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利用鸿蒙系统实现温湿度传感器的数据读取与显示

发布时间:2023-12-03 15:02:55 202


      今天主要和大家聊一聊,如何使用鸿蒙系统去提取AHT20的温湿度传感器的数值,该传感器采用ADC位数为20Bit,具有体积小,精度高和成本低的优点。

利用鸿蒙系统实现温湿度传感器的数据读取与显示_初始化

第一:温湿度传感器基本参数

利用鸿蒙系统实现温湿度传感器的数据读取与显示_初始化_02

管脚定义与参考电路

利用鸿蒙系统实现温湿度传感器的数据读取与显示_初始化_03

利用鸿蒙系统实现温湿度传感器的数据读取与显示_单片机_04

I2C时序特性----支持标准100Hz,高速400KHz

利用鸿蒙系统实现温湿度传感器的数据读取与显示_#include_05

利用鸿蒙系统实现温湿度传感器的数据读取与显示_#define_06

第二:温度代码具体实现

     上面分析了,温湿度传感器的基本实现原理与方法,主要精力可以放在代码的具体实现上。

#include "aht20.h"

#include
#include
#include

#include "wifiiot_i2c.h"
#include "wifiiot_errno.h"

#define AHT20_I2C_IDX WIFI_IOT_I2C_IDX_0

#define AHT20_STARTUP_TIME 20*1000 // 上电启动时间
#define AHT20_CALIBRATION_TIME 40*1000 // 初始化(校准)时间
#define AHT20_MEASURE_TIME 75*1000 // 测量时间

#define AHT20_DEVICE_ADDR 0x38
#define AHT20_READ_ADDR ((0x38<<1)|0x1)
#define AHT20_WRITE_ADDR ((0x38<<1)|0x0)

#define AHT20_CMD_CALIBRATION 0xBE // 初始化(校准)命令
#define AHT20_CMD_CALIBRATION_ARG0 0x08
#define AHT20_CMD_CALIBRATION_ARG1 0x00

/**
* 传感器在采集时需要时间,主机发出测量指令(0xAC)后,延时75毫秒以上再读取转换后的数据并判断返回的状态位是否正常。
* 若状态比特位[Bit7]为0代表数据可正常读取,为1时传感器为忙状态,主机需要等待数据处理完成。
**/
#define AHT20_CMD_TRIGGER 0xAC // 触发测量命令
#define AHT20_CMD_TRIGGER_ARG0 0x33
#define AHT20_CMD_TRIGGER_ARG1 0x00

// 用于在无需关闭和再次打开电源的情况下,重新启动传感器系统,软复位所需时间不超过20 毫秒
#define AHT20_CMD_RESET 0xBA // 软复位命令

#define AHT20_CMD_STATUS 0x71 // 获取状态命令

/**
* STATUS 命令回复:
* 1. 初始化后触发测量之前,STATUS 只回复 1B 状态值;
* 2. 触发测量之后,STATUS 回复6B:1B 状态值 + 2B 湿度 + 4b湿度 + 4b温度 + 2B 温度
* RH = Srh / 2^20 * 100%
* T = St / 2^20 * 200 - 50
**/
#define AHT20_STATUS_BUSY_SHIFT 7 // bit[7] Busy indication
#define AHT20_STATUS_BUSY_MASK (0x1<#define AHT20_STATUS_BUSY(status) ((status & AHT20_STATUS_BUSY_MASK) >> AHT20_STATUS_BUSY_SHIFT)

#define AHT20_STATUS_MODE_SHIFT 5 // bit[6:5] Mode Status
#define AHT20_STATUS_MODE_MASK (0x3<#define AHT20_STATUS_MODE(status) ((status & AHT20_STATUS_MODE_MASK) >> AHT20_STATUS_MODE_SHIFT)

// bit[4] Reserved
#define AHT20_STATUS_CALI_SHIFT 3 // bit[3] CAL Enable
#define AHT20_STATUS_CALI_MASK (0x1<#define AHT20_STATUS_CALI(status) ((status & AHT20_STATUS_CALI_MASK) >> AHT20_STATUS_CALI_SHIFT)
// bit[2:0] Reserved

#define AHT20_STATUS_RESPONSE_MAX 6

#define AHT20_RESOLUTION (1<<20) // 2^20

#define AHT20_MAX_RETRY 10

static uint32_t AHT20_Read(uint8_t* buffer, uint32_t buffLen)
{
WifiIotI2cData data = { 0 };
data.receiveBuf = buffer;
data.receiveLen = buffLen;
uint32_t retval = I2cRead(AHT20_I2C_IDX, AHT20_READ_ADDR, &data);
if (retval != WIFI_IOT_SUCCESS) {
printf("I2cRead() failed, %0X!\n", retval);
return retval;
}
return WIFI_IOT_SUCCESS;
}

static uint32_t AHT20_Write(uint8_t* buffer, uint32_t buffLen)
{
WifiIotI2cData data = { 0 };
data.sendBuf = buffer;
data.sendLen = buffLen;
uint32_t retval = I2cWrite(AHT20_I2C_IDX, AHT20_WRITE_ADDR, &data);
if (retval != WIFI_IOT_SUCCESS) {
printf("I2cWrite(%02X) failed, %0X!\n", buffer[0], retval);
return retval;
}
return WIFI_IOT_SUCCESS;
}

// 发送获取状态命令
static uint32_t AHT20_StatusCommand(void)
{
uint8_t statusCmd[] = { AHT20_CMD_STATUS };
return AHT20_Write(statusCmd, sizeof(statusCmd));
}

// 发送软复位命令
static uint32_t AHT20_ResetCommand(void)
{
uint8_t resetCmd[] = {AHT20_CMD_RESET};
return AHT20_Write(resetCmd, sizeof(resetCmd));
}

