RT-Thread-NK-980IOT I2C测试：读取BMP180RT-Thread问答社区

NK-980IOT I2C测试：读取BMP180

发布于 2022-03-29 18:24:01 浏览：851 订阅该版

[tocm]

## 开发环境
* 软件：RT-Thread Studio
* 硬件：NK-980IOT开发板

## I2C介绍
I2C是一种双线、双向串行总线，为设备之间的数据交换提供了一种简单有效的方法。I2C标准是一种真正的多主总线，包括冲突检测和仲裁，当两个或多个主总线试图同时控制总线时，可防止数据损坏。

共有四套I2C控制器，支持断电唤醒功能。

### 特性
I2C总线使用两根导线（SDA和SCL）在连接到总线的设备之间传输信息。I2C总线的主要功能包括：

* 最多支持三个I2C端口
* 主/从模式
* 主设备和从设备之间的双向数据传输
* 多主机模式（无中心主机）
* 支持标准模式（100kbps）、快速模式（400kbps）和快速模式plus（1Mbps）
* 在不损坏总线上串行数据的情况下，同时传输主机之间的仲裁
* 内置14位超时计数器，在I2C总线挂起且定时器超时计数器溢出时请求I2C中断
* 可编程时钟允许多种速率控制
* 支持7位寻址和10位寻址模式
* 支持多地址识别（带掩码选项的四个从地址）
* 支持断电唤醒功能
* 支持设置/保持时间可编程

### 功能框图
![h9Eu9Ahwg1-pPqL60k0yK8krG3uzHoA9li7p6UfQrj4.png](https://oss-club.rt-thread.org/uploads/20220329/3faf08b9b2afdd56eba7c2cea200b42b.png)

### 基本配置
在测试用使用的I2C2，下面主要介绍I2C2的配置。

时钟源配置：在I2CKEN中启用I2C2外设时钟（CLK\_APBCLK1\[2\]）

复位配置：在I2C2RST中重置I2C2控制器（SYS\_APBIPRST1\[2\]）

管脚配置：

![be0sgar0jsCGnBrKwMmBWT6uDqL36ArFGzZWSdOdBG8.png](https://oss-club.rt-thread.org/uploads/20220329/70373cecfb3f2b70ee99d2f11a339b93.png)

测试中使用的是PB5/PB7:
![e0uUvCZENhosHCddy2M2CHsUGVaJJcHa1wbJuDs8fyU.png](https://oss-club.rt-thread.org/uploads/20220329/f1f28a5c356e725c55a2cd136c053d87.png)

### 功能描述
在I2C总线上，数据在主设备和从设备之间传输。SCL和SDA线路上的数据位以字节为单位同步传输。每个数据字节的长度为8位。每个数据位有一个SCL时钟脉冲，MSB先传输，每个传输的字节后有一个确认位。在SCL的高位期间对每个位进行采样；因此，SDA线可能仅在SCL的低期发生变化，并且在SCL的高期必须保持稳定。当SCL处于高位时，SDA线上的转换被解释为命令（启动或停止）。有关I2C总线定时的更多详细信息，请参考图6.16-2。

#### I2C时序图
![K03cuIiHCPU25pUYteu0Gw3X48Fk_KRN8bq4Gjncyo0.png](https://oss-club.rt-thread.org/uploads/20220329/2f30b207e65743c1f76074802ee960b1.png)

以上内容均来自芯片的数据手册，数据手册里内容非常全，建议大家在需要时一定要去翻阅。新唐是国产IC里少有的能把手册做那么全的，很给力。

## 外部电路
测试使用了GY-68模块，模块原理图：
![bQAQ6ShEISC2ZyrWJ8iCeIdxvuYvZLQh67_jSw6uf54.jpg](https://oss-club.rt-thread.org/uploads/20220329/942ecc91b030e06db41977dc086cb135.jpg)

与开发板的连接
![DmOgflbAA0mLPZIUJbuzOO64RJynzaRSqfL4SoYno7Q.jpg](https://oss-club.rt-thread.org/uploads/20220329/a6965bf0aa828833907bd471b8d5b16e.jpg.webp)

## 工程代码部分
### 工程配置
先使能I2C2
![ZiscGJI6dj9xO5b9eairg5Uc1LXtV4a1GsigdMWh2VA.png](https://oss-club.rt-thread.org/uploads/20220329/eae53f5e7741f57e52f5187583da80ef.png)

在软件包里有传感器驱动库可以使用
![lqvholZFZZ5_OQDajmuIWIKYnFrXj5DCcFqhpHl4F3g.png](https://oss-club.rt-thread.org/uploads/20220329/9613ec57a9c148cd8a62049d6d252512.png)

