Ethernet

[中文]

Overview

ESP-IDF provides a set of consistent and flexible APIs to support both internal Ethernet MAC (EMAC) controller and external SPI-Ethernet modules.

This programming guide is split into the following sections:

1. Basic Ethernet Concepts

2. Configure MAC and PHY

3. Connect Driver to TCP/IP Stack

4. Misc control of Ethernet driver

Basic Ethernet Concepts

Ethernet is an asynchronous Carrier Sense Multiple Access with Collision Detect (CSMA/CD) protocol/interface. It is generally not well suited for low power applications. However, with ubiquitous deployment, internet connectivity, high data rates and limitless rage expandability, Ethernet can accommodate nearly all wired communications.

Normal IEEE 802.3 compliant Ethernet frames are between 64 and 1518 bytes in length. They are made up of five or six different fields: a destination MAC address (DA), a source MAC address (SA), a type/length field, data payload, an optional padding field and a Cyclic Redundancy Check (CRC). Additionally, when transmitted on the Ethernet medium, a 7-byte preamble field and Start-of-Frame (SOF) delimiter byte are appended to the beginning of the Ethernet packet.

Thus the traffic on the twist-pair cabling will appear as shown blow:

Ethernet Data Frame Format

Preamble and Start-of-Frame Delimiter

The preamble contains seven bytes of 55H, it allows the receiver to lock onto the stream of data before the actual frame arrives. The Start-of-Frame Delimiter (SFD) is a binary sequence 10101011 (as seen on the physical medium). It is sometimes considered to be part of the preamble.

When transmitting and receiving data, the preamble and SFD bytes will automatically be generated or stripped from the packets.

Destination Address

The destination address field contains a 6-byte length MAC address of the device that the packet is directed to. If the Least Significant bit in the first byte of the MAC address is set, the address is a multi-cast destination. For example, 01-00-00-00-F0-00 and 33-45-67-89-AB-CD are multi-cast addresses, while 00-00-00-00-F0-00 and 32-45-67-89-AB-CD are not. Packets with multi-cast destination addresses are designed to arrive and be important to a selected group of Ethernet nodes. If the destination address field is the reserved multi-cast address, i.e. FF-FF-FF-FF-FF-FF, the packet is a broadcast packet and it will be directed to everyone sharing the network. If the Least Significant bit in the first byte of the MAC address is clear, the address is a uni-cast address and will be designed for usage by only the addressed node.

Normally the EMAC controller incorporates receive filters which can be used to discard or accept packets with multi-cast, broadcast and/or uni-cast destination addresses. When transmitting packets, the host controller is responsible for writing the desired destination address into the transmit buffer.

Source Address

The source address field contains a 6-byte length MAC address of the node which created the Ethernet packet. Users of Ethernet must generate a unique MAC address for each controller used. MAC addresses consist of two portions. The first three bytes are known as the Organizationally Unique Identifier (OUI). OUIs are distributed by the IEEE. The last three bytes are address bytes at the discretion of the company that purchased the OUI. More information about MAC Address used in ESP-IDF, please see MAC Address Allocation.

When transmitting packets, the assigned source MAC address must be written into the transmit buffer by the host controller.

Type / Length

The type/length field is a 2-byte field, if the value in this field is <= 1500 (decimal), it is considered a length field and it specifies the amount of non-padding data which follows in the data field. If the value is >= 1536, it represents the protocol the following packet data belongs to. The following are the most common type values:

• IPv4 = 0800H

• IPv6 = 86DDH

• ARP = 0806H

Users implementing proprietary networks may choose to treat this field as a length field, while applications implementing protocols such as the Internet Protocol (IP) or Address Resolution Protocol (ARP), should program this field with the appropriate type defined by the protocol’s specification when transmitting packets.

Payload

The payload field is a variable length field, anywhere from 0 to 1500 bytes. Larger data packets will violate Ethernet standards and will be dropped by most Ethernet nodes. This field contains the client data, such as an IP datagram.

Padding and FCS

The padding field is a variable length field added to meet IEEE 802.3 specification requirements when small data payloads are used. The DA, SA, type, payload and padding of an Ethernet packet must be no smaller than 60 bytes. Adding the required 4-byte FCS field, packets must be no smaller than 64 bytes. If the data field is less than 46 bytes long, a padding field is required.

The FCS field is a 4-byte field which contains an industry standard 32-bit CRC calculated with the data from the DA, SA, type, payload and padding fields. Given the complexity of calculating a CRC, the hardware normally will automatically generate a valid CRC and transmit it. Otherwise, the host controller must generate the CRC and place it in the transmit buffer.

Normally, the host controller does not need to concern itself with padding and the CRC which the hardware EMAC will also be able to automatically generate when transmitting and verify when receiving. However, the padding and CRC fields will be written into the receive buffer when packets arrive, so they may be evaluated by the host controller if needed.

Note

Besides the basic data frame described above, there’re two other common frame types in 10/100 Mbps Ethernet: control frames and VLAN tagged frames. They’re not supported in ESP-IDF.

Configure MAC and PHY

Ethernet driver is composed of two parts: MAC and PHY. The communication between MAC and PHY can have diverse choices: MII (Media Independent Interface), RMII (Reduced Media Independent Interface) and etc.

Ethernet RMII Interface

One of the obvious difference between MII and RMII is the signal consumption. For MII, it usually costs up to 18 signals. Instead, RMII interface can reduce the consumption to 9.

In RMII mode, both the receiver and transmitter signals are referenced to the REF_CLK. REF_CLK must be stable during any access to PHY and MAC. Generally there’re three ways to generate the REF_CLK depending on the PHY device in your design:

• Some PHY chip can derive the REF_CLK from its external connected 25MHz crystal oscillator (as seen the option a in the picture). In this case, you should select CONFIG_ETH_RMII_CLK_INPUT in CONFIG_ETH_RMII_CLK_MODE.

