1、什么是espnow

短數據傳輸、無連接的快速通訊技術

2、應用范圍智能照明控制

（一）、 ESPNOW例程。

下面的例程展示了怎樣使用ESPNOW

步驟：

1、初始化wifi

A、TCP/ip適配器初始化

a、注冊事件處理函數初始化。

b、設置配置信息

c、選擇存儲類型

d、選擇wifi模式AP

e、啟動wifi

f、啟動wifi后設置通道，假如兩個設備在同一個通道上就不需要設置

2、初始化espnow

a、創建個隊列

b、注冊發送數據回調函數

c、注冊接受數據回調函數

d、設置主秘鑰

e、添加廣播點信息來點列表

f、初始化發送參數

g、創建espnow任務

*/

#include <stdlib.h>

#include <time.h>

#include <string.h>

#include <assert.h>

#include "freertos/FreeRTOS.h"

#include "freertos/semphr.h"

#include "freertos/timers.h"

#include "nvs_flash.h"

#include "esp_event_loop.h"

#include "tcpip_adapter.h"

#include "esp_wifi.h"

#include "esp_log.h"

#include "esp_system.h"

#include "esp_now.h"

#include "rom/ets_sys.h"

#include "rom/crc.h"

#include "espnow_example.h"

static const char *TAG = "espnow_example";

static xQueueHandle example_espnow_queue;

static uint8_t example_broadcast_mac[ESP_NOW_ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };

static uint16_t s_example_espnow_seq[EXAMPLE_ESPNOW_DATA_MAX] = { 0, 0 };

static void example_espnow_deinit(example_espnow_send_param_t *send_param);

1、事件處理函數

static esp_err_t example_event_handler(void *ctx, system_event_t *event)

{

??switch(event->event_id) {

??case SYSTEM_EVENT_STA_START: ? ? ? ? ? ? ? ? ? ?wifi啟動完成

????ESP_LOGI(TAG, "WiFi started");

????break;

??default:

????break;

??}

??return ESP_OK;

}

2、wifi初始化

static void example_wifi_init(void)

{

??tcpip_adapter_init(); TCP/ip適配器初始化

??ESP_ERROR_CHECK( esp_event_loop_init(example_event_handler, NULL) ); 注冊事件處理函數初始化。

??wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT(); 獲取wifi配置信息

??ESP_ERROR_CHECK( esp_wifi_init(&cfg) ); 設置配置信息

??ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) ); 選擇存儲類型

??ESP_ERROR_CHECK( esp_wifi_set_mode(ESPNOW_WIFI_MODE) ); 選擇wifi模式AP

??ESP_ERROR_CHECK( esp_wifi_start()); 啟動wifi

??ESP_ERROR_CHECK( esp_wifi_set_channel(CONFIG_ESPNOW_CHANNEL, 0) ); 啟動wifi后設置通道，假如兩個設備在同一個通道上就不需要設置

}

1、發送數據回調函數

static void example_espnow_send_cb(const uint8_t *mac_addr, esp_now_send_status_t status)

{

??example_espnow_event_t evt;

??example_espnow_event_send_cb_t *send_cb = &evt.info.send_cb;

??if (mac_addr == NULL) {

????ESP_LOGE(TAG, "Send cb arg error");

????return;

??}

設置發送事件，并添加到隊列中去

??evt.id = EXAMPLE_ESPNOW_SEND_CB;

??memcpy(send_cb->mac_addr, mac_addr, ESP_NOW_ETH_ALEN);

??send_cb->status = status;

??if (xQueueSend(example_espnow_queue, &evt, portMAX_DELAY) != pdTRUE) {

????ESP_LOGW(TAG, "Send send queue fail");

??}

}

2、接受回調函數

static void example_espnow_recv_cb(const uint8_t *mac_addr, const uint8_t *data, int len)

{

??example_espnow_event_t evt;

??example_espnow_event_recv_cb_t *recv_cb = &evt.info.recv_cb;

??if (mac_addr == NULL || data == NULL || len <= 0) {

????ESP_LOGE(TAG, "Receive cb arg error");

????return;

??}

設置接受事件，并添加到隊列中

??evt.id = EXAMPLE_ESPNOW_RECV_CB;

??memcpy(recv_cb->mac_addr, mac_addr, ESP_NOW_ETH_ALEN);

