簡介
- 這TM的是個超級坑的通訊過程，雖然符合SPI通訊流程，但要是你直接用SPI通訊會發現完全不是這麼回事。這個是在STM32F0系列單片機上使用的範例，可以正常讀取溫度和溼度，只寫了主機模式。
- database.h 裏面沒啥東西，可以直接用
#include "stm32f0xx.h"代替
代碼
SHT2x.h
#ifndef SHT2x_H
#define SHT2x_H
//---------- Includes ----------------------------------------------------------
#include "I2C_HAL.h"
#include "database.h"
//---------- Defines -----------------------------------------------------------
typedef union {
uint16_t u16; // element specifier for accessing whole u16
int16_t i16; // element specifier for accessing whole i16
struct {
#ifdef LITTLE_ENDIAN // Byte-order is little endian
uint8_t u8L; // element specifier for accessing low u8
uint8_t u8H; // element specifier for accessing high u8
#else // Byte-order is big endian
uint8_t u8H; // element specifier for accessing low u8
uint8_t u8L; // element specifier for accessing high u8
#endif
} s16; // element spec. for acc. struct with low or high u8
} nt16;
// Error codes
typedef enum{
ACK_ERROR = 0x01,
TIME_OUT_ERROR = 0x02,
CHECKSUM_ERROR = 0x04,
UNIT_ERROR = 0x08
}etError;
// CRC
#define SHT2xPOLYNOMIAL 0x131 //P(x)=x^8+x^5+x^4+1 = 100110001
// sensor command
typedef enum{
TRIG_T_MEASUREMENT_HM = 0xE3, // command trig. temp meas. hold master
TRIG_RH_MEASUREMENT_HM = 0xE5, // command trig. humidity meas. hold master
TRIG_T_MEASUREMENT_POLL = 0xF3, // command trig. temp meas. no hold master
TRIG_RH_MEASUREMENT_POLL = 0xF5, // command trig. humidity meas. no hold master
USER_REG_W = 0xE6, // command writing user register
USER_REG_R = 0xE7, // command reading user register
SOFT_RESET = 0xFE // command soft reset
}etSHT2xCommand;
typedef enum {
SHT2x_RES_12_14BIT = 0x00, // RH=12bit, T=14bit
SHT2x_RES_8_12BIT = 0x01, // RH= 8bit, T=12bit
SHT2x_RES_10_13BIT = 0x80, // RH=10bit, T=13bit
SHT2x_RES_11_11BIT = 0x81, // RH=11bit, T=11bit
SHT2x_RES_MASK = 0x81 // Mask for res. bits (7,0) in user reg.
} etSHT2xResolution;
typedef enum {
SHT2x_EOB_ON = 0x40, // end of battery
SHT2x_EOB_MASK = 0x40, // Mask for EOB bit(6) in user reg.
} etSHT2xEob;
typedef enum {
SHT2x_HEATER_ON = 0x04, // heater on
SHT2x_HEATER_OFF = 0x00, // heater off
SHT2x_HEATER_MASK = 0x04, // Mask for Heater bit(2) in user reg.
} etSHT2xHeater;
// measurement signal selection
typedef enum{
HUMIDITY,
TEMP
}etSHT2xMeasureType;
typedef enum{
I2C_ADR_W = 128, // sensor I2C address + write bit
I2C_ADR_R = 129 // sensor I2C address + read bit
}etI2cHeader;
uint8_t SHT2x_MeasureHM(etSHT2xMeasureType eSHT2xMeasureType, nt16 *pMeasurand);
float SHT2x_CalcRH(uint16_t u16sRH);
float SHT2x_CalcTemperatureC(uint16_t u16sT);
void SHT2x_Process();
#endif
SHT2x.c
//==============================================================================
// SH2x 溫溼度採集程序
//==============================================================================
// File : SHT2x.c
// Author : MC
// Compiler : Keil 5
//==============================================================================
//---------- Includes ----------------------------------------------------------
#include "SHT2x.h"
#include <assert.h> // assert functions
/*
校驗
data 校驗的數據
nbrOfBytes 數據長度
checksum 校驗對比數
返回 0 成功 CHECKSUM_ERROR 4 失敗
*/
//==============================================================================
uint8_t SHT2x_CheckCrc(uint8_t data[], uint8_t nbrOfBytes, uint8_t checksum)
//==============================================================================
{
uint8_t crc = 0;
uint8_t byteCtr;
//calculates 8-Bit checksum with given polynomial
for (byteCtr = 0; byteCtr < nbrOfBytes; ++byteCtr)
{ crc ^= (data[byteCtr]);
for (uint8_t bit = 8; bit > 0; --bit)
{ if (crc & 0x80) crc = (crc << 1) ^ SHT2xPOLYNOMIAL;
else crc = (crc << 1);
}
}
if (crc != checksum) return CHECKSUM_ERROR;
else return 0;
}
/*
主機模式採集溫度或適度
eSHT2xMeasureType 需要採集的項， HUMIDITY溼度 TEMP溫度
pMeasurand 採集回來的原始值
*/
//===========================================================================
uint8_t SHT2x_MeasureHM(etSHT2xMeasureType eSHT2xMeasureType, nt16 *pMeasurand)
//===========================================================================
{
uint8_t checksum; //checksum
uint8_t data[2]; //data array for checksum verification
uint8_t error=0; //error variable
uint16_t i; //counting variable
