828F/applications/drv/drv_aht20.c

/*
 * Copyright (c) 2025, Your Name
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2025-12-27     Developer    First version for AHT20 on RT-Thread
 */

#include <rtthread.h>
#include <rtdevice.h>
#include <board.h>

#define DBG_TAG "sensor.aht20"
#define DBG_LVL DBG_LOG
#include <rtdbg.h>

/* AHT20 I2C 地址 */
#define AHT20_I2C_ADDR        0x38
/* 使用的 I2C 总线设备名 */
#define AHT20_I2C_BUS_NAME    "i2c2"   // 根据你的板子修改，如 "i2c2"

static struct rt_i2c_bus_device *i2c_bus = RT_NULL;

/**
 * 向 AHT20 发送命令
 */
static rt_err_t aht20_send_cmd(rt_uint8_t cmd, const rt_uint8_t *data, rt_size_t len)
{
    rt_uint8_t buf[3] = {cmd};
    if (len > 0)
    {
        rt_memcpy(&buf[1], data, len);
    }

    struct rt_i2c_msg msgs[1] = {
        {
            .addr  = AHT20_I2C_ADDR,
            .flags = RT_I2C_WR,
            .buf   = buf,
            .len   = 1 + len,
        }
    };

    if (rt_i2c_transfer(i2c_bus, msgs, 1) != 1)
    {
        LOG_E("I2C send command 0x%02X failed.", cmd);
        return -RT_ERROR;
    }
    return RT_EOK;
}

/**
 * 从 AHT20 读取数据
 */
static rt_err_t aht20_read_data(rt_uint8_t *buf, rt_size_t len)
{
    struct rt_i2c_msg msgs[1] = {
        {
            .addr  = AHT20_I2C_ADDR,
            .flags = RT_I2C_RD,
            .buf   = buf,
            .len   = len,
        }
    };

    if (rt_i2c_transfer(i2c_bus, msgs, 1) != 1)
    {
        LOG_E("I2C read data failed.");
        return -RT_ERROR;
    }
    return RT_EOK;
}

/**
 * 初始化 AHT20
 */
static rt_err_t aht20_init_sensor(void)
{
    rt_uint8_t status = 0;
    rt_uint8_t cmd_data[2] = {0x08, 0x00};

    /* 发送初始化命令 */
    if (aht20_send_cmd(0xBE, cmd_data, 2) != RT_EOK)
    {
        LOG_E("Failed to send init command.");
        return -RT_ERROR;
    }

    rt_thread_mdelay(20); // 等待初始化完成

    /* 读取状态字节（可选） */
    if (aht20_read_data(&status, 1) == RT_EOK)
    {
        LOG_D("AHT20 status: 0x%02X", status);
    }

    return RT_EOK;
}

/**
 * 触发一次温湿度测量
 */
static rt_err_t aht20_trigger_measure(void)
{
    rt_uint8_t cmd[2] = {0x33, 0x00};
    return aht20_send_cmd(0xAC, cmd, 2);
}

/**
 * 读取原始温湿度数据（6 字节）
 */
static rt_err_t aht20_fetch_raw(rt_uint8_t raw[6])
{
    return aht20_read_data(raw, 6);
}

/**
 * 解析原始数据为温度（0.1°C）和湿度（0.1%RH）
 */
static void aht20_parse_data(const rt_uint8_t raw[6], rt_int32_t *temp, rt_int32_t *humi)
{
    rt_uint32_t humi_raw = ((rt_uint32_t)raw[1] << 12) | ((rt_uint32_t)raw[2] << 4) | (raw[3] >> 4);
    rt_uint32_t temp_raw = ((rt_uint32_t)raw[3] & 0x0F) << 16 | ((rt_uint32_t)raw[4] << 8) | raw[5];

    *humi = (rt_int32_t)((humi_raw * 1000) / (1 << 20)); // 转换为 0.1%RH
    *temp = (rt_int32_t)((temp_raw * 2000) / (1 << 20) - 500); // 转换为 0.1°C（公式：T = (raw / 2^20) * 200 - 50）
}

/**
 * AHT20 读取线程
 */
static void aht20_thread_entry(void *parameter)
{
    rt_uint8_t raw_data[6];

    extern rt_int32_t sys_temperature;
    extern rt_int32_t sys_humidity;

    while (1)
    {
        if (aht20_trigger_measure() != RT_EOK)
        {
            LOG_E("Trigger measurement failed.");
            rt_thread_mdelay(2000);
            continue;
        }

        rt_thread_mdelay(80); // AHT20 典型转换时间 75ms

        if (aht20_fetch_raw(raw_data) != RT_EOK)
        {
            LOG_E("Fetch raw data failed.");
            rt_thread_mdelay(2000);
            continue;
        }

        /* 检查忙标志（bit7 of raw_data[0] 应为 0）*/
        if (raw_data[0] & 0x80)
        {
            LOG_W("AHT20 is busy, retrying...");
            rt_thread_mdelay(100);
            continue;
        }

        aht20_parse_data(raw_data, &sys_temperature, &sys_humidity);

        rt_thread_mdelay(5000); // 每 2 秒读取一次
    }
}

/**
 * AHT20 驱动初始化函数
 */
static int rt_hw_aht20_init(void)
{
    i2c_bus = rt_i2c_bus_device_find(AHT20_I2C_BUS_NAME);
    if (i2c_bus == RT_NULL)
    {
        LOG_E("Failed to find I2C bus: %s", AHT20_I2C_BUS_NAME);
        return -RT_ENOSYS;
    }

    LOG_I("Found I2C bus: %s", AHT20_I2C_BUS_NAME);

    if (aht20_init_sensor() != RT_EOK)
    {
        LOG_E("AHT20 sensor initialization failed!");
        return -RT_ERROR;
    }

    LOG_I("AHT20 initialized successfully.");

    /* 创建读取线程 */
    rt_thread_t tid = rt_thread_create("ahtX0",
                                       aht20_thread_entry,
                                       RT_NULL,
                                       512,
                                       RT_THREAD_PRIORITY_MAX - 2,
                                       10);
    if (tid != RT_NULL)
    {
        rt_thread_startup(tid);
    }
    else
    {
        LOG_E("Failed to create AHT20 thread.");
        return -RT_ERROR;
    }

    return RT_EOK;
}

/* 自动初始化 */
INIT_APP_EXPORT(rt_hw_aht20_init);