普中STM32-PZ6806L开发板(HAL库函数实现-访问多个温度传感器DS18B20)

简介

我们知道多个DS18B20的DQ线是可以被挂在一起的, 也就是一根线上可以访问不同的DS18B20而不会造成数据错乱, 怎么做到的，其实数据手册都有说到，就是靠64-bit ROM code 进行识别, 也可以理解成Serial Number进行识别, 因为主要差异还是在Serial Number上面;

电路图

两个DS18B20连接到一起

实现步骤

创建项目

基于上一篇普中STM32-PZ6806L开发板(HAL库函数实现-温度传感器DS18B20)

添加用户代码

获取DS18B20的Serial Number信息, 然后记录下来, 用于向指定DS18B20获取温度值

c 复制代码

typedef struct 
{
	uint8_t familyCode;
	uint8_t sns[6];
	uint8_t crc;
} SENSOR_DS18B20_SerialNumberInfo;


SENSOR_DS18B20_SerialNumberInfo SENSOR_DS18B20_GetSN(void)
{
	SENSOR_DS18B20_SerialNumberInfo info;
	uint8_t recvs[8] = { 0 };
	
	SENSOR_DS18B20_Reset ();
	HAL_Delay (1);
	SENSOR_DS18B20_Write (0x33);  // read rom
	HAL_Delay (1);
	
	// 1 byte -> family code
	// 2 ~ 7 byte -> serial number
 //  8 byte -> CRC8	
	recvs[0] = SENSOR_DS18B20_Read(); // family code
	info.familyCode = recvs[0];
	
	for (int i = 0; i < 6; ++i) // serial number
	{ 
		recvs[i+1] = SENSOR_DS18B20_Read();
		info.sns[i] = recvs[i+1];
	}
	recvs[7] = SENSOR_DS18B20_Read(); // CRC8
	info.crc = recvs[7];
	if (SENSOR_DS18B20_CRC8(recvs, 7) != recvs[7]) // CRC8 检查
	{
		info.familyCode = 0;
		memset(info.sns, 0, sizeof(info.sns)/sizeof(uint8_t));
		info.crc = 0; 
		return info; // CRC校验不一致
	}
	return info;
}

实现流程参考pdf

实现代码

c 复制代码

/* 两个DS18B20设备 */
#include <stdio.h>
#include <string.h>

/* DS18B20, 提前读取出来的SN&familyCode&CRC码 */
SENSOR_DS18B20_SerialNumberInfo  ds18b20_infos[] = 
{
	{ 0x28, { 0x2E, 0x7C, 0x04, 0x05, 0x00, 0x00 }, 0xCC },
	{ 0x28, { 0x2F, 0x7D, 0x10, 0x02, 0x01, 0x00 }, 0xBE }
};

/* 引脚重新设置为输入 */
static void SENSOR_DS18B20_SetPinInput(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin)
{
	GPIO_InitTypeDef GPIO_InitStruct;
	
	GPIO_InitStruct.Pin = GPIO_Pin;
	GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
	GPIO_InitStruct.Pull = GPIO_NOPULL;
	HAL_GPIO_Init(GPIOx, &GPIO_InitStruct);
}
/* 引脚重新设置为输出 */
static void SENSOR_DS18B20_SetPinOutput(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin)
{
	GPIO_InitTypeDef  GPIO_InitStruct;
	
	GPIO_InitStruct.Pin = GPIO_Pin;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
	HAL_GPIO_Init(GPIOx, &GPIO_InitStruct);
}

/*
	SENSOR_DS18B20_Reset :
	初始化，也是复位, 每次发送指令前的动作
		0 : 初始化失败
		1 : 初始化成功
*/
static uint8_t SENSOR_DS18B20_Reset(void)
{
	uint8_t res = 0;
	SENSOR_DS18B20_SetPinOutput(DS18B20_PORT, DS18B20_PIN);   // 引脚输出模式
	HAL_GPIO_WritePin (DS18B20_PORT, DS18B20_PIN, 0);  // 拉低引脚
	delay_us (480);   // 参考初始化时序图, 延时480us

