AHT20+BMP280模塊簡介
本品采用了數(shù)字溫濕度傳感器AHT20與數(shù)字氣壓傳感器BPM280 組成, I2C 輸出。電壓直流3.3V供電(兩個模塊電源是一起的,板子沒有穩(wěn)壓器件,BMP280最高支持電壓3.6V,所以這里建議是3.3V供電),體積小巧,方便集成。板子是將兩個器件的IIC接到一起了,==板載4.7K的上拉電阻==。
AHT20
AHT20 是一款高精度數(shù)字式溫濕度傳感器,采用 I2C 通信接口,集成度高、功耗極低,能同時精準測量環(huán)境溫度(-40℃ - 85℃)和相對濕度(0%~100% RH),輸出數(shù)據(jù)穩(wěn)定可靠,無需額外校準,廣泛應用于智能家居、氣象監(jiān)測、消費電子等對溫濕度檢測精度和功耗有嚴格要求的場景。AHT20測溫誤差±0.3℃,濕度誤差±2%。
器件IIC地址0x38(7位)
器件讀取流程說明:
1.上電后要等待40ms,讀取溫濕度值之前, 首先要看狀態(tài)字的校準使能位Bit[3]是否為 1(通
過發(fā)送0x71可以獲取一個字節(jié)的狀態(tài)字),如果不為1,要發(fā)送0xBE命令(初始化),此命令參數(shù)
有兩個字節(jié), 第一個字節(jié)為0x08,第二個字節(jié)為0x00。
2.直接發(fā)送 0xAC命令(觸發(fā)測量),此命令參數(shù)有兩個字節(jié),第一個字節(jié)為 0x33,第二個字節(jié)
為0x00。
3.等待75ms待測量完成,忙狀態(tài)Bit[7]為0,然后可以讀取六個字節(jié)(發(fā)0X71即可以讀取)。
4.計算溫濕度值。
讀取溫濕度數(shù)據(jù)流程圖
溫濕度數(shù)據(jù)都是分別20bit,輸出數(shù)據(jù)后需要對數(shù)據(jù)進行轉(zhuǎn)換,下面是對應的轉(zhuǎn)換公式:
BMP280
寄存器相關說明直接查閱這篇文章: [STM32軟件SPI驅(qū)動BMP280(OLED顯示)],這里就不再贅述。上面文章通訊使用的是SPI,這里說下BMP280傳感器 IIC通訊。
BMP280主要參數(shù):
- 大氣壓強 :300-1100hPa,相對精度±0.12hPa
- 溫度 :-40-85℃,絕對精度±0.5℃(由內(nèi)部溫度傳感器測量的溫度。此溫度值取決于印刷電路板的溫度、傳感器元件自身的發(fā)熱情況以及環(huán)境溫度,通常會高于環(huán)境溫度)
- IIC地址 :該 7 位設備地址為 111011x。前 6 位為固定位。最后一位可通過 SDO 值進行更改,并且在運行過程中可以進行更改。將 SDO 連接到 GND 從機地址為 1110110(0x76);將其連接到 Vddio 則從機地址為 1110111(0x77)板子設計吧SDO引腳拉高了,所以這里BMP280的器件地址是0x77(7位)。
寄存器

IIC寫時序
IIC讀時序
測試接線
| AHT20+BMP280 | STM32F103C8T6 | 1.44LCD ST7735 |
|---|---|---|
| VDD | 3.3v | 3.3V |
| GND | GND | G |
| SCL | PB10 | -- |
| SDA | PB11 | -- |
| -- | PA8 | BLK |
| -- | PB1 | DC |
| -- | PB14 | RST |
| -- | PB12 | CS |
| -- | PB13 | SCL |
| -- | PB14 | MOSI |
串口輸出使用的是串口1,接線用USB轉(zhuǎn)TTL接到單片機串口上,接線分別是VCC接3.3V,GND接GND,TX接PA10,RX接PA9。這里使用的單片機是直接把串口1接到板載的usb口了,所以就沒有單獨外接TTL模塊了。
代碼
AHT20.c
#include "stm32f10x.h" // Device header
#include "AHT20.h"
#include "MyI2C.h"
#include "Delay.h"
#define AHT20_ADDRESS 0x38 //AHT20的I2C從機地址
#define AHT20_SoftReset 0xBA
//1讀0寫
/**
* 函 數(shù):AHT20寫寄存器
* 參 數(shù):RegAddress 寄存器地址,范圍:參考AHT20手冊的寄存器描述
* 參 數(shù):Data 要寫入寄存器的數(shù)據(jù),范圍:0x00~0xFF
* 返 回 值:無
*/
void AHT20_WriteSingleReg(uint8_t Data)
{
MyI2C_Start(); //I2C起始
MyI2C_SendByte(AHT20_ADDRESS < < 1| 0x00); //發(fā)送從機地址,讀寫位為0,表示即將寫入,0x70