//-- write I2C sensor address and command --
I2c_StartCondition();
error |= I2c_WriteByte (I2C_ADR_W); // I2C Adr
IIC_Wait_Ack();
switch(eSHT2xMeasureType)
{ case HUMIDITY: I2c_WriteByte(TRIG_RH_MEASUREMENT_HM); break;
case TEMP : I2c_WriteByte(TRIG_T_MEASUREMENT_HM); break;
default: assert(0);
}
IIC_Wait_Ack();
I2c_StartCondition();
I2c_WriteByte (I2C_ADR_R);
IIC_Wait_Ack();
//-- read two data bytes and one checksum byte --
pMeasurand->s16.u8H = data[0] = I2c_SHT21WithSCLReadByte(ACK);
pMeasurand->s16.u8L = data[1] = I2c_ReadByte(ACK);
checksum=I2c_ReadByte(NO_ACK);
// //-- verify checksum --
error |= SHT2x_CheckCrc (data,2,checksum);
I2c_StopCondition();
return error;
}
/*
原始值轉換爲溼度
u16sRH 原始值
返回 溼度
*/
//==============================================================================
float SHT2x_CalcRH(uint16_t u16sRH)
//==============================================================================
{
float humidityRH; // variable for result
u16sRH &= ~0x0003; // clear bits [1..0] (status bits)
//-- calculate relative humidity [%RH] --
humidityRH = -6.0 + 125.0/65536 * (float)u16sRH; // RH= -6 + 125 * SRH/2^16
return humidityRH;
}
/*
原始值轉換爲溫度
u16sRH 原始值
返回 溫度
*/
//==============================================================================
float SHT2x_CalcTemperatureC(uint16_t u16sT)
//==============================================================================
{
float temperatureC; // variable for result
u16sT &= ~0x0003; // clear bits [1..0] (status bits)
//-- calculate temperature --
temperatureC= -46.85 + 175.72/65536 *(float)u16sT; //T= -46.85 + 175.72 * ST/2^16
return temperatureC;
}
/*
用戶線程
*/
nt16 sRH={0}; //variable for raw humidity ticks
nt16 sT={0}; //variable for raw temperature ticks
void SHT2x_Process(){
// --- measure humidity with "Hold Master Mode (HM)" ---
SHT2x_MeasureHM(HUMIDITY, &sRH);
}
I2C_HAL.h
#ifndef I2C_HAL_H
#define I2C_HAL_H
//---------- Includes ----------------------------------------------------------
#include "database.h"
//---------- Defines -----------------------------------------------------------
//IO口操作宏定義
#define GPIOSCL GPIOA
#define PinSCL GPIO_Pin_2
#define GPIOSDA GPIOA
#define PinSDA GPIO_Pin_3
//IO方向設置
#define SDA_IN() {GPIOA->MODER&=0XFFFFFF3F;}
#define SDA_OUT() {uint32_t Temp=GPIOA->MODER;\
Temp&=0XFFFFFF3F;\
Temp|=0x00000040;\
GPIOA->MODER=Temp;}
#define SCL_IN() {GPIOA->MODER&=0XFFFFFFCF;}
#define SCL_OUT() {uint32_t Temp=GPIOA->MODER;\
Temp&=0XFFFFFFCF;\
Temp|=0x00000010;\
GPIOA->MODER=Temp;}
//IO操作函數
#define IIC_SCL1 GPIO_SetBits(GPIOSCL,PinSCL)
#define IIC_SCL0 GPIO_ResetBits(GPIOSCL,PinSCL) //SCL
#define IIC_SDAx(x) GPIO_WriteBit(GPIOSDA,PinSDA,x)
#define IIC_SDA1 GPIO_SetBits(GPIOSDA,PinSDA) //SDA
#define IIC_SDA0 GPIO_ResetBits(GPIOSDA,PinSDA) //SDA
#define READ_SDA GPIO_ReadInputDataBit(GPIOSDA,PinSDA) //輸入SDA
#define READ_SCL GPIO_ReadInputDataBit(GPIOSDA,PinSCL) //輸入SCL
//---------- Enumerations ------------------------------------------------------
// I2C level
typedef enum{
LOW = 0,
HIGH = 1,
}etI2cLevel;
// I2C acknowledge
typedef enum{
ACK = 0,
NO_ACK = 1,
}etI2cAck;
//==============================================================================
void I2c_Init ();
//==============================================================================
//Initializes the ports for I2C interface
//==============================================================================
void I2c_StartCondition ();
//==============================================================================
// writes a start condition on I2C-bus
// input : -
// output: -
// return: -
// note : timing (delay) may have to be changed for different microcontroller
// _____
// SDA: |_____
// _______
// SCL : |___
//==============================================================================
void I2c_StopCondition ();
//==============================================================================
// writes a stop condition on I2C-bus
// input : -
// output: -
// return: -
// note : timing (delay) may have to be changed for different microcontroller
// _____
// SDA: _____|
// _______
// SCL : ___|
//===========================================================================
uint8_t I2c_WriteByte (uint8_t txByte);