	SENSOR_DS18B20_SetPinInput(DS18B20_PORT, DS18B20_PIN);    // set the pin as input
	delay_us (60);    // 15~60us等待DS18B20回复信息, 多等20us避免检测不到

	if ( !HAL_GPIO_ReadPin(DS18B20_PORT, DS18B20_PIN) )
		res = 1;  // 检测到低电平,  DS18B20有响应
	else 
		res = 0;

	delay_us (420); // 等待DS18B20结束响应

	return res;
}

/* 写流程 */
void SENSOR_DS18B20_Write(uint8_t data)
{
	/*
		按位写, 根据时序图, 按照写的 高电平的时序 和 低电平的时序进行延时
	*/
	for (int i = 0; i < 8; ++i)
	{

		if ((data & (1<<i))!=0) // 写1
		{
			SENSOR_DS18B20_SetPinOutput(DS18B20_PORT, DS18B20_PIN);  
			HAL_GPIO_WritePin(DS18B20_PORT, DS18B20_PIN, 0);  // 拉低
			delay_us (2);  // 低电平保持时间

			SENSOR_DS18B20_SetPinInput(DS18B20_PORT, DS18B20_PIN);  // 输入
			delay_us (60);  // 等待
		}
		else // 写0
		{
			SENSOR_DS18B20_SetPinOutput(DS18B20_PORT, DS18B20_PIN);
			HAL_GPIO_WritePin (DS18B20_PORT, DS18B20_PIN, 0);  // 拉低
			delay_us (60);  // 等待60us

			SENSOR_DS18B20_SetPinInput(DS18B20_PORT, DS18B20_PIN); // 输入
		}
	}
}
/* 读流程 */
uint8_t SENSOR_DS18B20_Read (void)
{
	uint8_t value = 0;
	SENSOR_DS18B20_SetPinOutput(DS18B20_PORT, DS18B20_PIN);
	for (int i=0;i<8;i++)
	{
		SENSOR_DS18B20_SetPinOutput(DS18B20_PORT, DS18B20_PIN);

		HAL_GPIO_WritePin(DS18B20_PORT, DS18B20_PIN, 0);  // 拉低
		delay_us(2);  // 拉低电平等待时间

		SENSOR_DS18B20_SetPinInput(DS18B20_PORT, DS18B20_PIN);
		if (HAL_GPIO_ReadPin (DS18B20_PORT, DS18B20_PIN))  
		{
			value |= 1<<i;  
		}
		delay_us (60);  // DS18B20数据响应时间
	}
	return value;
}

/* 计算CRC码 */
uint8_t SENSOR_DS18B20_CRC8(uint8_t *dats, uint8_t len) 
{
    uint8_t i, dat, crc, fb, st_byt;
    st_byt = 0;
    crc = 0;
    do {
      dat = dats[st_byt];
      for (i = 0; i < 8; i++) 
			{  
					fb = crc ^ dat;
					fb &= 1;
					crc >>= 1;
					dat >>= 1;
					if (fb == 1) 
						crc ^= 0x8c; 
       }
      st_byt++;
    } while (st_byt < len); 
    return crc;
}

/* 获取Serial Number&CRC&family Code */
SENSOR_DS18B20_SerialNumberInfo SENSOR_DS18B20_GetSN(void)
{
	SENSOR_DS18B20_SerialNumberInfo info;
	uint8_t recvs[8] = { 0 };
	
	SENSOR_DS18B20_Reset ();
	HAL_Delay (1);
	SENSOR_DS18B20_Write (0x33);  // read rom
	HAL_Delay (1);
	