• Some PHY chip uses an external connected 50MHz crystal oscillator or other clock source, which can also be used as the REF_CLK for MAC side (as seen the option b in the picture). In this case, you still need to select CONFIG_ETH_RMII_CLK_INPUT in CONFIG_ETH_RMII_CLK_MODE.

• Some EMAC controller can generate the REF_CLK using its internal high precision PLL (as seen the option c in the picture). In this case, you should select CONFIG_ETH_RMII_CLK_OUTPUT in CONFIG_ETH_RMII_CLK_MODE.

Warning

If the RMII clock mode is selected to CONFIG_ETH_RMII_CLK_OUTPUT, then GPIO0 can be used to output the REF_CLK signal. See CONFIG_ETH_RMII_CLK_OUTPUT_GPIO0 for more information. What’s more, if you’re not using PSRAM in your design, GPIO16 and GPIO17 are also available to output the reference clock. See CONFIG_ETH_RMII_CLK_OUT_GPIO for more information.

If the RMII clock mode is selected to CONFIG_ETH_RMII_CLK_INPUT, then GPIO0 is the only choice to input the REF_CLK signal. Please note that, GPIO0 is also an important strapping GPIO on ESP32. If GPIO0 samples a low level during power up, ESP32 will go into download mode. The system will get halted until a manually reset. The workaround of this issue is disabling the REF_CLK in hardware by default, so that the strapping pin won’t be interfered by other signals in boot stage. Then re-enable the REF_CLK in Ethernet driver installation stage. The ways to disable the REF_CLK signal can be:

• Disable or power down the crystal oscillator (as the case b in the picture).

• Force the PHY device in reset status (as the case a in the picture). This could fail for some PHY device (i.e. it still outputs signal to GPIO0 even in reset state).

No matter which RMII clock mode you select, you really need to take care of the signal integrity of REF_CLK in your hardware design! Keep the trace as short as possible. Keep it away from RF devices. Keep it away from inductor elements.

Note

ESP-IDF only supports the RMII interface (i.e. always select CONFIG_ETH_PHY_INTERFACE_RMII in Kconfig option CONFIG_ETH_PHY_INTERFACE).

Signals used in data plane are fixed to specific GPIOs via MUX, they can’t be modified to other GPIOs. Signals used in control plane can be routed to any free GPIOs via Matrix. Please refer to ESP32-Ethernet-Kit for hardware design example.

We need to setup necessary parameters for MAC and PHY respectively based on your Ethernet board design and then combine the two together, completing the driver installation.

Configuration for MAC is described in eth_mac_config_t, including:

• sw_reset_timeout_ms: software reset timeout value, in milliseconds, typically MAC reset should be finished within 100ms.

• rx_task_stack_size and rx_task_prio: the MAC driver creates a dedicated task to process incoming packets, these two parameters are used to set the stack size and priority of the task.

• smi_mdc_gpio_num and smi_mdio_gpio_num: the GPIO number used to connect the SMI signals.

• flags: specifying extra features that the MAC driver should have, it could be useful in some special situations. The value of this field can be OR’d with macros prefixed with ETH_MAC_FLAG_. For example, if the MAC driver should work when cache is disabled, then you should configure this field with ETH_MAC_FLAG_WORK_WITH_CACHE_DISABLE.

Configuration for PHY is described in eth_phy_config_t, including:

• phy_addr: multiple PHY device can share the same SMI bus, so each PHY needs a unique address. Usually this address is configured during hardware design by pulling up/down some PHY strapping pins. You can set the value from 0 to 15 based on your Ethernet board. Especially, if the SMI bus is shared by only one PHY device, setting this value to -1 can enable the driver to detect the PHY address automatically.

• reset_timeout_ms: reset timeout value, in milliseconds, typically PHY reset should be finished within 100ms.

• autonego_timeout_ms: auto-negotiation timeout value, in milliseconds. Ethernet driver will start negotiation with the peer Ethernet node automatically, to determine to duplex and speed mode. This value usually depends on the ability of the PHY device on your board.

• reset_gpio_num: if your board also connect the PHY reset pin to one of the GPIO, then set it here. Otherwise, set this field to -1.

ESP-IDF provides a default configuration for MAC and PHY in macro ETH_MAC_DEFAULT_CONFIG and ETH_PHY_DEFAULT_CONFIG.

Create MAC and PHY Instance

Ethernet driver is implemented in an Object-Oriented style. Any operation on MAC and PHY should be based on the instance of them two.

eth_mac_config_t mac_config = ETH_MAC_DEFAULT_CONFIG();  // apply default MAC configuration
mac_config.smi_mdc_gpio_num = 23;  // alter the GPIO used for MDC signal
mac_config.smi_mdio_gpio_num = 18; // alter the GPIO used for MDIO signal
esp_eth_mac_t *mac = esp_eth_mac_new_esp32(&mac_config); // create MAC instance

eth_phy_config_t phy_config = ETH_PHY_DEFAULT_CONFIG(); // apply default PHY configuration
phy_config.phy_addr = 1;       // alter the PHY address according to your board design
phy_config.reset_gpio_num = 5; // alter the GPIO used for PHY reset
esp_eth_phy_t *phy = esp_eth_phy_new_ip101(&phy_config); // create PHY instance
// ESP-IDF officially supports several different Ethernet PHY
// esp_eth_phy_t *phy = esp_eth_phy_new_rtl8201(&phy_config);
// esp_eth_phy_t *phy = esp_eth_phy_new_lan8720(&phy_config);
// esp_eth_phy_t *phy = esp_eth_phy_new_dp83848(&phy_config);

Note

Care should be taken, when creating MAC and PHY instance for SPI-Ethernet modules (e.g. DM9051), the constructor function must have the same suffix (e.g. esp_eth_mac_new_dm9051 and esp_eth_phy_new_dm9051). This is because we don’t have other choices but the integrated PHY. Besides that, we have to create an SPI device handle firstly and then pass it to the MAC constructor function. More instructions on creating SPI device handle, please refer to SPI Master.