//===========================================================================
// writes a byte to I2C-bus and checks acknowledge
// input: txByte transmit byte
// output: -
// return: error
// note: timing (delay) may have to be changed for different microcontroller
//===========================================================================
uint8_t I2c_ReadByte (etI2cAck ack);
//===========================================================================
// reads a byte on I2C-bus
// input: rxByte receive byte
// output: rxByte
// note: timing (delay) may have to be changed for different microcontroller
u8 IIC_Wait_Ack(void);
uint8_t I2c_SHT21WithSCLReadByte(etI2cAck ack);
#endif
I2C_HAL.c
//---------- Includes ----------------------------------------------------------
#include "I2C_HAL.h"
//==============================================================================
void I2c_Init ()
//==============================================================================
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA , ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2|GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
IIC_SDA0; // Set port as output for configuration
IIC_SCL0; // Set port as output for configuration
SDA_OUT(); // Set SDA level as low for output mode
SCL_OUT();
IIC_SDA1; // I2C-bus idle mode SDA released (input)
IIC_SCL1; // I2C-bus idle mode SCL released (input)
}
//==============================================================================
void I2c_StartCondition ()
//==============================================================================
{
SDA_OUT();
SCL_OUT();
IIC_SDA1;
IIC_SCL1;
delay_us(20); // hold time start condition (t_HD;STA)
IIC_SDA0;
delay_us(20); // hold time start condition (t_HD;STA)
IIC_SCL0;
delay_us(20);
}
//==============================================================================
void I2c_StopCondition ()
//==============================================================================
{
SDA_OUT();
SCL_OUT();
IIC_SDA0;
IIC_SCL0;
delay_us(20); // set-up time stop condition (t_SU;STO)
IIC_SCL1;
delay_us(20); // set-up time stop condition (t_SU;STO)
IIC_SDA1;
delay_us(20);
}
//不產生ACK應答
void IIC_NAck(void)
{
SCL_OUT();
SDA_OUT();
IIC_SCL0;
IIC_SDA1;
delay_us(10);
IIC_SCL1;
delay_us(10);
IIC_SCL0;
}
//產生ACK應答
void IIC_Ack(void)
{
SCL_OUT();
SDA_OUT();
IIC_SCL0;
IIC_SDA0;
delay_us(10);
IIC_SCL1;
delay_us(10);
IIC_SCL0;
}
//等待應答信號到來
//返回值：1，接收應答失敗
// 0，接收應答成功
u8 IIC_Wait_Ack(void)
{
u8 ucErrTime=0;
SDA_IN(); //SDA設置爲輸入
IIC_SCL1;delay_us(5);
while(READ_SDA)
{
ucErrTime++;
if(ucErrTime>250)
{
I2c_StopCondition();
return 1;
}
delay_us(100);
}
IIC_SCL0;//時鐘輸出0
return 0;
}
//==============================================================================
uint8_t I2c_WriteByte (uint8_t txByte)
//==============================================================================
{
uint8_t mask,error=0;
u8 t;
SCL_OUT();
SDA_OUT();
IIC_SCL0;//拉低時鐘開始數據傳輸
for(t=0;t<8;t++)
{
IIC_SDAx((txByte&0x80)>>7);
txByte<<=1;
delay_us(10); //對TEA5767這三個延時都是必須的
IIC_SCL1;
delay_us(10);
IIC_SCL0;
delay_us(10);
}
return error; //return error code
}
//==============================================================================
uint8_t I2c_ReadByte (etI2cAck ack)
//==============================================================================
{
unsigned char i,receive=0;
SCL_OUT();
SDA_IN();//SDA設置爲輸入
for(i=0;i<8;i++ )
{
IIC_SCL0;
delay_us(5);
IIC_SCL1;
receive<<=1;
if(READ_SDA)receive++;
delay_us(5);
}
if (ack==ACK)
IIC_Ack(); //發送ACK
else
IIC_NAck();//發送nACK
return receive;
}
//==============================================================================
uint8_t I2c_SHT21WithSCLReadByte(etI2cAck ack)
//==============================================================================
{
uint16_t i;
unsigned char receive=0;
SCL_IN(); // set SCL I/O port as input
SDA_IN();
for(i=0; i<10000; i++) // wait until master hold is released or
{ delay_us(10); // a timeout (~1s) is reached
if (READ_SCL==1){
if(READ_SDA)receive++;
break;
}
}
SCL_OUT();
SDA_IN();//SDA設置爲輸入
for(i=0;i<7;i++ )
{
IIC_SCL0;
delay_us(5);
IIC_SCL1;
receive<<=1;
if(READ_SDA)receive++;
delay_us(5);
}
if (ack==ACK)
IIC_Ack(); //發送ACK
else
IIC_NAck();//發送nACK
return receive;
}