【XR806开发板试用】通过http请求从心知天气网获取天气预报信息

1. 开发环境搭建

本次评测开发环境搭建在windows11的WSL2的Ubuntu20.04中，关于windows安装WSL2可以参考文章: Windows下安装Linux(Ubuntu20.04)子系统（WSL）
(1) 在WSL的Ubuntu20.04下安装必要的工具的.

• 安装git:

sudo apt-get install git

• 安装gcc编译器套件:

sudo apt-get install build-essential

• 安装bear，该工具用来生成编译数据库文件：compile_commands.json，可以实现编辑代码时智能提示和代码跳转.

sudo apt-get install bear

• 安装ncurses库,使用make menuconfig配置工程时依赖该库.
  sudo apt-get install libncurses5-dev

(2)安装windows下必要的工具
我们编译的固件要通过串口烧录到XR806,由于WSL2下不能直接使用windows的串口，所以需要在windows下使用工具 usbipd共享串口给WSL2使用，可以参考文章：WSL2下的usb串口设备使用
此外，我们编辑和阅读代码使用vscode,关于vscode的C/C++环境配置可参考文章：vscode配置C/C++环境

(3)搭建XR806编译开发环境
可以参考：搭建基于FreeRTOS的XR806开发环境, 需要注意的是文章中提供的编译工具链gcc-arm-none-eabi-8-2019-q3-update下载链接无效，在终端中使用如下命令下载编译工具链：
wget https://armkeil.blob.core.windows.net/developer/Files/downloads/gnu-rm/8-2019q3/RC1.1/gcc-arm-none-eabi-8-2019-q3-update-linux.tar.bz2

2. 创建工程

创建工程可以参考: 新工程创建, 我们工程命名为wifi_sta,我们工程所在目录如下图：

我们在终端中进入工程跟目录，按如下步骤来配置工程和编译代码生成镜像:

# 复制默认配置文件到顶层目录（不切换工程可不要此步骤）
$ make PRJ=demo/wifi_sta defconfig
# 检查SDK 基础配置，如工程名、芯片型号、高频晶振、板级配置是否正确
$ make menuconfig
# 清理，切换工程时需要
$ make build_clean
# 编译代码并生成镜像文件，生成的镜像文件为“out/xr_system.img”
$ bear make build -j 12 

依次执行上述命令后，在工程根目录执行如下命令，使用vscode打开工程
code .
在vscode中打开工程目录后，敲击F1键，弹出如下选择项，我们选择C/C++:编辑配置(UI)

在编译器路径输入框中输入XR806交叉编译器完整路径，如下图所示:

在高级设置下的编译命令输入框中输入编译数据库文件compile_commands.json的路径，如下图所示：

3. 编辑工程代码

想要从心知天气网获取天气预报，首先需要注册该网站账号. 注册账号并登陆，打开获取天气预报相关的API文档页: 未来15天逐日天气预报和昨日天气 阅读该文档了解到获取未来3天天气预报的接口地址为:
https://api.seniverse.com/v3/weather/daily.json?key=your_api_key&location=beijing&language=zh-Hans&unit=c&start=-1&days=5
其中参数"your_api_key"是你获取天气预报信息的API密钥，该API密钥可以从心知天气网主页进入控制台页面，然后点击左侧的"免费版",即可看到自己的私钥，该私钥即为API 密钥,如下图所示:

接下来我们编写代码实现通过http请求从心知天气网获取未来3天的天气信息.