// 发送初始化校准命令
static uint32_t AHT20_CalibrateCommand(void)
{
uint8_t clibrateCmd[] = {AHT20_CMD_CALIBRATION, AHT20_CMD_CALIBRATION_ARG0, AHT20_CMD_CALIBRATION_ARG1};
return AHT20_Write(clibrateCmd, sizeof(clibrateCmd));
}

// 读取温湿度值之前, 首先要看状态字的校准使能位Bit[3]是否为 1(通过发送0x71可以获取一个字节的状态字),
// 如果不为1,要发送0xBE命令(初始化),此命令参数有两个字节, 第一个字节为0x08,第二个字节为0x00。
uint32_t AHT20_Calibrate(void)
{
uint32_t retval = 0;
uint8_t buffer[AHT20_STATUS_RESPONSE_MAX];
memset(&buffer, 0x0, sizeof(buffer));

retval = AHT20_StatusCommand();
if (retval != WIFI_IOT_SUCCESS) {
return retval;
}

retval = AHT20_Read(buffer, sizeof(buffer));
if (retval != WIFI_IOT_SUCCESS) {
return retval;
}

if (AHT20_STATUS_BUSY(buffer[0]) || !AHT20_STATUS_CALI(buffer[0])) {
retval = AHT20_ResetCommand();
if (retval != WIFI_IOT_SUCCESS) {
return retval;
}
usleep(AHT20_STARTUP_TIME);
retval = AHT20_CalibrateCommand();
usleep(AHT20_CALIBRATION_TIME);
return retval;
}

return WIFI_IOT_SUCCESS;
}

// 发送 触发测量 命令,开始测量
uint32_t AHT20_StartMeasure(void)
{
uint8_t triggerCmd[] = {AHT20_CMD_TRIGGER, AHT20_CMD_TRIGGER_ARG0, AHT20_CMD_TRIGGER_ARG1};
return AHT20_Write(triggerCmd, sizeof(triggerCmd));
}

// 接收测量结果,拼接转换为标准值
uint32_t AHT20_GetMeasureResult(float* temp, float* humi)
{
uint32_t retval = 0, i = 0;
if (temp == NULL || humi == NULL) {
return WIFI_IOT_FAILURE;
}

uint8_t buffer[AHT20_STATUS_RESPONSE_MAX];
memset(&buffer, 0x0, sizeof(buffer));
retval = AHT20_Read(buffer, sizeof(buffer)); // recv status command result
if (retval != WIFI_IOT_SUCCESS) {
return retval;
}

for (i = 0; AHT20_STATUS_BUSY(buffer[0]) && i < AHT20_MAX_RETRY; i++) {
// printf("AHT20 device busy, retry %d/%d!\r\n", i, AHT20_MAX_RETRY);
usleep(AHT20_MEASURE_TIME);
retval = AHT20_Read(buffer, sizeof(buffer)); // recv status command result
if (retval != WIFI_IOT_SUCCESS) {
return retval;
}
}
if (i >= AHT20_MAX_RETRY) {
printf("AHT20 device always busy!\r\n");
return WIFI_IOT_FAILURE;
}

uint32_t humiRaw = buffer[1];
humiRaw = (humiRaw << 8) | buffer[2];
humiRaw = (humiRaw << 4) | ((buffer[3] & 0xF0) >> 4);
*humi = humiRaw / (float)AHT20_RESOLUTION * 100;

uint32_t tempRaw = buffer[3] & 0x0F;
tempRaw = (tempRaw << 8) | buffer[4];
tempRaw = (tempRaw << 8) | buffer[5];
*temp = tempRaw / (float)AHT20_RESOLUTION * 200 - 50;
// printf("humi = %05X, %f, temp= %05X, %f\r\n", humiRaw, *humi, tempRaw, *temp);
return WIFI_IOT_SUCCESS;
}

接下来,可以利用鸿蒙系统对温湿度传感器里面的温度数据进行读取,然后再将获取到的温湿度数据进行显示输出。

#include "aht20.h"

#include
#include

#include "ohos_init.h"
#include "cmsis_os2.h"
#include "wifiiot_gpio.h"
#include "wifiiot_gpio_ex.h"
#include "wifiiot_i2c.h"

void Aht20TestTask(void* arg)
{
(void) arg;
uint32_t retval = 0;

IoSetFunc(WIFI_IOT_IO_NAME_GPIO_13, WIFI_IOT_IO_FUNC_GPIO_13_I2C0_SDA);
IoSetFunc(WIFI_IOT_IO_NAME_GPIO_14, WIFI_IOT_IO_FUNC_GPIO_14_I2C0_SCL);

I2cInit(WIFI_IOT_I2C_IDX_0, 400*1000);

retval = AHT20_Calibrate();
printf("AHT20_Calibrate: %d\r\n", retval);

while (1) {
float temp = 0.0, humi = 0.0;

retval = AHT20_StartMeasure();
printf("AHT20_StartMeasure: %d\r\n", retval);

retval = AHT20_GetMeasureResult(&temp, &humi);
printf("AHT20_GetMeasureResult: %d, temp = %.2f, humi = %.2f\r\n", retval, temp, humi);

sleep(1);
}
}

void Aht20Test(void)
{
osThreadAttr_t attr;

attr.name = "Aht20Task";
attr.attr_bits = 0U;
attr.cb_mem = NULL;
attr.cb_size = 0U;
attr.stack_mem = NULL;
attr.stack_size = 4096;
attr.priority = osPriorityNormal;

if (osThreadNew(Aht20TestTask, NULL, &attr) == NULL) {
printf("[Aht20Test] Failed to create Aht20TestTask!\n");
}
}
APP_FEATURE_INIT(Aht20Test);

     具体的操作实现如下视频所示。


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