Install Driver

Ethernet driver also includes event-driven model, which will send useful and important event to user space. We need to initialize the event loop before installing the Ethernet driver. For more information about event-driven programming, please refer to ESP Event.

/** Event handler for Ethernet events */
static void eth_event_handler(void *arg, esp_event_base_t event_base,
                              int32_t event_id, void *event_data)
{
    uint8_t mac_addr[6] = {0};
    /* we can get the ethernet driver handle from event data */
    esp_eth_handle_t eth_handle = *(esp_eth_handle_t *)event_data;

    switch (event_id) {
    case ETHERNET_EVENT_CONNECTED:
        esp_eth_ioctl(eth_handle, ETH_CMD_G_MAC_ADDR, mac_addr);
        ESP_LOGI(TAG, "Ethernet Link Up");
        ESP_LOGI(TAG, "Ethernet HW Addr %02x:%02x:%02x:%02x:%02x:%02x",
                 mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
        break;
    case ETHERNET_EVENT_DISCONNECTED:
        ESP_LOGI(TAG, "Ethernet Link Down");
        break;
    case ETHERNET_EVENT_START:
        ESP_LOGI(TAG, "Ethernet Started");
        break;
    case ETHERNET_EVENT_STOP:
        ESP_LOGI(TAG, "Ethernet Stopped");
        break;
    default:
        break;
    }
}

esp_event_loop_create_default(); // create a default event loop that running in background
esp_event_handler_register(ETH_EVENT, ESP_EVENT_ANY_ID, &eth_event_handler, NULL); // register Ethernet event handler (to deal with user specific stuffs when event like link up/down happened)

To install the Ethernet driver, we need to combine the instance of MAC and PHY and set some additional high-level configurations (i.e. not specific to either MAC or PHY) in esp_eth_config_t:

• mac: instance that created from MAC generator (e.g. esp_eth_mac_new_esp32()).

• phy: instance that created from PHY generator (e.g. esp_eth_phy_new_ip101()).

• check_link_period_ms: Ethernet driver starts an OS timer to check the link status periodically, this field is used to set the interval, in milliseconds.

• stack_input: In most of Ethernet IoT applications, any Ethernet frame that received by driver should be passed to upper layer (e.g. TCP/IP stack). This field is set to a function which is responsible to deal with the incoming frames. You can even update this field at runtime via function esp_eth_update_input_path() after driver installation.

• on_lowlevel_init_done and on_lowlevel_deinit_done: These two fields are used to specify the hooks which get invoked when low level hardware has been initialized or de-initialized.

ESP-IDF provides a default configuration for driver installation in macro ETH_DEFAULT_CONFIG.

esp_eth_config_t config = ETH_DEFAULT_CONFIG(mac, phy); // apply default driver configuration
esp_eth_handle_t eth_handle = NULL; // after driver installed, we will get the handle of the driver
esp_eth_driver_install(&config, &eth_handle); // install driver

Start Ethernet Driver

After driver installation, we can start Ethernet immediately.

esp_eth_start(eth_handle); // start Ethernet driver state machine

Connect Driver to TCP/IP Stack

Up until now, we have installed the Ethernet driver. From the view of OSI (Open System Interconnection), we’re still on level 2 (i.e. Data Link Layer). We can detect link up and down event, we can gain MAC address in user space, but we can’t obtain IP address, let alone send HTTP request. The TCP/IP stack used in ESP-IDF is called LwIP, for more information about it, please refer to LwIP.

To connect Ethernet driver to TCP/IP stack, these three steps need to follow:

1. Create network interface for Ethernet driver

2. Register IP event handlers

3. Attach the network interface to Ethernet driver

More information about network interface, please refer to Network Interface.

/** Event handler for IP_EVENT_ETH_GOT_IP */
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;
    const esp_netif_ip_info_t *ip_info = &event->ip_info;

    ESP_LOGI(TAG, "Ethernet Got IP Address");
    ESP_LOGI(TAG, "~~~~~~~~~~~");
    ESP_LOGI(TAG, "ETHIP:" IPSTR, IP2STR(&ip_info->ip));
    ESP_LOGI(TAG, "ETHMASK:" IPSTR, IP2STR(&ip_info->netmask));
    ESP_LOGI(TAG, "ETHGW:" IPSTR, IP2STR(&ip_info->gw));
    ESP_LOGI(TAG, "~~~~~~~~~~~");
}

esp_netif_init()); // Initialize TCP/IP network interface (should be called only once in application)
esp_netif_config_t cfg = ESP_NETIF_DEFAULT_ETH(); // apply default network interface configuration for Ethernet
esp_netif_t *eth_netif = esp_netif_new(&cfg); // create network interface for Ethernet driver
esp_eth_set_default_handlers(eth_netif); // set default handlers to process TCP/IP stuffs
esp_event_handler_register(IP_EVENT, IP_EVENT_ETH_GOT_IP, &got_ip_event_handler, NULL); // register user defined IP event handlers

esp_netif_attach(eth_netif, esp_eth_new_netif_glue(eth_handle)); // attach Ethernet driver to TCP/IP stack
esp_eth_start(eth_handle); // start Ethernet driver state machine

Warning

User’s Ethernet/IP event handlers need to be registered after registration of default handlers (i.e. after esp_eth_set_default_handlers()). General recommendation is to fully initialize Ethernet driver and network interface prior registering user’s Ethernet/IP event handlers, i.e. register the user event handlers as the last thing prior starting the Ethernet driver. Such approach ensures that Ethernet/IP events get executed first by the Ethernet driver or network interface and so the system is in expected state when executing user’s handlers.