1. 首先在main.c中添加必要的头文件:

#include <stdio.h>
#include <string.h>
#include "kernel/os/os.h"
#include "net/wlan/wlan.h"
#include "net/wlan/wlan_defs.h"
#include "common/framework/net_ctrl.h"
#include "common/framework/platform_init.h"#include <errno.h>
#include "lwip/err.h"
#include "lwip/sockets.h"
#include "lwip/sys.h"
#include "lwip/inet.h"
#include "lwip/netdb.h"
#include "sys/select.h"#include "cjson/cJSON.h"

2. 然后定义关于天气信息的结构体类型:

/* 天气数据结构体 */
typedef struct tagWeather
{/* 实况天气数据 */char id[32];				//idchar name[32];				//地名char country[32];			//国家char path[32];				//完整地名路径char timezone[32];			//时区char timezone_offset[32];   //时差char text[32];				//天气预报文字char code[32];				//天气预报代码char temperature[32];   	//气温char last_update[32];		//最后一次更新的时间/* 今天、明天、后天天气数据 */char date[3][32];			//日期char text_day[3][64];	    //白天天气现象文字char code_day[3][32];		//白天天气现象代码char code_night[3][64]; 	//晚间天气现象代码char high[3][32];			//最高温char low[3][32];			//最低温char wind_direction[3][64]; //风向char wind_speed[3][32];  	//风速，单位km/h（当unit=c时）char wind_scale[3][32];  	//风力等级
} Weather_T;

3. 再定义通过http的GET请求方式获取天气预报的请求头部:

#define WEB_SERVER     "api.seniverse.com" // 天气预报网服务器地址
#define WEB_PORT       "80"                // 天气预报网服务器端口号
#define CONFIG_API_KEY "xxxxxxxxxxxxxx" // 你的API密钥,从心知天气网控制台页面获取
/* 获取天气预报信息的http请求头部 */
#define  GET_REQUEST_PACKAGE     \"GET https://api.seniverse.com/v3/weather/daily.json?key=" CONFIG_API_KEY "&location=%s&language=zh-Hans&unit=c\r\n\r\n"#define HTTPC_DEMO_THREAD_STACK_SIZE (8 * 1024) /* 任务栈大小 */

4. 定义WiFi的ssid和password:

char *sta_ssid = "xxxxxx";  // 你要连接的WiFi名
char *sta_psk = "xxxxxxxx"; // 你要连接的WiFi密码
char httpc_response_buf[2048]; //用于保存获取到的天气信息的原始数据
int write_idx = 0;  // 写数据到httpc_response_buf的数组下标
static OS_Thread_t httpc_demo_thread; // 获取天气的线程ID

5. 编写WiFi联网初始化函数:

void sta_start(void)
{/* switch to sta mode */net_switch_mode(WLAN_MODE_STA);#if STA_MODE_USE_WPA2_ONLY/* set ssid and password to wlan, only use WPA2 mode to connect AP. */wlan_sta_config((uint8_t *)sta_ssid, strlen(sta_ssid), (uint8_t *)sta_psk, 0);
#else/* set ssid and password to wlan, use WPA2|WPA3 compatible mode to connect AP. */wlan_sta_set((uint8_t *)sta_ssid, strlen(sta_ssid), (uint8_t *)sta_psk);
#endif/* start scan and connect to ap automatically */wlan_sta_enable();
}

6. 在mian函数中添加如下代码

int main(void)
{observer_base *net_ob;platform_init();/* create an observer to monitor the net work state */net_ob = sys_callback_observer_create(CTRL_MSG_TYPE_NETWORK,NET_CTRL_MSG_ALL,net_cb,NULL);if (net_ob == NULL) {return -1;}if (sys_ctrl_attach(net_ob) != 0) {return -1;}sta_start();return 0;
}