MyI2C_ReceiveAck(); //接收應答
MyI2C_SendByte(Data); //發(fā)送要寫入寄存器的數(shù)據(jù)
MyI2C_ReceiveAck(); //接收應答
MyI2C_Stop(); //I2C終止
}
//AHT20讀單個寄存器
uint8_t AHT20_ReadSingleReg()
{
uint8_t Data;
MyI2C_Start(); //I2C重復起始
MyI2C_SendByte(AHT20_ADDRESS < < 1| 0x01); //發(fā)送從機地址,讀寫位為1,表示即將讀取,0x71
MyI2C_ReceiveAck(); //接收應答
Data = MyI2C_ReceiveByte(); //接收指定寄存器的數(shù)據(jù)
MyI2C_SendAck(1); //發(fā)送應答,給從機非應答,終止從機的數(shù)據(jù)輸出
MyI2C_Stop(); //I2C終止
return Data;
}
//AHT20軟復位
void AHT20_SoftRes(void)
{
AHT20_WriteSingleReg(AHT20_SoftReset);
}
//讀取AHT20的狀態(tài)寄存器
uint8_t AHT20_Read_Status(void)
{
uint8_t Byte_first;
Byte_first = AHT20_ReadSingleReg();
return Byte_first;
}
//查詢cal enable位有沒有使能?
uint8_t AHT20_Read_Cal_Enable(void)
{
uint8_t val = 0;//ret = 0,
val = AHT20_Read_Status();
if((val & 0x68)==0x08) //判斷NOR模式和校準輸出是否有效 0110 1000
return 1;
else return 0;
}
//向AHT20發(fā)送AC觸發(fā)測量命令
void AHT20_SendAC(void)
{
MyI2C_Start();
MyI2C_SendByte(AHT20_ADDRESS < 1 |0x00); //寫
MyI2C_ReceiveAck();
MyI2C_SendByte(0xac); //發(fā)送AC命令
MyI2C_ReceiveAck();
MyI2C_SendByte(0x33);
MyI2C_ReceiveAck();
MyI2C_SendByte(0x00);
MyI2C_ReceiveAck();
MyI2C_Stop();
}
//讀取AHT20的溫度和濕度數(shù)據(jù)
void AHT20_Read_CTdata(uint32_t *ct)
{
volatile uint8_t Byte_1th=0;
volatile uint8_t Byte_2th=0;
volatile uint8_t Byte_3th=0;
volatile uint8_t Byte_4th=0;
volatile uint8_t Byte_5th=0;
volatile uint8_t Byte_6th=0;
uint32_t RetuData = 0;
uint16_t cnt = 0;
AHT20_SendAC();//向AHT20發(fā)送AC命令
Delay_ms(75);//等待75ms
cnt = 0;
while(((AHT20_Read_Status()&0x80)==0x80))//等待忙狀態(tài)結(jié)束
{
Delay_us(1508);
if(cnt++ >=100)
{
break;
}
}
MyI2C_Start();
MyI2C_SendByte(AHT20_ADDRESS < 1 | 0x01);//0x70+1 0x70為設備地址 1為方向位
MyI2C_ReceiveAck();
Byte_1th = MyI2C_ReceiveByte();//狀態(tài)字
MyI2C_SendAck(0);
Byte_2th = MyI2C_ReceiveByte();//濕度字節(jié)
MyI2C_SendAck(0);
Byte_3th = MyI2C_ReceiveByte();//濕度字節(jié)
MyI2C_SendAck(0);
Byte_4th = MyI2C_ReceiveByte();//高4位為濕度 低4位為溫度
MyI2C_SendAck(0);
Byte_5th = MyI2C_ReceiveByte();//溫度字節(jié)
MyI2C_SendAck(0);
Byte_6th = MyI2C_ReceiveByte();//溫度字節(jié)
MyI2C_SendAck(1);
MyI2C_Stop();
RetuData = (RetuData|Byte_2th)< 8;
