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ESP32-P4 Dev Kit

Ethernet

The ESP32-P4-WIFI6-DEV-KIT includes a 100 Mbps Ethernet port (RJ45) for wired network connectivity. Ethernet provides lower latency and more reliable throughput than WiFi, making it well-suited for industrial applications, IoT gateways, and any scenario where wired infrastructure is available.

Ethernet overview

Section titled “Ethernet overview”
SpecificationValue
Speed10/100 Mbps (Fast Ethernet)
ConnectorRJ45 with integrated magnetics and LEDs
PHYOnboard Ethernet PHY
Interface to ESP32-P4RMII

Hardware setup

Section titled “Hardware setup”

  1. Connect a standard Ethernet cable (Cat5e or better) between the board’s RJ45 port and your network switch or router.

  2. The RJ45 connector has two integrated LEDs:

    • Green: Link established
    • Yellow/amber: Network activity

  3. Verify the green LED illuminates after connecting the cable. If it does not, check the cable and the other end of the connection.

Ethernet setup (ESP-IDF)

Section titled “Ethernet setup (ESP-IDF)”

  1. Include the required headers:

    #include "esp_eth.h"
    #include "esp_netif.h"
    #include "esp_event.h"

  2. Initialize the network stack and Ethernet driver:

    void app_main(void)
    {
        esp_netif_init();
        esp_event_loop_create_default();
    

        // Create default Ethernet netif
        esp_netif_config_t cfg = ESP_NETIF_DEFAULT_ETH();
        esp_netif_t *eth_netif = esp_netif_new(&cfg);
    

        // Configure the Ethernet MAC and PHY
        eth_mac_config_t mac_config = ETH_MAC_DEFAULT_CONFIG();
        eth_phy_config_t phy_config = ETH_PHY_DEFAULT_CONFIG();
    

        // The PHY address and reset GPIO depend on board design
        phy_config.phy_addr = 1;
        phy_config.reset_gpio_num = -1;  // No dedicated reset pin
    

        esp_eth_mac_t *mac = esp_eth_mac_new_esp32(&mac_config);
        esp_eth_phy_t *phy = esp_eth_phy_new_ip101(&phy_config);
    

        esp_eth_config_t config = ETH_DEFAULT_CONFIG(mac, phy);
        esp_eth_handle_t eth_handle = NULL;
        esp_eth_driver_install(&config, &eth_handle);
    

        esp_netif_attach(eth_netif, esp_eth_new_netif_glue(eth_handle));
    

        // Register event handlers
        esp_event_handler_register(ETH_EVENT, ESP_EVENT_ANY_ID,
                                   &eth_event_handler, NULL);
        esp_event_handler_register(IP_EVENT, IP_EVENT_ETH_GOT_IP,
                                   &got_ip_event_handler, NULL);
    

        esp_eth_start(eth_handle);
    }

  3. Handle Ethernet events:

    static void eth_event_handler(void *arg, esp_event_base_t event_base,
                                  int32_t event_id, void *event_data)
    {
        switch (event_id) {
        case ETHERNET_EVENT_CONNECTED:
            printf("Ethernet link up\n");
            break;
        case ETHERNET_EVENT_DISCONNECTED:
            printf("Ethernet link down\n");
            break;
        case ETHERNET_EVENT_START:
            printf("Ethernet started\n");
            break;
        case ETHERNET_EVENT_STOP:
            printf("Ethernet stopped\n");
            break;
        }
    }
    

    static void got_ip_event_handler(void *arg, esp_event_base_t event_base,
                                     int32_t event_id, void *event_data)
    {
        ip_event_got_ip_t *event = (ip_event_got_ip_t *)event_data;
        printf("Ethernet got IP: " IPSTR "\n", IP2STR(&event->ip_info.ip));
    }

  4. Build and flash:

    Terminal window
    idf.py build
    idf.py -p /dev/ttyUSB0 flash monitor

    You should see DHCP address assignment in the serial output once the cable is connected.

Static IP configuration

Section titled “Static IP configuration”

If your network does not have a DHCP server, configure a static IP:

esp_netif_dhcpc_stop(eth_netif);


esp_netif_ip_info_t ip_info = {
    .ip.addr      = ESP_IP4TOADDR(192, 168, 1, 100),
    .gw.addr      = ESP_IP4TOADDR(192, 168, 1, 1),
    .netmask.addr = ESP_IP4TOADDR(255, 255, 255, 0),
};
esp_netif_set_ip_info(eth_netif, &ip_info);

Dual networking: Ethernet + WiFi

Section titled “Dual networking: Ethernet + WiFi”

The ESP32-P4 can run Ethernet and WiFi simultaneously, enabling gateway and bridge applications:

// Initialize both interfaces
esp_netif_t *eth_netif = esp_netif_new(&ESP_NETIF_DEFAULT_ETH());
esp_netif_t *wifi_netif = esp_netif_create_default_wifi_sta();


// Start both
esp_eth_start(eth_handle);
esp_wifi_start();


// Each interface gets its own IP address.
// Use routing configuration to control traffic flow.

Use cases

Section titled “Use cases”

IoT gateway

Bridge WiFi or BLE devices to a wired network. Ethernet provides a stable upstream while the C6 co-processor handles wireless clients.

Industrial automation

Connect to factory PLCs and SCADA systems over wired Ethernet. The deterministic latency of wired connections is critical for real-time control.

Network appliance

Build a protocol translator, data logger, or edge computing node that plugs directly into the network infrastructure.

Development and debugging

Use Ethernet for high-speed log streaming and firmware OTA updates, keeping WiFi free for the application.

Troubleshooting

Section titled “Troubleshooting”
SymptomCauseFix
Green LED not litNo link detectedCheck cable, try a different port on the switch
DHCP timeoutNetwork does not have DHCPConfigure a static IP address
esp_eth_driver_install returns errorWrong PHY driver selectedVerify the PHY model matches your board revision
Can ping locally but not externallyGateway not set correctlyCheck gateway address in DHCP or static config
Link flaps (up/down repeatedly)Bad cable or EMIReplace cable; move away from interference sources

Further reading

Section titled “Further reading”