其中，函数sys_callback_observer_create创建一个事件监听器，当函数第1个参数CTRL_MSG_TYPE_NETWORK和第2个参数NET_CTRL_MSG_ALL所指定的事件发生时自动调用回调函数net_cb，此处表示所有的网络事件发生时均会调用回调函数net_cb，net_cb定义如下:

static void net_cb(uint32_t event, uint32_t data, void *arg)
{uint16_t type = EVENT_SUBTYPE(event);switch (type) {case NET_CTRL_MSG_NETWORK_UP: // WiFi sta连接AP成功并自动分配了ip地址{/* 打印本机的IP地址,网关，子网掩码 */struct netif *nif = wlan_netif_get(WLAN_MODE_STA);while (!NET_IS_IP4_VALID(nif)) {OS_MSleep(100);}printf("local ip: %s\n", ipaddr_ntoa(&nif->ip_addr));printf("gw: %s\n", ipaddr_ntoa(&nif->gw));printf("netmask: %s\n", ipaddr_ntoa(&nif->netmask));}/*创建线程，通过http请求获取天气预报信息*/if (!OS_ThreadIsValid(&httpc_demo_thread)) {OS_ThreadCreate(&httpc_demo_thread,"httpc_demo_thread",httpc_demo_fun,(void *)NULL,OS_THREAD_PRIO_APP,HTTPC_DEMO_THREAD_STACK_SIZE);}break;case NET_CTRL_MSG_NETWORK_DOWN: //WiFi连接断开事件break;default:break;}
}

httpc_demo_fun函数的定义如下:

static void httpc_demo_fun(void *arg)
{http_get_weather("beijing");// 获取天气预报信息结束后，删除本线程OS_ThreadDelete(&httpc_demo_thread);
}

其中http_get_weather函数的参数即为想要获取天气预报的城市的汉语拼音名，定义如下:

static void http_get_weather(char *city)
{int32_t ret;char request_head[sizeof(REQUEST) + 64];const struct addrinfo hints = {.ai_family = AF_INET,.ai_socktype = SOCK_STREAM,};struct addrinfo *res;struct in_addr *addr;int s, r;Weather_T weather_data = {0};bzero(httpc_response_buf, sizeof(httpc_response_buf));/* 通过服务器域名和端口获取服务器的IP地址相关信息 */ret = getaddrinfo(WEB_SERVER, WEB_PORT, &hints, &res);if (ret != 0 || res == NULL) {printf("DNS lookup failed ret=%d res=%p\n", ret, res);return;}// Note: inet_ntoa is non-reentrant, look at ipaddr_ntoa_r for "real" code */addr = &((struct sockaddr_in *)res->ai_addr)->sin_addr;printf("DNS lookup succeeded. IP=%s\n", inet_ntoa(*addr));/* 创建soocket */s = socket(res->ai_family, res->ai_socktype, 0);if(s < 0) {printf("... Failed to allocate socket.\n");freeaddrinfo(res);return;}printf("... allocated socket\n");/* 使用第1步获取的服务器IP地址连接服务器 */if(connect(s, res->ai_addr, res->ai_addrlen) != 0) {printf("... socket connect failed errno=%d\n", errno);close(s);freeaddrinfo(res);return;}printf("... connected\n");freeaddrinfo(res);/* 使用城市名生成完整的http的GET请求头部并发送到服务器*/snprintf(request_head, sizeof(request_head), GET_REQUEST_PACKAGE, city);if (write(s, request_head, strlen(request_head)) < 0) {printf("... socket send failed\n");close(s);return;}printf("... socket send success\n");/* 读取服务器返回的应答数据 *//* Read HTTP response */do {r = read(s, &httpc_response_buf[write_idx], sizeof(httpc_response_buf) - write_idx -1);if (r > 0) {write_idx += r;}} while(r > 0 && write_idx < (sizeof(httpc_response_buf) - 1));printf("... done reading from socket. Last read return=%d write_idx=%u errno=%d.\n", r, write_idx, errno);/* 打印服务器返回的数据 */for	(int i = 0; i < write_idx; ++i) {putchar(httpc_response_buf[i]);}puts("");/* 解析天气预报数据 */ret = cJSON_DailyWeatherParse(httpc_response_buf, &weather_data);if (ret == 0) {/* 格式化打印天气预报信息 */DisplayWeather(&weather_data);}close(s);
}