Misc control of Ethernet driver

The following functions should only be invoked after the Ethernet driver has been installed.

• Stop Ethernet driver: esp_eth_stop()

• Update Ethernet data input path: esp_eth_update_input_path()

• Misc get/set of Ethernet driver attributes: esp_eth_ioctl()

/* get MAC address */
uint8_t mac_addr[6];
memset(mac_addr, 0, sizeof(mac_addr));
esp_eth_ioctl(eth_handle, ETH_CMD_G_MAC_ADDR, mac_addr);
ESP_LOGI(TAG, "Ethernet MAC Address: %02x:%02x:%02x:%02x:%02x:%02x",
         mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);

/* get PHY address */
int phy_addr = -1;
esp_eth_ioctl(eth_handle, ETH_CMD_G_PHY_ADDR, &phy_addr);
ESP_LOGI(TAG, "Ethernet PHY Address: %d", phy_addr);

Flow control

Ethernet on MCU usually has a limitation in the number of frames it can handle during network congestion, because of the limitation in RAM size. A sending station might be transmitting data faster than the peer end can accept it. Ethernet flow control mechanism allows the receiving node to signal the sender requesting suspension of transmissions until the receiver catches up. The magic behind that is the pause frame, which was defined in IEEE 802.3x.

Pause frame is a special Ethernet frame used to carry the pause command, whose EtherType field is 0x8808, with the Control opcode set to 0x0001. Only stations configured for full-duplex operation may send pause frames. When a station wishes to pause the other end of a link, it sends a pause frame to the 48-bit reserved multicast address of 01-80-C2-00-00-01. The pause frame also includes the period of pause time being requested, in the form of a two-byte integer, ranging from 0 to 65535.

After Ethernet driver installation, the flow control feature is disabled by default. You can enable it by invoking esp_eth_ioctl(eth_handle, ETH_CMD_S_FLOW_CTRL, true);. One thing should be kept in mind, is that the pause frame ability will be advertised to peer end by PHY during auto negotiation. Ethernet driver sends pause frame only when both sides of the link support it.

Application Example

• Ethernet basic example: ethernet/basic.

• Ethernet iperf example: ethernet/iperf.

• Ethernet to Wi-Fi AP “router”: ethernet/eth2ap.

• Most of protocol examples should also work for Ethernet: protocols.

API Reference

Header File

• esp_eth/include/esp_eth.h

Functions

esp_err_t esp_eth_driver_install(const esp_eth_config_t *config, esp_eth_handle_t *out_hdl)

Install Ethernet driver.

Return

• ESP_OK: install esp_eth driver successfully

• ESP_ERR_INVALID_ARG: install esp_eth driver failed because of some invalid argument

• ESP_ERR_NO_MEM: install esp_eth driver failed because there’s no memory for driver

• ESP_FAIL: install esp_eth driver failed because some other error occurred

Parameters

• [in] config: configuration of the Ethernet driver

• [out] out_hdl: handle of Ethernet driver

esp_err_t esp_eth_driver_uninstall(esp_eth_handle_t hdl)

Uninstall Ethernet driver.

Note

It’s not recommended to uninstall Ethernet driver unless it won’t get used any more in application code. To uninstall Ethernet driver, you have to make sure, all references to the driver are released. Ethernet driver can only be uninstalled successfully when reference counter equals to one.

Return

• ESP_OK: uninstall esp_eth driver successfully

• ESP_ERR_INVALID_ARG: uninstall esp_eth driver failed because of some invalid argument

• ESP_ERR_INVALID_STATE: uninstall esp_eth driver failed because it has more than one reference

• ESP_FAIL: uninstall esp_eth driver failed because some other error occurred

Parameters

• [in] hdl: handle of Ethernet driver

esp_err_t esp_eth_start(esp_eth_handle_t hdl)

Start Ethernet driver ONLY in standalone mode (i.e. without TCP/IP stack)

Note

This API will start driver state machine and internal software timer (for checking link status).

Return

• ESP_OK: start esp_eth driver successfully

• ESP_ERR_INVALID_ARG: start esp_eth driver failed because of some invalid argument

• ESP_ERR_INVALID_STATE: start esp_eth driver failed because driver has started already

• ESP_FAIL: start esp_eth driver failed because some other error occurred

Parameters

• [in] hdl: handle of Ethernet driver

esp_err_t esp_eth_stop(esp_eth_handle_t hdl)

Stop Ethernet driver.

Note

This function does the oppsite operation of esp_eth_start.

Return

• ESP_OK: stop esp_eth driver successfully

• ESP_ERR_INVALID_ARG: stop esp_eth driver failed because of some invalid argument

• ESP_ERR_INVALID_STATE: stop esp_eth driver failed because driver has not started yet

• ESP_FAIL: stop esp_eth driver failed because some other error occurred

Parameters

• [in] hdl: handle of Ethernet driver

esp_err_t esp_eth_update_input_path(esp_eth_handle_t hdl, esp_err_t (*stack_input)(esp_eth_handle_t hdl, uint8_t *buffer, uint32_t length, void *priv), void *priv, )

Update Ethernet data input path (i.e. specify where to pass the input buffer)

Note

After install driver, Ethernet still don’t know where to deliver the input buffer. In fact, this API registers a callback function which get invoked when Ethernet received new packets.

Return

• ESP_OK: update input path successfully

• ESP_ERR_INVALID_ARG: update input path failed because of some invalid argument

• ESP_FAIL: update input path failed because some other error occurred

Parameters

• [in] hdl: handle of Ethernet driver

• [in] stack_input: function pointer, which does the actual process on incoming packets

• [in] priv: private resource, which gets passed to stack_input callback without any modification

esp_err_t esp_eth_transmit(esp_eth_handle_t hdl, void *buf, size_t length)

General Transmit.