RetuData = (RetuData|Byte_3th)< 8;
RetuData = (RetuData|Byte_4th);
RetuData =RetuData > >4;
ct[0] = RetuData;
RetuData = 0;
RetuData = (RetuData|Byte_4th)< 8;
RetuData = (RetuData|Byte_5th)< 8;
RetuData = (RetuData|Byte_6th);
RetuData = RetuData&0xfffff;
ct[1] =RetuData;
}
void AHT20_SyetemInit(void)
{
MyI2C_Start();
MyI2C_SendByte(AHT20_ADDRESS < < 1| 0x00);
MyI2C_ReceiveAck();
MyI2C_SendByte(0x08);
MyI2C_ReceiveAck();
MyI2C_SendByte(0x00);
MyI2C_ReceiveAck();
MyI2C_Stop();
}
/**
* 函 數(shù):AHT20初始化
* 參 數(shù):無
* 返 回 值:無
*/
uint8_t AHT20_Init(void) //初始化AHT20
{
int count;
MyI2C_Init();
Delay_us(11038);
AHT20_SyetemInit();
Delay_ms(500);//延時0.5S
while(AHT20_Read_Cal_Enable()==0)//需要等待狀態(tài)字status的Bit[3]=1時才去讀數(shù)據(jù)。如果Bit[3]不等于1 ,發(fā)軟件復位0xBA給AHT20,再重新初始化AHT20,直至Bit[3]=1
{
AHT20_SoftRes(); //軟復位AHT20
Delay_us(11038);
AHT20_SyetemInit();
count++;
if(count >=10)return 0;
Delay_ms(500);
}
return 1;
}
BMP280.c
#include "stm32f10x.h" // Device header
#include "BMP280_Reg.h"
#include "BMP280.h"
#include "MyI2C.h"
#include "Delay.h"
#define BMP280_ADDRESS 0x77 //從設備地址
#define BMP280_RESET_VALUE 0xB6 //復位寄存器寫入值
uint16_t Dig_T1;
int16_t Dig_T2;
int16_t Dig_T3;
uint16_t Dig_P1;
int16_t Dig_P2;
int16_t Dig_P3;
int16_t Dig_P4;
int16_t Dig_P5;
int16_t Dig_P6;
int16_t Dig_P7;
int16_t Dig_P8;
int16_t Dig_P9;
/**
* 函 數(shù):BMP280寫寄存器
* 參 數(shù):RegAddress 寄存器地址
* 參 數(shù):Data 要寫入寄存器的數(shù)據(jù),范圍:0x00~0xFF
* 返 回 值:無
*/
void BMP280_WriteReg(uint8_t RegAddress, uint8_t Data)
{
MyI2C_Start(); //I2C起始
MyI2C_SendByte(BMP280_ADDRESS < 1|0x00); //發(fā)送從機地址,讀寫位為0,表示即將寫入
MyI2C_ReceiveAck(); //接收應答
MyI2C_SendByte(RegAddress); //發(fā)送寄存器地址
MyI2C_ReceiveAck(); //接收應答
MyI2C_SendByte(Data); //發(fā)送要寫入寄存器的數(shù)據(jù)
MyI2C_ReceiveAck(); //接收應答
MyI2C_Stop(); //I2C終止
}
/**
* 函 數(shù):BMP280讀寄存器
* 參 數(shù):RegAddress 寄存器地址
* 返 回 值:讀取寄存器的數(shù)據(jù),范圍:0x00~0xFF
*/
uint8_t BMP280_ReadReg(uint8_t RegAddress)
{
uint8_t Data;
MyI2C_Start(); //I2C起始
MyI2C_SendByte(BMP280_ADDRESS < 1|0x00); //發(fā)送從機地址,讀寫位為0,表示即將寫入
MyI2C_ReceiveAck(); //接收應答
MyI2C_SendByte(RegAddress); //發(fā)送寄存器地址
MyI2C_ReceiveAck(); //接收應答