由于服务器返回的天气预报数据为json字符串, 我们编写函数cJSON_DailyWeatherParse解析天气预报json数据并保存到结构体变量weather_data中，cJSON_DailyWeatherParse函数和DisplayWeather函数的定义如下:

static int cJSON_DailyWeatherParse(char *JSON, Weather_T *result)
{cJSON *json,*arrayItem,*object,*subobject,*item,*sub_child_object,*child_Item;json = cJSON_Parse(JSON); //解析JSON数据包if(json == NULL)		  //检测JSON数据包是否存在语法上的错误，返回NULL表示数据包无效{printf("Error before: [%s]\n",cJSON_GetErrorPtr()); //打印数据包语法错误的位置return 1;}else{if ((arrayItem = cJSON_GetObjectItem(json,"results")) != NULL) //匹配字符串"results",获取数组内容{// int size = cJSON_GetArraySize(arrayItem);     //获取数组中对象个数
#if DEBUGprintf("Get Array Size: size=%d\n",size);
#endifif((object = cJSON_GetArrayItem(arrayItem,0)) != NULL)//获取父对象内容{/* 匹配子对象1------结构体location */if((subobject = cJSON_GetObjectItem(object,"location")) != NULL){if((item = cJSON_GetObjectItem(subobject,"name")) != NULL) //匹配子对象1成员"name"{memcpy(result->name, item->valuestring,strlen(item->valuestring)); 		// 保存数据供外部调用}}/* 匹配子对象2------数组daily */if((subobject = cJSON_GetObjectItem(object,"daily")) != NULL){int sub_array_size = cJSON_GetArraySize(subobject);
#if DEBUGprintf("Get Sub Array Size: sub_array_size=%d\n",sub_array_size);
#endiffor(int i = 0; i < sub_array_size; i++){if((sub_child_object = cJSON_GetArrayItem(subobject,i))!=NULL){// 匹配日期if((child_Item = cJSON_GetObjectItem(sub_child_object,"date")) != NULL){memcpy(result->date[i], child_Item->valuestring,strlen(child_Item->valuestring)); 		// 保存数据}// 匹配白天天气现象文字if((child_Item = cJSON_GetObjectItem(sub_child_object,"text_day")) != NULL){memcpy(result->text_day[i], child_Item->valuestring,strlen(child_Item->valuestring)); 	// 保存数据}// 匹配白天天气现象代码if((child_Item = cJSON_GetObjectItem(sub_child_object,"code_day")) != NULL){memcpy(result->code_day[i], child_Item->valuestring,strlen(child_Item->valuestring)); 	// 保存数据}// 匹配夜间天气现象代码if((child_Item = cJSON_GetObjectItem(sub_child_object,"code_night")) != NULL){memcpy(result->code_night[i], child_Item->valuestring,strlen(child_Item->valuestring)); // 保存数据}// 匹配最高温度if((child_Item = cJSON_GetObjectItem(sub_child_object,"high")) != NULL){memcpy(result->high[i], child_Item->valuestring,strlen(child_Item->valuestring)); 		//保存数据}// 匹配最低温度if((child_Item = cJSON_GetObjectItem(sub_child_object,"low")) != NULL){memcpy(result->low[i], child_Item->valuestring,strlen(child_Item->valuestring)); 		// 保存数据}// 匹配风向if((child_Item = cJSON_GetObjectItem(sub_child_object,"wind_direction")) != NULL){memcpy(result->wind_direction[i],child_Item->valuestring,strlen(child_Item->valuestring)); //保存数据}// 匹配风速，单位km/h（当unit=c时）if((child_Item = cJSON_GetObjectItem(sub_child_object,"wind_speed")) != NULL){memcpy(result->wind_speed[i], child_Item->valuestring,strlen(child_Item->valuestring)); // 保存数据}// 匹配风力等级if((child_Item = cJSON_GetObjectItem(sub_child_object,"wind_scale")) != NULL){memcpy(result->wind_scale[i], child_Item->valuestring,strlen(child_Item->valuestring)); // 保存数据}}}}/* 匹配子对象3------最后一次更新的时间 */if((subobject = cJSON_GetObjectItem(object,"last_update")) != NULL){//printf("%s:%s\n",subobject->string,subobject->valuestring);}}}}cJSON_Delete(json); //释放cJSON_Parse()分配出来的内存空间return 0;
}/*******************************************************************************************************
** 函数: DisplayWeather，显示天气数据
**------------------------------------------------------------------------------------------------------
** 参数: weather_data：天气数据
** 返回: void
********************************************************************************************************/
static void DisplayWeather(Weather_T *weather_data)
{printf("===========%s近三天的天气情况如下===========\n",weather_data->name);printf("【%s】\n",weather_data->date[0]);printf("天气：%s\n",weather_data->text_day[0]);printf("最高温：%s℃\n",weather_data->high[0]);printf("最低温：%s℃\n",weather_data->low[0]);printf("风向：%s\n",weather_data->wind_direction[0]);printf("风速：%skm/h\n",weather_data->wind_speed[0]);printf("风力等级：%s\n",weather_data->wind_scale[0]);printf("\n");printf("【%s】\n",weather_data->date[1]);printf("天气：%s\n",weather_data->text_day[1]);printf("最高温：%s℃\n",weather_data->high[1]);printf("最低温：%s℃\n",weather_data->low[1]);printf("风向：%s\n",weather_data->wind_direction[1]);printf("风速：%skm/h\n",weather_data->wind_speed[1]);printf("风力等级：%s\n",weather_data->wind_scale[1]);printf("\n");printf("【%s】\n",weather_data->date[2]);printf("天气：%s\n",weather_data->text_day[2]);printf("最高温：%s℃\n",weather_data->high[2]);printf("最低温：%s℃\n",weather_data->low[2]);printf("风向：%s\n",weather_data->wind_direction[2]);printf("风速：%skm/h\n",weather_data->wind_speed[2]);printf("风力等级：%s\n",weather_data->wind_scale[2]);
}