Return

• ESP_OK: transmit frame buffer successfully

• ESP_ERR_INVALID_ARG: transmit frame buffer failed because of some invalid argument

• ESP_FAIL: transmit frame buffer failed because some other error occurred

Parameters

• [in] hdl: handle of Ethernet driver

• [in] buf: buffer of the packet to transfer

• [in] length: length of the buffer to transfer

esp_err_t esp_eth_receive(esp_eth_handle_t hdl, uint8_t *buf, uint32_t *length)

General Receive is deprecated and shall not be accessed from app code, as polling is not supported by Ethernet.

Note

Before this function got invoked, the value of “length” should set by user, equals the size of buffer. After the function returned, the value of “length” means the real length of received data.

Note

This API was exposed by accident, users should not use this API in their applications. Ethernet driver is interrupt driven, and doesn’t support polling mode. Instead, users should register input callback with esp_eth_update_input_path.

Return

• ESP_OK: receive frame buffer successfully

• ESP_ERR_INVALID_ARG: receive frame buffer failed because of some invalid argument

• ESP_ERR_INVALID_SIZE: input buffer size is not enough to hold the incoming data. in this case, value of returned “length” indicates the real size of incoming data.

• ESP_FAIL: receive frame buffer failed because some other error occurred

Parameters

• [in] hdl: handle of Ethernet driver

• [out] buf: buffer to preserve the received packet

• [out] length: length of the received packet

esp_err_t esp_eth_ioctl(esp_eth_handle_t hdl, esp_eth_io_cmd_t cmd, void *data)

Misc IO function of Etherent driver.

Return

• ESP_OK: process io command successfully

• ESP_ERR_INVALID_ARG: process io command failed because of some invalid argument

• ESP_FAIL: process io command failed because some other error occurred

Parameters

• [in] hdl: handle of Ethernet driver

• [in] cmd: IO control command

• [in] data: specificed data for command

esp_err_t esp_eth_increase_reference(esp_eth_handle_t hdl)

Increase Ethernet driver reference.

Note

Ethernet driver handle can be obtained by os timer, netif, etc. It’s dangerous when thread A is using Ethernet but thread B uninstall the driver. Using reference counter can prevent such risk, but care should be taken, when you obtain Ethernet driver, this API must be invoked so that the driver won’t be uninstalled during your using time.

Return

• ESP_OK: increase reference successfully

• ESP_ERR_INVALID_ARG: increase reference failed because of some invalid argument

Parameters

• [in] hdl: handle of Ethernet driver

esp_err_t esp_eth_decrease_reference(esp_eth_handle_t hdl)

Decrease Ethernet driver reference.

Return

• ESP_OK: increase reference successfully

• ESP_ERR_INVALID_ARG: increase reference failed because of some invalid argument

Parameters

• [in] hdl: handle of Ethernet driver

Structures

struct esp_eth_config_t

Configuration of Ethernet driver.

Public Members

esp_eth_mac_t *mac

Ethernet MAC object.

esp_eth_phy_t *phy

Ethernet PHY object.

uint32_t check_link_period_ms

Period time of checking Ethernet link status.

esp_err_t (*stack_input)(esp_eth_handle_t eth_handle, uint8_t *buffer, uint32_t length, void *priv)

Input frame buffer to user’s stack.

Return

• ESP_OK: input frame buffer to upper stack successfully

• ESP_FAIL: error occurred when inputting buffer to upper stack

Parameters

• [in] eth_handle: handle of Ethernet driver

• [in] buffer: frame buffer that will get input to upper stack

• [in] length: length of the frame buffer

esp_err_t (*on_lowlevel_init_done)(esp_eth_handle_t eth_handle)

Callback function invoked when lowlevel initialization is finished.

Return

• ESP_OK: process extra lowlevel initialization successfully

• ESP_FAIL: error occurred when processing extra lowlevel initialization

Parameters

• [in] eth_handle: handle of Ethernet driver

esp_err_t (*on_lowlevel_deinit_done)(esp_eth_handle_t eth_handle)

Callback function invoked when lowlevel deinitialization is finished.

Return

• ESP_OK: process extra lowlevel deinitialization successfully

• ESP_FAIL: error occurred when processing extra lowlevel deinitialization

Parameters

• [in] eth_handle: handle of Ethernet driver

Macros

ETH_DEFAULT_CONFIG(emac, ephy)

Default configuration for Ethernet driver.

Type Definitions

typedef void *esp_eth_handle_t

Handle of Ethernet driver.

Header File

• esp_eth/include/esp_eth_com.h

Functions

esp_err_t esp_eth_detect_phy_addr(esp_eth_mediator_t *eth, int *detected_addr)

Detect PHY address.

Return

• ESP_OK: detect phy address successfully

• ESP_ERR_INVALID_ARG: invalid parameter

• ESP_ERR_NOT_FOUND: can’t detect any PHY device

• ESP_FAIL: detect phy address failed because some error occurred

Parameters

• [in] eth: mediator of Ethernet driver

• [out] detected_addr: a valid address after detection

Structures

struct esp_eth_mediator_s

Ethernet mediator.

Public Members

esp_err_t (*phy_reg_read)(esp_eth_mediator_t *eth, uint32_t phy_addr, uint32_t phy_reg, uint32_t *reg_value)

Read PHY register.

Return

• ESP_OK: read PHY register successfully

• ESP_FAIL: read PHY register failed because some error occurred

Parameters

• [in] eth: mediator of Ethernet driver

• [in] phy_addr: PHY Chip address (0~31)

• [in] phy_reg: PHY register index code

• [out] reg_value: PHY register value

esp_err_t (*phy_reg_write)(esp_eth_mediator_t *eth, uint32_t phy_addr, uint32_t phy_reg, uint32_t reg_value)

Write PHY register.

