espnow 例程解析
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();
}
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