7. 编译工程
   bear make build -j 8
8. 烧录镜像到xr806
   首先使用USB线将开发板连上电脑，可能需要重新安装CP2102驱动，下载地址为CP2102驱动，在Windows中打开powershell,输入如下命令:

PS C:\Users\30751\Desktop> usbipd wsl list
BUSID  VID:PID    DEVICE                                                        STATE
2-1    10c4:ea60  Silicon Labs CP210x USB to UART Bridge (COM3)                 Not attached
2-3    248a:8367  USB 输入设备                                                  Not attached
2-6    0c45:6a1b  Integrated Webcam                                             Not attached
2-10   8087:0026  英特尔(R) 无线 Bluetooth(R)                                   Not attached

我们可以看到开发板连接的USB端口的的BUSID为2-1，接着使用如下命令将该USB串口共享给WSL:

PS C:\Users\30751\Desktop> usbipd wsl attach --busid 2-1
usbipd: info: Using default WSL distribution 'Ubuntu-20.04'; specify the '--distribution' option to select a different one.

接下来我们在Ubuntu终端中进入工程源码目录下的tools目录下，开启固件烧录USB串口的读写权限:
sudo chmod 666 /dev/ttyUSB0
使用如下命令烧录镜像到xr806
./phoenixMC
烧录成功信息如下:

我们再次在Windows中打开powershell,输入如下命令将开发板连接到windows:
usbipd wsl detach --busid 2-1
我们在windows中打开终端软件Tera Term，连上开发板串口,复位开发板将会看到如下信息:

