ESP-Nodes/ESP32-IDF_ESPNOW-Transmitter/main/transmitter.c

#include <stdlib.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "esp_adc/adc_oneshot.h"
#include "nvs_flash.h"
#include "esp_event.h"
#include "esp_netif.h"
#include "esp_wifi.h"
#include "esp_log.h"
#include "esp_err.h"
#include "esp_mac.h"
#include "esp_now.h"

#include "sensors_data.h"
#include "system_health.h"
#include "config.h"

esp_now_peer_info_t devices;
static sensors_data_t buffer;
static float temperature_value = 0.0;
static int espnow_channel = 1;

// Function to delete peer (i.e. when communication error occurs)
static void deletePeer (void) 
{
    uint8_t delStatus = esp_now_del_peer(receiver_mac);
    if (delStatus != 0) {
        ESP_LOGE(TAG, "Could not delete peer");
    }
}

static void sendData (void)
{
    buffer.crc = 0;
    buffer.sensor1 = 0;
    buffer.sensor2 = 0;
    buffer.sensor3 = false;
    buffer.sensor4 = 0.0;
    buffer.motor1_rpm_pwm = 0;
    buffer.motor2_rpm_pwm = 0;
    buffer.motor3_rpm_pwm = 0;
    buffer.motor4_rpm_pwm = 0;

    get_chip_temperature(&temperature_value);
    buffer.sensor4 = temperature_value;

    // Call ESP-NOW function to send data (MAC address of receiver, pointer to the memory holding data & data length)
    uint8_t result = esp_now_send((uint8_t*)receiver_mac, (uint8_t *)&buffer, sizeof(buffer));
    
    // If status is NOT OK, display error message and error code (in hexadecimal).
    if (result != 0) {
        ESP_LOGE(TAG, "Error sending data! Error code: 0x%04X", result);
        ESP_LOGE(TAG, "esp_now_send() failed: %s", esp_err_to_name(result));
        ESP_LOGE(TAG, "==========================");
        ESP_LOGE(TAG, "Ensure that received MAC is: %02X:%02X:%02X:%02X:%02X:%02X",
                 receiver_mac[0], receiver_mac[1], receiver_mac[2],
                 receiver_mac[3], receiver_mac[4], receiver_mac[5]);
    }
}

// Callback function to handle the status of data transmission
// This function is called when the data is sent or if there is an error.
static void statusDataSend(const uint8_t *mac_addr, esp_now_send_status_t status)
{
    if (status == ESP_NOW_SEND_SUCCESS) {
        ESP_LOGI(TAG, "Data sent successfully to: %02X:%02X:%02X:%02X:%02X:%02X",
                 mac_addr[0], mac_addr[1], mac_addr[2],
                 mac_addr[3], mac_addr[4], mac_addr[5]);
    } else if (status != ESP_NOW_SEND_SUCCESS) {// == ESP_NOW_SEND_FAIL) {
        ESP_LOGE(TAG, "Error sending data to: %02X:%02X:%02X:%02X:%02X:%02X",
                 mac_addr[0], mac_addr[1], mac_addr[2],
                 mac_addr[3], mac_addr[4], mac_addr[5]);
        ESP_LOGE(TAG, "Error sending data. Error code: 0x%04X", status);
        ESP_LOGE(TAG, "esp_now_send() failed: %s", esp_err_to_name(status));
        ESP_LOGE(TAG, "Ensure that receiver is powered-on and MAC is correct.");       

        esp_now_del_peer(receiver_mac);
        esp_now_deinit();
        esp_wifi_set_channel(espnow_channel, WIFI_SECOND_CHAN_NONE);
        esp_now_init();
        memcpy(devices.peer_addr, receiver_mac, 6);
        devices.channel = espnow_channel;
        devices.encrypt = false;
        esp_now_add_peer(&devices);
        esp_now_register_send_cb(statusDataSend);
        if (espnow_channel < 11) {
            espnow_channel++;
        }
    }
}

/* WiFi should start before using ESPNOW */
void wifi_init()
{
    /*
    * STAND-ALONE
    */
    ESP_ERROR_CHECK(esp_netif_init());
    ESP_ERROR_CHECK(esp_event_loop_create_default());
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
    ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) );
    ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA));//ESPNOW_WIFI_MODE));
    ESP_ERROR_CHECK( esp_wifi_start());
    //ESP_ERROR_CHECK( esp_wifi_set_channel(CONFIG_ESPNOW_CHANNEL, WIFI_SECOND_CHAN_NONE));
    ESP_ERROR_CHECK( esp_wifi_set_channel(espnow_channel, WIFI_SECOND_CHAN_NONE)); // 2
    #if CONFIG_ESPNOW_ENABLE_LONG_RANGE
    ESP_ERROR_CHECK( esp_wifi_set_protocol(ESPNOW_WIFI_IF, WIFI_PROTOCOL_11B|WIFI_PROTOCOL_11G|WIFI_PROTOCOL_11N|WIFI_PROTOCOL_LR) );
    #endif  
    /*
    * WI-FI
    */
    /*
    ESP_ERROR_CHECK(esp_netif_init());
    ESP_ERROR_CHECK(esp_event_loop_create_default());
    esp_netif_create_default_wifi_sta();
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
    ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) );
    ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA));//ESPNOW_WIFI_MODE));
    wifi_config_t wifi_config = {
        .sta = {
            .ssid = "IoT_bots2",
            .password = "208208208",
        },
    };
    ESP_ERROR_CHECK (esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
    //ESP_ERROR_CHECK( esp_wifi_set_channel(CONFIG_ESPNOW_CHANNEL, WIFI_SECOND_CHAN_NONE));
    ESP_ERROR_CHECK( esp_wifi_start());
    //ESP_ERROR_CHECK( esp_wifi_set_channel(CONFIG_ESPNOW_CHANNEL, WIFI_SECOND_CHAN_NONE));
    ESP_ERROR_CHECK( esp_wifi_connect() );
    */
}

// Task to periodically send ESPNOW remote control data
static void rc_send_data_task()
{
    while (true) {
        if (esp_now_is_peer_exist((uint8_t*)receiver_mac)) {
            sendData();
        }
        vTaskDelay (250 / portTICK_PERIOD_MS);
    }
}

void transmission_init()
{
    esp_err_t espnow_ret = esp_now_init();
    if (espnow_ret != ESP_OK) {
        ESP_LOGE(TAG, "esp_now_init() failed: %s", esp_err_to_name(espnow_ret));
        return;
    }
    ESP_LOGI(TAG, "ESPNOW initialized successfully");
    esp_now_register_send_cb(statusDataSend);

    // Specify ESP-NOW receiver device configuration values
    memcpy(devices.peer_addr, receiver_mac, 6);
    devices.channel = espnow_channel;
    devices.encrypt = false;
    esp_now_add_peer(&devices);

    // Defince a task for periodically sending ESPNOW remote control data
    xTaskCreate(rc_send_data_task, "RC", 8096, NULL, 4, NULL);
}