	// 1 byte -> family code
	// 2 ~ 7 byte -> serial number
 //  8 byte -> CRC8	
	recvs[0] = SENSOR_DS18B20_Read(); // family code
	info.familyCode = recvs[0];
	
	for (int i = 0; i < 6; ++i) // serial number
	{ 
		recvs[i+1] = SENSOR_DS18B20_Read();
		info.sns[i] = recvs[i+1];
	}
	recvs[7] = SENSOR_DS18B20_Read(); // CRC8
	info.crc = recvs[7];
	if (SENSOR_DS18B20_CRC8(recvs, 7) != recvs[7]) // CRC8 检查
	{
		info.familyCode = 0;
		memset(info.sns, 0, sizeof(info.sns)/sizeof(uint8_t));
		info.crc = 0; 
		return info; // CRC校验不一致
	}
	return info;
}

/* 写Serial Number&CRC&family Code */
void SENSOR_DS18B20_WriteID(uint8_t index) 
{
	uint8_t id_data[8];
	id_data[0] = ds18b20_infos[index].familyCode;
	id_data[7] = ds18b20_infos[index].crc;
	for ( int i = 1; i < 7; ++i )
	{
		id_data[i] = ds18b20_infos[index].sns[i-1];
	}
	
	SENSOR_DS18B20_Reset (); 
	SENSOR_DS18B20_Write (0x55);  // skip ROM; //Match ROM [55h]
	for ( int i = 0; i < 8; i++ )
	{
		SENSOR_DS18B20_Write(id_data[i]);
	}
}

/* 等待电平被拉高 */
void SENSOR_DS18B20_WaitForHigh(uint32_t time) 
{
	SENSOR_DS18B20_SetPinInput(DS18B20_PORT, DS18B20_PIN);
	delay_us(time);
	while(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_9) == 0);
	SENSOR_DS18B20_SetPinOutput(DS18B20_PORT, DS18B20_PIN);
}

/* 将读取值转化成温度值 */
float SENSOR_DS18B20_ValueToTemperature(uint8_t lsb, uint8_t msb)
{
	uint16_t temp = 0;
	temp = (msb << 8) + lsb;
	
	if((temp&0xf800)==0xf800) // 符号位判定是否负数
	{
		temp=(~temp)+1; // 补码转原码
		return temp*(-0.0625); //12bit 增量值
	}
	else
	{
		return temp*0.0625;	//12bit 增量值
	}
}


/* 通过serial number数据获取温度 */
float SENSOR_DS18B20_GetTemperatureByID(uint8_t ds18b20_index)
{
	uint8_t recv_data[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0 }; // 9 Bytes
	uint8_t ds18b20_num = sizeof(ds18b20_infos) / sizeof(SENSOR_DS18B20_SerialNumberInfo);
	uint16_t temp = 0;
	if ( ds18b20_index >= ds18b20_num )
		return 0; // 不存在此设备
	
	SENSOR_DS18B20_Reset ();
	HAL_Delay (1);
	SENSOR_DS18B20_WriteID(ds18b20_index);
	SENSOR_DS18B20_Write(0x44);//Convert Temperature [44h]
	
	SENSOR_DS18B20_WaitForHigh(20);
	SENSOR_DS18B20_Reset ();
	SENSOR_DS18B20_WriteID(ds18b20_index);
	SENSOR_DS18B20_Write(0xBE);//Read Scratchpad [BEh]
	
	
	for (uint8_t i = 0; i < 9; i++)
	{
		recv_data[i] = SENSOR_DS18B20_Read();
	}
	
	return SENSOR_DS18B20_ValueToTemperature(recv_data[0], recv_data[1]);
}

代码

无需下载, 代码上面基本都提供了

Note:

支持你的DS18B20, 你需要修改，改成你的DS18B20的信息

SENSOR_DS18B20_SerialNumberInfo ds18b20_infos[] =

{

{ 0x28, { 0x2E, 0x7C, 0x04, 0x05, 0x00, 0x00 }, 0xCC },

{ 0x28, { 0x2F, 0x7D, 0x10, 0x02, 0x01, 0x00 }, 0xBE }

};