这个库写的不错，里面有对设备抽象、添加自己的设备等代码，对提高编程能力很有启发和学习价值。

### 初始化
```Plain Text
int rt_hw_bmp180_init(const char *name, struct rt_sensor_config *cfg)
{
  	rt_err_t ret = RT_EOK;
	rt_sensor_t sensor_baro = RT_NULL, sensor_temp = RT_NULL;
    struct rt_sensor_module *module = RT_NULL;
	struct bmp180_dev 		*bmp180 = RT_NULL;
    uint8_t bmbuf[22] = {0};
	
	bmp180 = rt_calloc(1, sizeof(struct bmp180_dev));
	if(bmp180 == RT_NULL)
	{
	  	LOG_E("malloc memory failed\r\n");
		ret = -RT_ERROR;
		goto __exit;
	}
	
    bmp180->i2c_bus = rt_i2c_bus_device_find(cfg->intf.dev_name);
    if(bmp180->i2c_bus == RT_NULL)
    {
        LOG_E("i2c bus device %s not found!\r\n", cfg->intf.dev_name);
		ret = -RT_ERROR;
		goto __exit;
    }	
	
	module = rt_calloc(1, sizeof(struct rt_sensor_device));
    if(module == RT_NULL)
	{
	  	LOG_E("malloc memory failed\r\n");
	  	ret = -RT_ERROR;
		goto __exit;
	}
	module->sen[0] = sensor_baro;
    module->sen[1] = sensor_temp;
    module->sen_num = 2;
	
	/*  barometric pressure sensor register */
    {
        sensor_baro = rt_calloc(1, sizeof(struct rt_sensor_device));
        if (sensor_baro == RT_NULL)
		{
		  	goto __exit;
		}
		rt_memset(sensor_baro, 0x0, sizeof(struct rt_sensor_device));
        sensor_baro->info.type       = RT_SENSOR_CLASS_BARO;
        sensor_baro->info.vendor     = RT_SENSOR_VENDOR_BOSCH;
        sensor_baro->info.model      = "bmp180_baro";
        sensor_baro->info.unit       = RT_SENSOR_UNIT_PA;
        sensor_baro->info.intf_type  = RT_SENSOR_INTF_I2C;
        sensor_baro->info.range_max  = 110000;	/* 1Pa */
        sensor_baro->info.range_min  = 30000;
        sensor_baro->info.period_min = 100;	/* read ten times in 1 second */

rt_memcpy(&sensor_baro->config, cfg, sizeof(struct rt_sensor_config));
        sensor_baro->ops = &bmp180_ops;
        sensor_baro->module = module;
        
        ret = rt_hw_sensor_register(sensor_baro, name, RT_DEVICE_FLAG_RDWR, (void*)bmp180);
        if (ret != RT_EOK)
        {
            LOG_E("device register err code: %d", ret);
            goto __exit;
        }
    }
    /* temperature sensor register */
    {
        sensor_temp = rt_calloc(1, sizeof(struct rt_sensor_device));
        if (sensor_temp == RT_NULL)
		{
			goto __exit;
		}
		rt_memset(sensor_temp, 0x0, sizeof(struct rt_sensor_device));
        sensor_temp->info.type       = RT_SENSOR_CLASS_TEMP;
        sensor_temp->info.vendor     = RT_SENSOR_VENDOR_BOSCH;
        sensor_temp->info.model      = "bmp180_temp";
        sensor_temp->info.unit       = RT_SENSOR_UNIT_DCELSIUS;
        sensor_temp->info.intf_type  = RT_SENSOR_INTF_I2C;
        sensor_baro->info.range_max  = 850;	/* 0.1C */
        sensor_baro->info.range_min  = -400;
        sensor_temp->info.period_min = 100;	/* read ten times in 1 second */

rt_memcpy(&sensor_temp->config, cfg, sizeof(struct rt_sensor_config));
        sensor_temp->ops = &bmp180_ops;
        sensor_temp->module = module;
        
        ret = rt_hw_sensor_register(sensor_temp, name, RT_DEVICE_FLAG_RDWR, (void*)bmp180);
        if (ret != RT_EOK)
        {
            LOG_E("device register err code: %d", ret);
            goto __exit;
        }
    }
   
	/* bmp180 read calc param */
	ret = bmp180_read_regs(sensor_baro, BMS_CAL_AC1, bmbuf, 22);
	if(ret == RT_EOK)
	{
		bmp180->calc_param.ac1 = (bmbuf[0]<<8)|bmbuf[1];
		bmp180->calc_param.ac2 = (bmbuf[2]<<8)|bmbuf[3];
		bmp180->calc_param.ac3 = (bmbuf[4]<<8)|bmbuf[5];
		bmp180->calc_param.ac4 = (bmbuf[6]<<8)|bmbuf[7];
		bmp180->calc_param.ac5 = (bmbuf[8]<<8)|bmbuf[9];
		bmp180->calc_param.ac6 = (bmbuf[10]<<8)|bmbuf[11];
		bmp180->calc_param.b1 = (bmbuf[12]<<8)|bmbuf[13];
		bmp180->calc_param.b2 = (bmbuf[14]<<8)|bmbuf[15];
		bmp180->calc_param.mb = (bmbuf[16]<<8)|bmbuf[17];
		bmp180->calc_param.mc = (bmbuf[18]<<8)|bmbuf[19];
		bmp180->calc_param.md = (bmbuf[20]<<8)|bmbuf[21];
	}
	else
	{
		LOG_E("bmp180 read calc param failed\r\n");
		goto __exit;
	}
    return RT_EOK;

__exit:
  	if(sensor_baro)
	{
		rt_free(sensor_baro);
	}
	
	if(sensor_temp)
	{
		rt_free(sensor_temp);
	}
	
    if(module)
	{
	 	rt_free(module);
	}
	
	if (bmp180)
	{
		rt_free(bmp180);
	}
    return ret;
}
```

