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1# Niobe407开发板OpenHarmony基于HDF驱动框架编程开发——I2C
2
3I2C是一种串行，同步，半双工通信协议，允许在同一总线上同时存在多个主机和从机。I2C总线由两条线组成：串行数据线（SDA）和串行时钟（SCL）。两条线都需要上拉电阻。I2C组件为设备提供读写等操作。
4
5本示例将演示如何在Niobe407开发板上通过HDF驱动框架，使用I2C3接口对RJGT102芯片进行读写芯片UUID操作。
6
7## 接口说明
8
9```
101. I2C open打开I2C函数:DevHandle I2cOpen(int16_t number);
11    参数说明:
12        number:  I2C控制器ID
13        return:  返回NULL,表示初始化成功
14
152. I2C close打开I2C函数:void I2cClose(DevHandle handle);
16
173. I2C transfer启动到I2C设备的自定义传输函数:int32_t I2cTransfer(DevHandle handle, struct I2cMsg *msgs, int16_t count);
18    参数说明:
19        handle:  指向通过{@link I2cOpen} 获得的I2C 控制器的设备句柄的指针
20        msgs:    指示指向 I2C 传输消息结构体数组的指针
21        count:   表示消息结构数组的长度
22        return:  返回传输的消息结构数，表示成功，返回负数，表示失败
23```
24
25## 编译调试
26- 进入//kernel/liteos_m目录, 在menuconfig配置中进入如下选项:
27
28     `(Top) → Platform → Board Selection → select board niobe407 → use talkweb niobe407 application → niobe407 application choose`
29
30- 选择 `204_hdf_i2c`
31
32- 在menuconfig的`(Top) → Driver`选项中使能如下配置:
33
34```
35    [*] Enable Driver
36    [*]     HDF driver framework support
37    [*]         Enable HDF platform driver
38    [*]             Enable HDF platform uart driver
39```
40- 回到sdk根目录，执行`hb build -f`脚本进行编译。
41
42### 运行结果
43
44示例代码编译烧录代码后，按下开发板的RESET按键，通过串口助手查看日志
45```
46Entering scheduler
47[HDF:E/HDF_LOG_TAG]DeviceManagerStart in
48[HDF:I/devmgr_service]start svcmgr result 0
49[HDF:I/hcs_blob_if]CheckHcsBlobLength: the blobLength: 1248, byteAlign: 1
50[HDF:D/device_node]node HDF_PLATFORM_I2C_MANAGER property empty, match attr:
51[HDF:I/device_node]launch devnode HDF_PLATFORM_I2C_MANAGER
52[HDF:I/i2c_core]I2cManagerBind: Enter!
53[HDF:I/device_node]launch devnode HDF_PLATFORM_I2C_3
54[HDF:I/i2c_core]I2cCntlrAdd: use default lock methods!
55OHOS # hiview init success.
56
57<--------------- OHOS Application Start Here --------------->
58[HDF:E/HDF_LOG_TAG]into HdfI2cTestEntry!
59
60write uuid success: [11, 22, 33, 44, aa, bb, cc, dd]
61read uuid success: [11, 22, 33, 44, aa, bb, cc, dd]
62```
63## I2C HDF HCS配置文件解析
64- device_i2c_info.hcs文件位于/device/board/talkweb/niobe407/sdk/hdf_config/device_i2c_info.hcs,本例子使用的是i2c3
65```
66
67root {
68    module = "talkweb,stm32f407";
69    device_info {
70        match_attr = "hdf_manager";
71        template host {
72            hostName = "";
73            priority = 100;
74            template device {
75                template deviceNode {
76                    policy = 0;
77                    priority = 100;
78                    preload = 0;
79                    permission = 0664;
80                    moduleName = "";
81                    serviceName = "";
82                    deviceMatchAttr = "";
83                }
84            }
85        }
86        platform :: host {
87            hostName = "platform_host";
88            priority = 0;
89
90            device_i2c :: device {
91                i2c_manager :: deviceNode {
92                    policy = 2;
93                    priority = 50;
94                    moduleName = "HDF_PLATFORM_I2C_MANAGER";
95                    serviceName = "HDF_PLATFORM_I2C_MANAGER";
96                }
97
98                i2c3 :: deviceNode {
99                    policy = 0;
100                    priority = 100;
101                    preload = 0;
102                    permission = 0664;
103                    moduleName = "HDF_I2C";
104                    serviceName = "HDF_PLATFORM_I2C_3";
105                    deviceMatchAttr = "i2c3_config";
106                }
107            }
108        }
109    }
110}
111```
112
113- hdf_i2c.hcs文件位于/device/board/talkweb/niobe407/sdk/hdf_config/hdf_i2c.hcs,在此文件中配置串口对应的GPIO引脚信息，I2C配置信息
114```
115#include "device_i2c_info.hcs"
116root {
117    platform {
118        i2c_config {
119            i2c3 {
120                gpio{
121                    // 要配置的引脚个数，接下来的引脚名必须定义成gpio_num_1, gpio_num_2, gpio_num_3...
122                    gpio_num_max = 2; //配置的GPIO个数
123
124                    // port, pin, mode, speed, outputType, pull, alternate
125                    gpio_num_1 = [7, 7, 2, 3, 1, 0, 4]; //GPIO配置1
126                    gpio_num_2 = [7, 8, 2, 3, 1, 0, 4]; //GPIO配置2
127                }
128
129                driver : gpio {
130                    match_attr = "i2c3_config";
131                    port = 3;  // I2C端口号(1~3)
132                    dev_mode = 0; //0 = master, 1= slave
133                    dev_addr = 0;  //I2C 本机地址
134                    speed = 100000; //I2C速率
135                }
136            }
137        }
138    }
139}
140```
141
142## 关于I2C通讯测试芯片RJGT102
143
144    RJGT102芯片为一款标准I2C通讯的加密芯片。
145
146    这里将此芯片当成普通EEPROM使用，通过读写芯片内部UUID区域，以测试HDF I2C的基本收发功能。
147
148    具体芯片读写操作时序及寄存器信息，请自行参考数据手册
149