use default flash chip mJedec 0x0
[FD I]: mode: 0x10, freq: 96000000Hz, drv: 0
[FD I]: jedec: 0x0, suspend_support: 1
mode select:ewlan information ===================================================
firmware:version : R0-XR_C07.08.52.67_ULP_R_02.132 Jan 10 2023 19:14:11-Y02.132buffer  : 8
driver:version : XR_V02.06.10
mac address:in use        : 8c:6d:08:3d:14:01in use        : 8c:6d:08:3d:14:02
====================================================================wlan mode:aplatform information ===============================================
XR806 SDK v1.2.2  Oct 21 2023 23:46:57 62800400heap space [0x217098, 0x24bc00), size 215912cpu  clock 160000000 Hz
HF   clock  40000000 Hzsdk option:XIP           : enableINT LF OSC    : enableINT LDO       : selectINT LDO / EXT PWR: enableSIP flash     : enablemac address:efuse         : 80:74:84:05:b9:cain use        : 8c:6d:08:3d:14:01
====================================================================[net INF] no need to switch wlan mode 0
[net INF] msg <wlan scan success>
en1: Trying to associate with 8c:ab:8e:fd:c3:58 (SSID='302' freq=2412 MHz)
en1: Associated with 8c:ab:8e:fd:c3:58
en1: WPA: Key negotiation completed with 8c:ab:8e:fd:c3:58 [PTK=CCMP GTK=TKIP]
en1: CTRL-EVENT-CONNECTED - Connection to 8c:ab:8e:fd:c3:58 completed [id=0 id_str=]
[net INF] msg <wlan connected>
[net INF] netif is link up
[net INF] start DHCP...
WAR drop=1135, fctl=0x00d0.
[net INF] netif (IPv4) is up
[net INF] address: 192.168.2.107
[net INF] gateway: 192.168.2.1
[net INF] netmask: 255.255.255.0
[net INF] msg <network up>
local ip: 192.168.2.107
gw: 192.168.2.1
netmask: 255.255.255.0
DNS lookup succeeded. IP=116.62.81.138
... allocated socket
... connected
... socket send success
... done reading from socket. Last read return=0 write_idx=995 errno=107.
{"results":[{"location":{"id":"WX4FBXXFKE4F","name":"北京","country":"CN","path":"北京,北京,中国","timezone":"Asia/Shanghai","timezone_offset":"+08:00"},"daily":[{"date":"2023-10-22","text_day":"晴","code_day":"0","text_night":"晴","code_night":"1","high":"21","low":"6","rainfall":"0.00","precip":"0.00","wind_direction":"无持续风向","wind_direction_degree":"","wind_speed":"8.4","wind_scale":"2","humidity":"61"},{"date":"2023-10-23","text_day":"晴","code_day":"0","text_night":"晴","code_night":"1","high":"21","low":"7","rainfall":"0.00","precip":"0.00","wind_direction":"无持续风向","wind_direction_degree":"","wind_speed":"3.0","wind_scale":"1","humidity":"75"},{"date":"2023-10-24","text_day":"晴","code_day":"0","text_night":"晴","code_night":"1","high":"23","low":"9","rainfall":"0.00","precip":"0.00","wind_direction":"无持续风向","wind_direction_degree":"","wind_speed":"3.0","wind_scale":"1","humidity":"75"}],"last_update":"2023-10-20T08:00:00+08:00"}]}
===========北京近三天的天气情况如下===========
【2023-10-22】
天气：晴
最高温：21℃
最低温：6℃
风向：无持续风向
风速：8.4km/h
风力等级：2【2023-10-23】
天气：晴
最高温：21℃
最低温：7℃
风向：无持续风向
风速：3.0km/h
风力等级：1【2023-10-24】
天气：晴
最高温：23℃
最低温：9℃
风向：无持续风向
风速：3.0km/h
风力等级：1

可以看到我们已经成功获取了北京的未来三天的天气情况.

4. 总结

通过本次开发板评测，掌握了XR806的WiFi相关API的使用，系统事件监听API的使用掌，握了sokect网络编程相关知识，掌握了cJSON的使用. XR806是一款性价比很高的WiFi/BLE MCU，官方提供的SDK完善，文档丰富，是物联网相关的项目的理想选择.

附件:工程源码仓库