Return

• ESP_OK: write PHY register successfully

• ESP_FAIL: write PHY register failed because some error occurred

Parameters

• [in] eth: mediator of Ethernet driver

• [in] phy_addr: PHY Chip address (0~31)

• [in] phy_reg: PHY register index code

• [in] reg_value: PHY register value

esp_err_t (*stack_input)(esp_eth_mediator_t *eth, uint8_t *buffer, uint32_t length)

Deliver packet to upper stack.

Return

• ESP_OK: deliver packet to upper stack successfully

• ESP_FAIL: deliver packet failed because some error occurred

Parameters

• [in] eth: mediator of Ethernet driver

• [in] buffer: packet buffer

• [in] length: length of the packet

esp_err_t (*on_state_changed)(esp_eth_mediator_t *eth, esp_eth_state_t state, void *args)

Callback on Ethernet state changed.

Return

• ESP_OK: process the new state successfully

• ESP_FAIL: process the new state failed because some error occurred

Parameters

• [in] eth: mediator of Ethernet driver

• [in] state: new state

• [in] args: optional argument for the new state

Macros

ETH_MAX_PAYLOAD_LEN

Maximum Ethernet payload size.

ETH_MIN_PAYLOAD_LEN

Minimum Ethernet payload size.

ETH_HEADER_LEN

Ethernet frame header size: Dest addr(6 Bytes) + Src addr(6 Bytes) + length/type(2 Bytes)

ETH_CRC_LEN

Ethernet frame CRC length.

ETH_VLAN_TAG_LEN

Optional 802.1q VLAN Tag length.

ETH_JUMBO_FRAME_PAYLOAD_LEN

Jumbo frame payload size.

ETH_MAX_PACKET_SIZE

Maximum frame size (1522 Bytes)

ETH_MIN_PACKET_SIZE

Minimum frame size (64 Bytes)

Type Definitions

typedef struct esp_eth_mediator_s esp_eth_mediator_t

Ethernet mediator.

Enumerations

enum esp_eth_state_t

Ethernet driver state.

Values:

ETH_STATE_LLINIT

Lowlevel init done

ETH_STATE_DEINIT

Deinit done

ETH_STATE_LINK

Link status changed

ETH_STATE_SPEED

Speed updated

ETH_STATE_DUPLEX

Duplex updated

ETH_STATE_PAUSE

Pause ability updated

enum esp_eth_io_cmd_t

Command list for ioctl API.

Values:

ETH_CMD_G_MAC_ADDR

Get MAC address

ETH_CMD_S_MAC_ADDR

Set MAC address

ETH_CMD_G_PHY_ADDR

Get PHY address

ETH_CMD_S_PHY_ADDR

Set PHY address

ETH_CMD_G_SPEED

Get Speed

ETH_CMD_S_PROMISCUOUS

Set promiscuous mode

ETH_CMD_S_FLOW_CTRL

Set flow control

ETH_CMD_G_DUPLEX_MODE

Get Duplex mode

enum eth_link_t

Ethernet link status.

Values:

ETH_LINK_UP

Ethernet link is up

ETH_LINK_DOWN

Ethernet link is down

enum eth_speed_t

Ethernet speed.

Values:

ETH_SPEED_10M

Ethernet speed is 10Mbps

ETH_SPEED_100M

Ethernet speed is 100Mbps

enum eth_duplex_t

Ethernet duplex mode.

Values:

ETH_DUPLEX_HALF

Ethernet is in half duplex

ETH_DUPLEX_FULL

Ethernet is in full duplex

enum eth_event_t

Ethernet event declarations.

Values:

ETHERNET_EVENT_START

Ethernet driver start

ETHERNET_EVENT_STOP

Ethernet driver stop

ETHERNET_EVENT_CONNECTED

Ethernet got a valid link

ETHERNET_EVENT_DISCONNECTED

Ethernet lost a valid link

Header File

• esp_eth/include/esp_eth_mac.h

Functions

esp_eth_mac_t *esp_eth_mac_new_esp32(const eth_mac_config_t *config)

Create ESP32 Ethernet MAC instance.

Return

• instance: create MAC instance successfully

• NULL: create MAC instance failed because some error occurred

Parameters

• config: Ethernet MAC configuration

Structures

struct esp_eth_mac_s

Ethernet MAC.

Public Members

esp_err_t (*set_mediator)(esp_eth_mac_t *mac, esp_eth_mediator_t *eth)

Set mediator for Ethernet MAC.

Return

• ESP_OK: set mediator for Ethernet MAC successfully

• ESP_ERR_INVALID_ARG: set mediator for Ethernet MAC failed because of invalid argument

Parameters

• [in] mac: Ethernet MAC instance

• [in] eth: Ethernet mediator

esp_err_t (*init)(esp_eth_mac_t *mac)

Initialize Ethernet MAC.

Return

• ESP_OK: initialize Ethernet MAC successfully

• ESP_ERR_TIMEOUT: initialize Ethernet MAC failed because of timeout

• ESP_FAIL: initialize Ethernet MAC failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

esp_err_t (*deinit)(esp_eth_mac_t *mac)

Deinitialize Ethernet MAC.

Return

• ESP_OK: deinitialize Ethernet MAC successfully

• ESP_FAIL: deinitialize Ethernet MAC failed because some error occurred

Parameters

• [in] mac: Ethernet MAC instance

esp_err_t (*start)(esp_eth_mac_t *mac)

Start Ethernet MAC.

Return

• ESP_OK: start Ethernet MAC successfully

• ESP_FAIL: start Ethernet MAC failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

esp_err_t (*stop)(esp_eth_mac_t *mac)

Stop Ethernet MAC.