### 功能实现
```Plain Text
static void read_baro_entry(void *parameter)
{
    rt_device_t baro_dev = RT_NULL, temp_dev = RT_NULL;
    struct rt_sensor_data baro_data,temp_data;
    rt_size_t res0 = 0, res1 = 1;
	rt_uint8_t chip_id;
	
    baro_dev = rt_device_find("baro_bmp180");
    if (baro_dev == RT_NULL)
    {
	  	 rt_kprintf("not found baro_bmp180 device\r\n");
        return;
    }

if (rt_device_open(baro_dev, RT_DEVICE_FLAG_RDONLY) != RT_EOK)
    {
        rt_kprintf("open baro_180 failed\r\n");
        return;
    }

temp_dev = rt_device_find("temp_bmp180");
    if (temp_dev == RT_NULL)
    {
	  	 rt_kprintf("not found temp_bmp180 device\r\n");
        return;
    }

if (rt_device_open(temp_dev, RT_DEVICE_FLAG_RDONLY) != RT_EOK)
    {
        rt_kprintf("open temp_bmp180 failed\r\n");
        return;
    }
	
	rt_device_control(baro_dev, RT_SENSOR_CTRL_SET_ODR, (void *)(1));/* 1Hz read */
    rt_device_control(temp_dev, RT_SENSOR_CTRL_SET_ODR, (void *)(1));/* 1Hz read */
	
	rt_device_control(temp_dev, RT_SENSOR_CTRL_GET_ID, (void*)&chip_id);
	rt_kprintf("bmp180 chip ID [0x%X]\n", chip_id);
	while (1)
    {
        res0 = rt_device_read(baro_dev, 0, &baro_data, 1);
		res0 = rt_device_read(temp_dev, 0, &temp_data, 1);
        if (res0==0 || res1==0)
        {
            rt_kprintf("read data failed! result is %d,%d\n", res0, res1);
            rt_device_close(baro_dev);
			rt_device_close(temp_dev);
            return;
        }
        else
        {
        	rt_kprintf("baro[%dPa],temp[%d.%dC],timestamp[%d]\r\n", baro_data.data.baro, 
					   temp_data.data.temp/10, temp_data.data.temp%10,
					   temp_data.timestamp);
        }

rt_thread_delay(500);
    }
}
```

### 工程代码连接
https://gitee.com/sunxh_rk/nk-980-iot-i2c

## 测试结果
![chRZDonZ-_s8qmsLSta8ZwsOJIGiIeSkPKqCr9TZeFo.jpg](https://oss-club.rt-thread.org/uploads/20220329/6d7af78d4964dba950733ec2d6208aaa.jpg.webp)

//视频
[演示视频.mp4](https://oss-club.rt-thread.org/uploads/20220329/7f1f533f5cba8559e08b5fa32e70b85b.mp4)

## 总结
RT-THREAD现在支持的开发板和传感器越来越全了，点一点就能完成工程搭建和测试。非常适合快速出产品的项目开发。
新唐的NK-980IOT开发板除了开始上手时不熟悉烧写过程，其他都很容易使用，提供的手册资料非常全，堪比ti、adi等大厂，遇到问题建议大家多翻翻手册。