zh_espnow/README.md

# ESP32 ESP-IDF component for ESP-NOW interface

## Tested on

ESP32 ESP-IDF v5.4

## Features

1. The maximum size of transmitted data is up to 1490 bytes.
2. Support of any data types.
3. All nodes are not visible to the network scanner.
4. Not required a pre-pairings for data transfer.
5. Broadcast or unicast data transmissions.
6. Possibility uses WiFi AP or STA modes at the same time with ESP-NOW.

## Attention

1. For correct operation in ESP-NOW + STA mode, your WiFi router must be set to the same channel as ESP-NOW.
2. All devices on the network must have the same WiFi channel.

## Using

In an existing project, run the following command to install the component:

```text
cd ../your_project/components
git clone https://github.com/aZholtikov/zh_espnow.git
```

In the application, add the component:

```c
#include "zh_espnow.h"
```

## Example

Sending and receiving messages:

```c
#include "nvs_flash.h"
#include "esp_netif.h"
#include "zh_espnow.h"
#ifdef CONFIG_IDF_TARGET_ESP8266
#include "esp_system.h"
#else
#include "esp_random.h"
#endif

#define MAC2STR(a) (a)[0], (a)[1], (a)[2], (a)[3], (a)[4], (a)[5]

void zh_espnow_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data);

uint8_t target[6] = {0x34, 0x94, 0x54, 0x24, 0xA3, 0x41};

typedef struct
{
    char char_value[30];
    int int_value;
    float float_value;
    bool bool_value;
} example_message_t;

void app_main(void)
{
    esp_log_level_set("zh_espnow", ESP_LOG_NONE);
    nvs_flash_init();
    esp_netif_init();
    esp_event_loop_create_default();
    wifi_init_config_t wifi_init_config = WIFI_INIT_CONFIG_DEFAULT();
    esp_wifi_init(&wifi_init_config);
    esp_wifi_set_mode(WIFI_MODE_STA);
    esp_wifi_start();
    zh_espnow_init_config_t espnow_init_config = ZH_ESPNOW_INIT_CONFIG_DEFAULT();
    zh_espnow_init(&espnow_init_config);
#ifdef CONFIG_IDF_TARGET_ESP8266
    esp_event_handler_register(ZH_ESPNOW, ESP_EVENT_ANY_ID, &zh_espnow_event_handler, NULL);
#else
    esp_event_handler_instance_register(ZH_ESPNOW, ESP_EVENT_ANY_ID, &zh_espnow_event_handler, NULL, NULL);
#endif
    example_message_t send_message = {0};
    strcpy(send_message.char_value, "THIS IS A CHAR");
    send_message.float_value = 1.234;
    send_message.bool_value = false;
    for (;;)
    {
        send_message.int_value = esp_random();
        zh_espnow_send(NULL, (uint8_t *)&send_message, sizeof(send_message));
        vTaskDelay(5000 / portTICK_PERIOD_MS);
        zh_espnow_send(target, (uint8_t *)&send_message, sizeof(send_message));
        vTaskDelay(5000 / portTICK_PERIOD_MS);
    }
}

void zh_espnow_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data)
{
    switch (event_id)
    {
    case ZH_ESPNOW_ON_RECV_EVENT:;
        zh_espnow_event_on_recv_t *recv_data = event_data;
        printf("Message from MAC %02X:%02X:%02X:%02X:%02X:%02X is received. Data lenght %d bytes.\n", MAC2STR(recv_data->mac_addr), recv_data->data_len);
        example_message_t *recv_message = (example_message_t *)recv_data->data;
        printf("Char %s\n", recv_message->char_value);
        printf("Int %d\n", recv_message->int_value);
        printf("Float %f\n", recv_message->float_value);
        printf("Bool %d\n", recv_message->bool_value);
        heap_caps_free(recv_data->data); // Do not delete to avoid memory leaks!
        break;
    case ZH_ESPNOW_ON_SEND_EVENT:;
        zh_espnow_event_on_send_t *send_data = event_data;
        if (send_data->status == ZH_ESPNOW_SEND_SUCCESS)
        {
            printf("Message to MAC %02X:%02X:%02X:%02X:%02X:%02X sent success.\n", MAC2STR(send_data->mac_addr));
        }
        else
        {
            printf("Message to MAC %02X:%02X:%02X:%02X:%02X:%02X sent fail.\n", MAC2STR(send_data->mac_addr));
        }
    default:
        break;
    }
}
```

Any [feedback](mailto:github@azholtikov.ru) will be gladly accepted.