OpenHarmony轻量系统开发【9】WiFi之STA模式连接热点-编程知识

9.1AT指令操作WiFi

我们可以使用AT指令进行Hi3861 WiFi操作，连接热点、ping服务器等。

但是很多时候，我们需要实现开机后自动连接到某个热点，光靠AT指令不行。
Hi3861 为我们提供了WiFi操作的相关API，方便我们编写代码，实现热点连接。

9.2 代码实现

先直接上代码和操作演示。
跟我们最早的hello world代码一样，在app下新增业务demo_wifi_sta，其中demo_wifi_sta.c为业务代码，BUILD.gn为编译脚本，具体规划目录结构如下：

其中BUILD.gn文件内容如下：

static_library("demo_wifi_sta") {sources = ["demo_wifi_sta.c"]include_dirs = ["//utils/native/lite/include","//kernel/liteos_m/components/cmsis/2.0","//base/iot_hardware/peripheral/interfaces/kits","//device/soc/hisilicon/hi3861v100/hi3861_adapter/hals/communication/wifi_lite/wifiservice","//device/soc/hisilicon/hi3861v100/hi3861_adapter/kal","//device/soc/hisilicon/hi3861v100/sdk_liteos/third_party/lwip_sack/include",]
}

hi_wifi_start_sta函数：设置WiFi参数、扫描热点

int hi_wifi_start_sta(void)
{int ret;char ifname[WIFI_IFNAME_MAX_SIZE + 1] = {0};int len = sizeof(ifname);const unsigned char wifi_vap_res_num = APP_INIT_VAP_NUM;const unsigned char wifi_user_res_num = APP_INIT_USR_NUM;unsigned int  num = WIFI_SCAN_AP_LIMIT;//这里不需要重复进行WiFi init，因为系统启动后就自己会做WiFi init
#if 0printf("_______>>>>>>>>>> %s %d \r\n", __FILE__, __LINE__);ret = hi_wifi_init(wifi_vap_res_num, wifi_user_res_num);if (ret != HISI_OK) {return -1;}
#endifret = hi_wifi_sta_start(ifname, &len);if (ret != HISI_OK) {return -1;}/* register call back function to receive wifi event, etc scan results event,* connected event, disconnected event.*/ret = hi_wifi_register_event_callback(wifi_wpa_event_cb);if (ret != HISI_OK) {printf("register wifi event callback failed\n");}/* acquire netif for IP operation */g_lwip_netif = netifapi_netif_find(ifname);if (g_lwip_netif == NULL) {printf("%s: get netif failed\n", __FUNCTION__);return -1;}/* 开始扫描附件的WiFi热点 */ret = hi_wifi_sta_scan();if (ret != HISI_OK) {return -1;}sleep(5);   /* sleep 5s, waiting for scan result. */hi_wifi_ap_info *pst_results = malloc(sizeof(hi_wifi_ap_info) * WIFI_SCAN_AP_LIMIT);if (pst_results == NULL) {return -1;}//把扫描到的热点结果存储起来ret = hi_wifi_sta_scan_results(pst_results, &num);if (ret != HISI_OK) {free(pst_results);return -1;}//打印扫描到的所有热点for (unsigned int loop = 0; (loop < num) && (loop < WIFI_SCAN_AP_LIMIT); loop++) {printf("SSID: %s\n", pst_results[loop].ssid);}free(pst_results);/* 开始接入热点 */ret = hi_wifi_start_connect();if (ret != 0) {return -1;}return 0;
}

连接热点：

int hi_wifi_start_connect(void)
{int ret;errno_t rc;hi_wifi_assoc_request assoc_req = {0};/* copy SSID to assoc_req */rc = memcpy_s(assoc_req.ssid, HI_WIFI_MAX_SSID_LEN + 1, "RedmiK40", 8); /* 9:ssid length */if (rc != EOK) {return -1;}//热点加密方式assoc_req.auth = HI_WIFI_SECURITY_WPA2PSK;/* 热点密码 */memcpy(assoc_req.key, "07686582488", 11);ret = hi_wifi_sta_connect(&assoc_req);if (ret != HISI_OK) {return -1;}return 0;
}

热点连接结果回调函数

void wifi_wpa_event_cb(const hi_wifi_event *hisi_event)
{if (hisi_event == NULL)return;switch (hisi_event->event) {case HI_WIFI_EVT_SCAN_DONE:printf("WiFi: Scan results available\n");break;case HI_WIFI_EVT_CONNECTED:printf("WiFi: Connected\n");netifapi_dhcp_start(g_lwip_netif);break;case HI_WIFI_EVT_DISCONNECTED:printf("WiFi: Disconnected\n");netifapi_dhcp_stop(g_lwip_netif);hi_sta_reset_addr(g_lwip_netif);break;case HI_WIFI_EVT_WPS_TIMEOUT:printf("WiFi: wps is timeout\n");break;default:break;}
}

hi_sta_reset_addr：重新复位sta的地址、网关等参数。

/* clear netif's ip, gateway and netmask */
void hi_sta_reset_addr(struct netif *pst_lwip_netif)
{ip4_addr_t st_gw;ip4_addr_t st_ipaddr;ip4_addr_t st_netmask;if (pst_lwip_netif == NULL) {printf("hisi_reset_addr::Null param of netdev\r\n");return;}IP4_ADDR(&st_gw, 0, 0, 0, 0);IP4_ADDR(&st_ipaddr, 0, 0, 0, 0);IP4_ADDR(&st_netmask, 0, 0, 0, 0);netifapi_netif_set_addr(pst_lwip_netif, &st_ipaddr, &st_netmask, &st_gw);
}

9.3 WiFi相关API

Hi3861 提供了非常多的wifi相关API，主要文件是 hi_wifi_api.h
我们这里只列举最重要的几个API

（1）开启STA

int hi_wifi_sta_start(char *ifname, int *len);

（2）停止STA

int hi_wifi_sta_stop(void);

（3）扫描附件的热点

int hi_wifi_sta_scan(void);

（4）连接热点

int hi_wifi_sta_connect(hi_wifi_assoc_request *req);

其中hi_wifi_assoc_request *req 结构的定义如下：

typedef struct {char ssid[HI_WIFI_MAX_SSID_LEN + 1];    /**< SSID. CNcomment: SSID 只支持ASCII字符.CNend */hi_wifi_auth_mode auth;                 /**< Authentication mode. CNcomment: 认证类型.CNend */char key[HI_WIFI_MAX_KEY_LEN + 1];      /**< Secret key. CNcomment: 秘钥.CNend */unsigned char bssid[HI_WIFI_MAC_LEN];   /**< BSSID. CNcomment: BSSID.CNend */hi_wifi_pairwise pairwise;              /**< Encryption type. CNcomment: 加密方式,不需指定时置0.CNend */
} hi_wifi_assoc_request;

这里需要注意的是，通常加密方式是：HI_WIFI_SECURITY_WPA2PSK

例如我家的热点的连接方式的代码实现如下：

int hi_wifi_start_connect(void)
{int ret;errno_t rc;hi_wifi_assoc_request assoc_req = {0};/* copy SSID to assoc_req */rc = memcpy_s(assoc_req.ssid, HI_WIFI_MAX_SSID_LEN + 1, "RedmiK40", 8); /* 9:ssid length */if (rc != EOK) {return -1;}//热点加密方式assoc_req.auth = HI_WIFI_SECURITY_WPA2PSK;/* 热点密码 */memcpy(assoc_req.key, "07686582488", 11);ret = hi_wifi_sta_connect(&assoc_req);if (ret != HISI_OK) {return -1;}return 0;
}

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