************
* Function Name : NVIC_Configuration
* Description : Configures Vector Table base location.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void NVIC_Configuration(void)
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