MyI2C_Start(); //I2C重復起始
MyI2C_SendByte(BMP280_ADDRESS < 1|0x01); //發(fā)送從機地址,讀寫位為1,表示即將讀取
MyI2C_ReceiveAck(); //接收應答
Data = MyI2C_ReceiveByte(); //接收指定寄存器的數(shù)據(jù)
MyI2C_SendAck(1); //發(fā)送應答,給從機非應答,終止從機的數(shù)據(jù)輸出
MyI2C_Stop(); //I2C終止
return Data;
}
/**
* 函 數(shù):BMP280讀ID
* 參 數(shù):無
* 返 回 值:BMP280的ID號
*/
uint8_t BMP280_ReadID(void)
{
return BMP280_ReadReg(BMP280_CHIPID_REG);
}
/**
* 函 數(shù):讀取轉(zhuǎn)換3個連續(xù)寄存器
* 參 數(shù):首個讀取的寄存器
* 返 回 值:合并后的總值
*/
long bmp280_MultipleReadThree(unsigned char addr)
{
unsigned char msb, lsb, xlsb;
long temp = 0;
msb = BMP280_ReadReg(addr);
lsb = BMP280_ReadReg(addr + 1);
xlsb = BMP280_ReadReg(addr + 2);
temp = (long)(((unsigned long)msb < < 12)|((unsigned long)lsb < < 4)|((unsigned long)xlsb > > 4));
return temp;
}
/**
* 函 數(shù):讀取轉(zhuǎn)換2個連續(xù)寄存器
* 參 數(shù):首個讀取的寄存器
* 返 回 值:合并后的總值
*/
short bmp280_MultipleReadTwo(unsigned char addr)
{
unsigned char msb, lsb;
short temp = 0;
lsb = BMP280_ReadReg(addr);
msb = BMP280_ReadReg(addr + 1);
temp = (short)msb < < 8;
temp |= (short)lsb;
return temp;
}
/**
* 函 數(shù):BMP280初始化
* 參 數(shù):無
* 返 回 值:無
*/
void BMP280_Init(void)
{
MyI2C_Init(); //先初始化底層的I2C
uint8_t Osrs_T = 1; //Temperature oversampling x 1
uint8_t Osrs_P = 4; //Pressure oversampling x 1
uint8_t Mode = 3; //Normal mode
uint8_t T_sb= 5; //Tstandby 1000ms 測量速率1HZ
uint8_t Filter = 0; //Filter off
uint8_t Spi3w_en = 0; //3-wire SPI Disable
uint8_t Ctrl_Meas_Reg = (Osrs_T < < 5) | (Osrs_P < < 2) | Mode;
uint8_t Config_Reg = (T_sb < < 5) | (Filter < < 2) | Spi3w_en;
//狀態(tài)全部清零
BMP280_WriteReg(BMP280_RESET_REG, BMP280_RESET_VALUE); //將對應的配置值寫入寄存器
BMP280_WriteReg(BMP280_CTRLMEAS_REG, Ctrl_Meas_Reg);
BMP280_WriteReg(BMP280_CONFIG_REG, Config_Reg);
Dig_T1 = bmp280_MultipleReadTwo(BMP280_DIG_T1_LSB_REG);
Dig_T2 = bmp280_MultipleReadTwo(BMP280_DIG_T2_LSB_REG);
Dig_T3 = bmp280_MultipleReadTwo(BMP280_DIG_T3_LSB_REG);
Dig_P1 = bmp280_MultipleReadTwo(BMP280_DIG_P1_LSB_REG);
Dig_P2 = bmp280_MultipleReadTwo(BMP280_DIG_P2_LSB_REG);
Dig_P3 = bmp280_MultipleReadTwo(BMP280_DIG_P3_LSB_REG);
Dig_P4 = bmp280_MultipleReadTwo(BMP280_DIG_P4_LSB_REG);