Return

• ESP_OK: stop Ethernet MAC successfully

• ESP_FAIL: stop Ethernet MAC failed because some error occurred

Parameters

• [in] mac: Ethernet MAC instance

esp_err_t (*transmit)(esp_eth_mac_t *mac, uint8_t *buf, uint32_t length)

Transmit packet from Ethernet MAC.

Return

• ESP_OK: transmit packet successfully

• ESP_ERR_INVALID_ARG: transmit packet failed because of invalid argument

• ESP_ERR_INVALID_STATE: transmit packet failed because of wrong state of MAC

• ESP_FAIL: transmit packet failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] buf: packet buffer to transmit

• [in] length: length of packet

esp_err_t (*receive)(esp_eth_mac_t *mac, uint8_t *buf, uint32_t *length)

Receive packet from Ethernet MAC.

Note

Memory of buf is allocated in the Layer2, make sure it get free after process.

Note

Before this function got invoked, the value of “length” should set by user, equals the size of buffer. After the function returned, the value of “length” means the real length of received data.

Return

• ESP_OK: receive packet successfully

• ESP_ERR_INVALID_ARG: receive packet failed because of invalid argument

• ESP_ERR_INVALID_SIZE: input buffer size is not enough to hold the incoming data. in this case, value of returned “length” indicates the real size of incoming data.

• ESP_FAIL: receive packet failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [out] buf: packet buffer which will preserve the received frame

• [out] length: length of the received packet

esp_err_t (*read_phy_reg)(esp_eth_mac_t *mac, uint32_t phy_addr, uint32_t phy_reg, uint32_t *reg_value)

Read PHY register.

Return

• ESP_OK: read PHY register successfully

• ESP_ERR_INVALID_ARG: read PHY register failed because of invalid argument

• ESP_ERR_INVALID_STATE: read PHY register failed because of wrong state of MAC

• ESP_ERR_TIMEOUT: read PHY register failed because of timeout

• ESP_FAIL: read PHY register failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] phy_addr: PHY chip address (0~31)

• [in] phy_reg: PHY register index code

• [out] reg_value: PHY register value

esp_err_t (*write_phy_reg)(esp_eth_mac_t *mac, uint32_t phy_addr, uint32_t phy_reg, uint32_t reg_value)

Write PHY register.

Return

• ESP_OK: write PHY register successfully

• ESP_ERR_INVALID_STATE: write PHY register failed because of wrong state of MAC

• ESP_ERR_TIMEOUT: write PHY register failed because of timeout

• ESP_FAIL: write PHY register failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] phy_addr: PHY chip address (0~31)

• [in] phy_reg: PHY register index code

• [in] reg_value: PHY register value

esp_err_t (*set_addr)(esp_eth_mac_t *mac, uint8_t *addr)

Set MAC address.

Return

• ESP_OK: set MAC address successfully

• ESP_ERR_INVALID_ARG: set MAC address failed because of invalid argument

• ESP_FAIL: set MAC address failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] addr: MAC address

esp_err_t (*get_addr)(esp_eth_mac_t *mac, uint8_t *addr)

Get MAC address.

Return

• ESP_OK: get MAC address successfully

• ESP_ERR_INVALID_ARG: get MAC address failed because of invalid argument

• ESP_FAIL: get MAC address failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [out] addr: MAC address

esp_err_t (*set_speed)(esp_eth_mac_t *mac, eth_speed_t speed)

Set speed of MAC.

Return

• ESP_OK: set MAC speed successfully

• ESP_ERR_INVALID_ARG: set MAC speed failed because of invalid argument

• ESP_FAIL: set MAC speed failed because some other error occurred

Parameters

• [in] ma:c: Ethernet MAC instance

• [in] speed: MAC speed

esp_err_t (*set_duplex)(esp_eth_mac_t *mac, eth_duplex_t duplex)

Set duplex mode of MAC.

Return

• ESP_OK: set MAC duplex mode successfully

• ESP_ERR_INVALID_ARG: set MAC duplex failed because of invalid argument

• ESP_FAIL: set MAC duplex failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] duplex: MAC duplex

esp_err_t (*set_link)(esp_eth_mac_t *mac, eth_link_t link)

Set link status of MAC.

Return

• ESP_OK: set link status successfully

• ESP_ERR_INVALID_ARG: set link status failed because of invalid argument

• ESP_FAIL: set link status failed because some other error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] link: Link status

esp_err_t (*set_promiscuous)(esp_eth_mac_t *mac, bool enable)

Set promiscuous of MAC.

Return

• ESP_OK: set promiscuous mode successfully

• ESP_FAIL: set promiscuous mode failed because some error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] enable: set true to enable promiscuous mode; set false to disable promiscuous mode

esp_err_t (*enable_flow_ctrl)(esp_eth_mac_t *mac, bool enable)

Enable flow control on MAC layer or not.

Return

• ESP_OK: set flow control successfully

• ESP_FAIL: set flow control failed because some error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] enable: set true to enable flow control; set false to disable flow control

esp_err_t (*set_peer_pause_ability)(esp_eth_mac_t *mac, uint32_t ability)

Set the PAUSE ability of peer node.

Return

• ESP_OK: set peer pause ability successfully

• ESP_FAIL: set peer pause ability failed because some error occurred

Parameters

• [in] mac: Ethernet MAC instance

• [in] ability: zero indicates that pause function is supported by link partner; non-zero indicates that pause function is not supported by link partner

esp_err_t (*del)(esp_eth_mac_t *mac)

Free memory of Ethernet MAC.

Return

• ESP_OK: free Ethernet MAC instance successfully

• ESP_FAIL: free Ethernet MAC instance failed because some error occurred

Parameters

• [in] mac: Ethernet MAC instance

struct eth_mac_config_t

Configuration of Ethernet MAC object.