??recv_cb->data = malloc(len);

??if (recv_cb->data == NULL) {

????ESP_LOGE(TAG, "Malloc receive data fail");

????return;

??}

??memcpy(recv_cb->data, data, len);

??recv_cb->data_len = len;

??if (xQueueSend(example_espnow_queue, &evt, portMAX_DELAY) != pdTRUE) {

????ESP_LOGW(TAG, "Send receive queue fail");

????free(recv_cb->data);

??}

}

3、解析接收到的 ESPNOW數據（驗證crc校驗）

int example_espnow_data_parse(uint8_t *data, uint16_t data_len, uint8_t *state, uint16_t *seq, int *magic)

{

??example_espnow_data_t *buf = (example_espnow_data_t *)data;

??uint16_t crc, crc_cal = 0;

??if (data_len < sizeof(example_espnow_data_t)) {

????ESP_LOGE(TAG, "Receive ESPNOW data too short, len:%d", data_len);

????return -1;

??}

??*state = buf->state;

??*seq = buf->seq_num;

??*magic = buf->magic;

??crc = buf->crc;

??buf->crc = 0;

??crc_cal = crc16_le(UINT16_MAX, (uint8_t const *)buf, data_len);

??if (crc_cal == crc) {

????return buf->type;

??}

??return -1;

}

4、準備 ESPNOW 發送的數據

void example_espnow_data_prepare(example_espnow_send_param_t *send_param)

{

??example_espnow_data_t *buf = (example_espnow_data_t *)send_param->buffer;

??int i = 0;

??assert(send_param->len >= sizeof(example_espnow_data_t));

??buf->type = IS_BROADCAST_ADDR(send_param->dest_mac) ? EXAMPLE_ESPNOW_DATA_BROADCAST : EXAMPLE_ESPNOW_DATA_UNICAST;

??buf->state = send_param->state;

??buf->seq_num = s_example_espnow_seq[buf->type]++;

??buf->crc = 0;

??buf->magic = send_param->magic;

??for (i = 0; i < send_param->len - sizeof(example_espnow_data_t); i++) {

????buf->payload[i] = (uint8_t)esp_random();

??}

??buf->crc = crc16_le(UINT16_MAX, (uint8_t const *)buf, send_param->len);

}

1、espnow任務處理函數

static void example_espnow_task(void *pvParameter)

{

??example_espnow_event_t evt;

??uint8_t recv_state = 0;

??uint16_t recv_seq = 0;

??int recv_magic = 0;

??bool is_broadcast = false;

??int ret;

??vTaskDelay(5000 / portTICK_RATE_MS);

??ESP_LOGI(TAG, "Start sending broadcast data");

??/* Start sending broadcast ESPNOW data. */

??example_espnow_send_param_t *send_param = (example_espnow_send_param_t *)pvParameter; 1、獲取發送參數

??if (esp_now_send(send_param->dest_mac, send_param->buffer, send_param->len) != ESP_OK) {

????ESP_LOGE(TAG, "Send error");

????example_espnow_deinit(send_param);

????vTaskDelete(NULL);

??} 3、開始發送數據

??while (xQueueReceive(example_espnow_queue, &evt, portMAX_DELAY) == pdTRUE) { ?4、判斷是否有事件產生

????switch (evt.id) {

??????case EXAMPLE_ESPNOW_SEND_CB: ? ? ? 5、發送事件處理函數

??????{

????????example_espnow_event_send_cb_t *send_cb = &evt.info.send_cb;

????????is_broadcast = IS_BROADCAST_ADDR(send_cb->mac_addr);

????????ESP_LOGD(TAG, "Send data to "MACSTR", status1: %d", MAC2STR(send_cb->mac_addr), send_cb->status);

????????if (is_broadcast && (send_param->broadcast == false)) {

??????????break;

????????}

????????if (!is_broadcast) {

??????????send_param->count--;

??????????if (send_param->count == 0) {

????????????ESP_LOGI(TAG, "Send done");

????????????example_espnow_deinit(send_param);

????????????vTaskDelete(NULL);

??????????}

????????}

????????/* Delay a while before sending the next data. */

????????if (send_param->delay > 0) {

??????????vTaskDelay(send_param->delay/portTICK_RATE_MS);