Dig_P5 = bmp280_MultipleReadTwo(BMP280_DIG_P5_LSB_REG);
Dig_P6 = bmp280_MultipleReadTwo(BMP280_DIG_P6_LSB_REG);
Dig_P7 = bmp280_MultipleReadTwo(BMP280_DIG_P7_LSB_REG);
Dig_P8 = bmp280_MultipleReadTwo(BMP280_DIG_P8_LSB_REG);
Dig_P9 = bmp280_MultipleReadTwo(BMP280_DIG_P9_LSB_REG);
Delay_ms(200);
}
#define BMP280_S32_t long signed int
#define BMP280_U32_t long unsigned int
#define BMP280_S64_t long long signed int
BMP280_S32_t t_fine;
/**
* 函 數(shù):BMP280獲取溫度值
* 參 數(shù):無
* 返 回 值:溫度值
*/
int32_t BMP280_GetTemp(void)
{
BMP280_S32_t var1, var2, T;
BMP280_S32_t adc_T;
adc_T = bmp280_MultipleReadThree(BMP280_TEMPERATURE_MSB_REG);
//Temperature
var1 = ((((adc_T >>3) - ((BMP280_S32_t)Dig_T1< 1))) * ((BMP280_S32_t)Dig_T2)) > > 11;
var2 = (((((adc_T >>4) - ((BMP280_S32_t)Dig_T1)) * ((adc_T >>4) - ((BMP280_S32_t)Dig_T1))) > > 12) *
((BMP280_S32_t)Dig_T3)) > > 14;
t_fine = var1 + var2;
T = (t_fine * 5 + 128) > > 8;
return T;
}
/**
* 函 數(shù):BMP280獲取壓力值
* 參 數(shù):無
* 返 回 值:壓力值
*/
uint32_t BMP280_GetPress(void)
{
BMP280_S64_t var1, var2, p;
BMP280_S32_t adc_P;
adc_P = bmp280_MultipleReadThree(BMP280_PRESSURE_MSB_REG);
var1 = ((BMP280_S64_t)t_fine) - 128000;
var2 = var1 * var1 * (BMP280_S64_t)Dig_P6;
var2 = var2 + ((var1*(BMP280_S64_t)Dig_P5)< 17);
var2 = var2 + (((BMP280_S64_t)Dig_P4)< 35);
var1 = ((var1 * var1 * (BMP280_S64_t)Dig_P3) >>8) + ((var1 * (BMP280_S64_t)Dig_P2)< 12);
var1 = (((((BMP280_S64_t)1)< 47)+var1))*((BMP280_S64_t)Dig_P1) >>33;
if (var1 == 0)
{
return 0; // avoid exception caused by division by zero
}
p = 1048576-adc_P;
p = (((p< 31)-var2)*3125)/var1;
var1 = (((BMP280_S64_t)Dig_P9) * (p >>13) * (p >>13)) > > 25;
var2 = (((BMP280_S64_t)Dig_P8) * p) > > 19;
p = ((p + var1 + var2) > > 8) + (((BMP280_S64_t)Dig_P7)< 4);
return (BMP280_U32_t)p;
}
main.c
#include "stm32f10x.h"
#include "Delay.h"
#include "AHT20.h"
#include "uart.h"
#include "stdio.h"
#include "BMP280.h"
#include "lcd_init.h"
#include "lcd.h"
int main(void)
{
int c1,t1;
uint32_t CT_data[2];
uint8_t ID;
float BMP_Pressure,BMP_Temperature;
/*模塊初始化*/
uart_init(9600);
BMP280_Init();
LCD_Init();//LCD初始化
LCD_Fill(0,0,LCD_W,LCD_H,WHITE);
while(1)
{