????????}

????????ESP_LOGI(TAG, "send data to "MACSTR"", MAC2STR(send_cb->mac_addr));

????????memcpy(send_param->dest_mac, send_cb->mac_addr, ESP_NOW_ETH_ALEN);

????????example_espnow_data_prepare(send_param);

????????/* Send the next data after the previous data is sent. */

????????if (esp_now_send(send_param->dest_mac, send_param->buffer, send_param->len) != ESP_OK) {

??????????ESP_LOGE(TAG, "Send error");

??????????example_espnow_deinit(send_param);

??????????vTaskDelete(NULL);

????????}

????????break;

??????}

??????case EXAMPLE_ESPNOW_RECV_CB: ? ?5、接受事件處理函數

??????{

????????example_espnow_event_recv_cb_t *recv_cb = &evt.info.recv_cb;

????????ret = example_espnow_data_parse(recv_cb->data, recv_cb->data_len, &recv_state, &recv_seq, &recv_magic);

????????free(recv_cb->data);

????????if (ret == EXAMPLE_ESPNOW_DATA_BROADCAST) {

??????????ESP_LOGI(TAG, "Receive %dth broadcast data from: "MACSTR", len: %d", recv_seq, MAC2STR(recv_cb->mac_addr), recv_cb->data_len);

??????????/* If MAC address does not exist in peer list, add it to peer list. */

??????????if (esp_now_is_peer_exist(recv_cb->mac_addr) == false) {

????????????esp_now_peer_info_t *peer = malloc(sizeof(esp_now_peer_info_t));

????????????if (peer == NULL) {

??????????????ESP_LOGE(TAG, "Malloc peer information fail");

??????????????example_espnow_deinit(send_param);

??????????????vTaskDelete(NULL);

????????????}

????????????memset(peer, 0, sizeof(esp_now_peer_info_t));

????????????peer->channel = CONFIG_ESPNOW_CHANNEL;

????????????peer->ifidx = ESPNOW_WIFI_IF;

????????????peer->encrypt = true;

????????????memcpy(peer->lmk, CONFIG_ESPNOW_LMK, ESP_NOW_KEY_LEN);

????????????memcpy(peer->peer_addr, recv_cb->mac_addr, ESP_NOW_ETH_ALEN);

????????????ESP_ERROR_CHECK( esp_now_add_peer(peer) );

????????????free(peer);

??????????}

??????????/* Indicates that the device has received broadcast ESPNOW data. */

??????????if (send_param->state == 0) {

????????????send_param->state = 1;

??????????}

??????????/* If receive broadcast ESPNOW data which indicates that the other device has received

???????????* broadcast ESPNOW data and the local magic number is bigger than that in the received

???????????* broadcast ESPNOW data, stop sending broadcast ESPNOW data and start sending unicast

???????????* ESPNOW data.

???????????*/

??????????if (recv_state == 1) {

????????????/* The device which has the bigger magic number sends ESPNOW data, the other one

?????????????* receives ESPNOW data.

?????????????*/

????????????if (send_param->unicast == false && send_param->magic >= recv_magic) {

?????????? ??ESP_LOGI(TAG, "Start sending unicast data");

?????????? ??ESP_LOGI(TAG, "send data to "MACSTR"", MAC2STR(recv_cb->mac_addr));

?????????? ??/* Start sending unicast ESPNOW data. */

??????????????memcpy(send_param->dest_mac, recv_cb->mac_addr, ESP_NOW_ETH_ALEN);

??????????????example_espnow_data_prepare(send_param);

??????????????if (esp_now_send(send_param->dest_mac, send_param->buffer, send_param->len) != ESP_OK) {

????????????????ESP_LOGE(TAG, "Send error");

????????????????example_espnow_deinit(send_param);

????????????????vTaskDelete(NULL);

??????????????}

??????????????else {

????????????????send_param->broadcast = false;

????????????????send_param->unicast = true;

??????????????}

????????????}

??????????}

????????}

????????else if (ret == EXAMPLE_ESPNOW_DATA_UNICAST) {

??????????ESP_LOGI(TAG, "Receive %dth unicast data from: "MACSTR", len: %d", recv_seq, MAC2STR(recv_cb->mac_addr), recv_cb->data_len);