while(AHT20_Read_Cal_Enable()==0)//等到校準輸出使能位為1,才讀取。
{
AHT20_Init();//如果為0再使能一次
Delay_ms(30);
}
AHT20_Read_CTdata(CT_data); //讀取溫度和濕度,可間隔1.5S讀一次
c1 = CT_data[0] * 1000 / 1024 / 1024; //計算得到濕度值(放大了10倍,如果c1=523,表示現(xiàn)在濕度為52.3%)
t1 = CT_data[1] * 200 * 10 / 1024 / 1024 - 500;//計算得到溫度值(放大了10倍,如果t1=245,表示現(xiàn)在溫度為24.5℃)
printf("****************************************************n");
printf("AHT20溫濕度傳感器測試數(shù)據(jù):n");
printf("溫度: %d.%d ℃ n", t1/10, t1%10);
printf("濕度: %d.%d %% n", c1/10, c1%10);
printf("n");
ID = BMP280_ReadID();
BMP_Temperature = BMP280_GetTemp();
BMP_Pressure = BMP280_GetPress();
printf("BMP280傳感器測試數(shù)據(jù): n");
printf("ID:0x%xn",ID);
printf("溫度: %0.2f ℃ n",BMP_Temperature/100.0);
printf("氣壓: %0.4f hPa n",BMP_Pressure / 25600.0);
printf("nn");
LCD_ShowString(18,0,"AHT20+BMP280",BLACK,WHITE,16,0);
LCD_ShowString(50,16,"TEST",BLACK,WHITE,16,0);
//AHT20數(shù)據(jù)顯示
LCD_ShowString(0,32,"AHT20",BLACK,WHITE,16,0);
//AHT20溫度
LCD_ShowChinese(0,48,"溫度",BLACK,WHITE,16,0);
LCD_ShowString(32,48,":",BLACK,WHITE,16,0);
LCD_ShowIntNum(40,48,t1/10,2,BLACK,WHITE,16);
LCD_ShowString(56,48,".",BLACK,WHITE,16,0);
LCD_ShowIntNum(64,48,t1%10,1,BLACK,WHITE,16);
LCD_ShowChinese(80,48,"℃",BLACK,WHITE,16,0);
//AHT20濕度
LCD_ShowChinese(0,64,"濕度",BLACK,WHITE,16,0);
LCD_ShowString(32,64,":",BLACK,WHITE,16,0);
LCD_ShowIntNum(40,64,c1/10,2,BLACK,WHITE,16);
LCD_ShowString(56,64,".",BLACK,WHITE,16,0);
LCD_ShowIntNum(64,64,c1%10,1,BLACK,WHITE,16);
LCD_ShowString(80,64,"%",BLACK,WHITE,16,0);
//BMP280數(shù)據(jù)顯示
LCD_ShowString(0,80,"BMP280",BLACK,WHITE,16,0);
//BMP280溫度
LCD_ShowChinese(0,96,"溫度",BLACK,WHITE,16,0);
LCD_ShowString(32,96,":",BLACK,WHITE,16,0);
LCD_ShowFloatNum1(40,96,BMP_Temperature/100.0,4,BLACK,WHITE,16);
LCD_ShowChinese(80,96,"℃",BLACK,WHITE,16,0);
//BMP280大氣壓強
LCD_ShowChinese(0,112,"氣壓",BLACK,WHITE,16,0);
LCD_ShowString(32,112,":",BLACK,WHITE,16,0);
LCD_ShowIntNum(40,112,BMP_Pressure / 25600,4,BLACK,WHITE,16);
LCD_ShowString(72,112,"hPa",BLACK,WHITE,16,0);
Delay_ms(1000);
}
}
現(xiàn)象
LCD顯示:
串口輸出
總結(jié)
需要代碼的可以在評論區(qū)留言郵箱哦!!!
審核編輯 黃宇
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