??????????/* If receive unicast ESPNOW data, also stop sending broadcast ESPNOW data. */

??????????send_param->broadcast = false;

????????}

????????else {

??????????ESP_LOGI(TAG, "Receive error data from: "MACSTR"", MAC2STR(recv_cb->mac_addr));

????????}

????????break;

??????}

??????default:

????????ESP_LOGE(TAG, "Callback type error: %d", evt.id);

????????break;

????}

??}

}

static esp_err_t example_espnow_init(void)

{

??example_espnow_send_param_t *send_param;

??example_espnow_queue = xQueueCreate(ESPNOW_QUEUE_SIZE, sizeof(example_espnow_event_t)); 創建個隊列

??if (example_espnow_queue == NULL) {

????ESP_LOGE(TAG, "Create mutex fail");

????return ESP_FAIL;

??}

??/* Initialize ESPNOW and register sending and receiving callback function. */

??ESP_ERROR_CHECK( esp_now_init() ); 初始哈espnow

??ESP_ERROR_CHECK( esp_now_register_send_cb(example_espnow_send_cb) ); 注冊發送數據回調函數

??ESP_ERROR_CHECK( esp_now_register_recv_cb(example_espnow_recv_cb) );注冊接受數據回調函數

??

??ESP_ERROR_CHECK( esp_now_set_pmk((uint8_t *)CONFIG_ESPNOW_PMK) );設置主秘鑰

??/* Add broadcast peer information to peer list. */

??esp_now_peer_info_t *peer = malloc(sizeof(esp_now_peer_info_t));

??if (peer == NULL) {

????ESP_LOGE(TAG, "Malloc peer information fail");

????vSemaphoreDelete(example_espnow_queue);

????esp_now_deinit();

????return ESP_FAIL;

??}

??memset(peer, 0, sizeof(esp_now_peer_info_t));

??peer->channel = CONFIG_ESPNOW_CHANNEL;

??peer->ifidx = ESPNOW_WIFI_IF;

??peer->encrypt = false;

??memcpy(peer->peer_addr, example_broadcast_mac, ESP_NOW_ETH_ALEN);

??ESP_ERROR_CHECK( esp_now_add_peer(peer) ); 添加廣播點信息來點列表

??free(peer);

??/* Initialize sending parameters. */

??send_param = malloc(sizeof(example_espnow_send_param_t));

??memset(send_param, 0, sizeof(example_espnow_send_param_t));

??if (send_param == NULL) {

????ESP_LOGE(TAG, "Malloc send parameter fail");

????vSemaphoreDelete(example_espnow_queue);

????esp_now_deinit();

????return ESP_FAIL;

??}

??send_param->unicast = false;

??send_param->broadcast = true;

??send_param->state = 0;

??send_param->magic = esp_random();

??send_param->count = CONFIG_ESPNOW_SEND_COUNT;

??send_param->delay = CONFIG_ESPNOW_SEND_DELAY;

??send_param->len = CONFIG_ESPNOW_SEND_LEN;

??send_param->buffer = malloc(CONFIG_ESPNOW_SEND_LEN);

??if (send_param->buffer == NULL) {

????ESP_LOGE(TAG, "Malloc send buffer fail");

????free(send_param);

????vSemaphoreDelete(example_espnow_queue);

????esp_now_deinit();

????return ESP_FAIL;

??}

??memcpy(send_param->dest_mac, example_broadcast_mac, ESP_NOW_ETH_ALEN);

??example_espnow_data_prepare(send_param);初始化發送參數

??xTaskCreate(example_espnow_task, "example_espnow_task", 2048, send_param, 4, NULL);

創建espnow任務

??return ESP_OK;

}

5、釋放資源

static void example_espnow_deinit(example_espnow_send_param_t *send_param)

{

??free(send_param->buffer);

??free(send_param);

??vSemaphoreDelete(example_espnow_queue);

??esp_now_deinit();

}

void app_main()

{

??// 1、nvs初始化

??esp_err_t ret = nvs_flash_init();

??if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {

????ESP_ERROR_CHECK( nvs_flash_erase() );

????ret = nvs_flash_init();

??}

??ESP_ERROR_CHECK( ret );

// 2、wifi初始化

??example_wifi_init();

// 3 espnow初始化

??example_espnow_init();

}

總結

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