Public Members

uint32_t sw_reset_timeout_ms

Software reset timeout value (Unit: ms)

uint32_t rx_task_stack_size

Stack size of the receive task

uint32_t rx_task_prio

Priority of the receive task

int smi_mdc_gpio_num

SMI MDC GPIO number, set to -1 could bypass the SMI GPIO configuration

int smi_mdio_gpio_num

SMI MDIO GPIO number, set to -1 could bypass the SMI GPIO configuration

uint32_t flags

Flags that specify extra capability for mac driver

Macros

ETH_MAC_FLAG_WORK_WITH_CACHE_DISABLE

MAC driver can work when cache is disabled

ETH_MAC_FLAG_PIN_TO_CORE

Pin MAC task to the CPU core where driver installation happened

ETH_MAC_DEFAULT_CONFIG()

Default configuration for Ethernet MAC object.

Type Definitions

typedef struct esp_eth_mac_s esp_eth_mac_t

Ethernet MAC.

Header File

• esp_eth/include/esp_eth_phy.h

Functions

esp_eth_phy_t *esp_eth_phy_new_ip101(const eth_phy_config_t *config)

Create a PHY instance of IP101.

Return

• instance: create PHY instance successfully

• NULL: create PHY instance failed because some error occurred

Parameters

• [in] config: configuration of PHY

esp_eth_phy_t *esp_eth_phy_new_rtl8201(const eth_phy_config_t *config)

Create a PHY instance of RTL8201.

Return

• instance: create PHY instance successfully

• NULL: create PHY instance failed because some error occurred

Parameters

• [in] config: configuration of PHY

esp_eth_phy_t *esp_eth_phy_new_lan8720(const eth_phy_config_t *config)

Create a PHY instance of LAN8720.

Return

• instance: create PHY instance successfully

• NULL: create PHY instance failed because some error occurred

Parameters

• [in] config: configuration of PHY

esp_eth_phy_t *esp_eth_phy_new_dp83848(const eth_phy_config_t *config)

Create a PHY instance of DP83848.

Return

• instance: create PHY instance successfully

• NULL: create PHY instance failed because some error occurred

Parameters

• [in] config: configuration of PHY

esp_eth_phy_t *esp_eth_phy_new_ksz8041(const eth_phy_config_t *config)

Create a PHY instance of KSZ8041.

Return

• instance: create PHY instance successfully

• NULL: create PHY instance failed because some error occurred

Parameters

• [in] config: configuration of PHY

Structures

struct esp_eth_phy_s

Ethernet PHY.

Public Members

esp_err_t (*set_mediator)(esp_eth_phy_t *phy, esp_eth_mediator_t *mediator)

Set mediator for PHY.

Return

• ESP_OK: set mediator for Ethernet PHY instance successfully

• ESP_ERR_INVALID_ARG: set mediator for Ethernet PHY instance failed because of some invalid arguments

Parameters

• [in] phy: Ethernet PHY instance

• [in] mediator: mediator of Ethernet driver

esp_err_t (*reset)(esp_eth_phy_t *phy)

Software Reset Ethernet PHY.

Return

• ESP_OK: reset Ethernet PHY successfully

• ESP_FAIL: reset Ethernet PHY failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

esp_err_t (*reset_hw)(esp_eth_phy_t *phy)

Hardware Reset Ethernet PHY.

Note

Hardware reset is mostly done by pull down and up PHY’s nRST pin

Return

• ESP_OK: reset Ethernet PHY successfully

• ESP_FAIL: reset Ethernet PHY failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

esp_err_t (*init)(esp_eth_phy_t *phy)

Initialize Ethernet PHY.

Return

• ESP_OK: initialize Ethernet PHY successfully

• ESP_FAIL: initialize Ethernet PHY failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

esp_err_t (*deinit)(esp_eth_phy_t *phy)

Deinitialize Ethernet PHY.

Return

• ESP_OK: deinitialize Ethernet PHY successfully

• ESP_FAIL: deinitialize Ethernet PHY failed because some error occurred

Parameters

• [in] phyL: Ethernet PHY instance

esp_err_t (*negotiate)(esp_eth_phy_t *phy)

Start auto negotiation.

Return

• ESP_OK: restart auto negotiation successfully

• ESP_FAIL: restart auto negotiation failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

esp_err_t (*get_link)(esp_eth_phy_t *phy)

Get Ethernet PHY link status.

Return

• ESP_OK: get Ethernet PHY link status successfully

• ESP_FAIL: get Ethernet PHY link status failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

esp_err_t (*pwrctl)(esp_eth_phy_t *phy, bool enable)

Power control of Ethernet PHY.

Return

• ESP_OK: control Ethernet PHY power successfully

• ESP_FAIL: control Ethernet PHY power failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

• [in] enable: set true to power on Ethernet PHY; ser false to power off Ethernet PHY

esp_err_t (*set_addr)(esp_eth_phy_t *phy, uint32_t addr)

Set PHY chip address.

Return

• ESP_OK: set Ethernet PHY address successfully

• ESP_FAIL: set Ethernet PHY address failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

• [in] addr: PHY chip address

esp_err_t (*get_addr)(esp_eth_phy_t *phy, uint32_t *addr)

Get PHY chip address.

Return

• ESP_OK: get Ethernet PHY address successfully

• ESP_ERR_INVALID_ARG: get Ethernet PHY address failed because of invalid argument

Parameters

• [in] phy: Ethernet PHY instance

• [out] addr: PHY chip address

esp_err_t (*advertise_pause_ability)(esp_eth_phy_t *phy, uint32_t ability)

Advertise pause function supported by MAC layer.

Return

• ESP_OK: Advertise pause ability successfully

• ESP_ERR_INVALID_ARG: Advertise pause ability failed because of invalid argument

Parameters

• [in] phy: Ethernet PHY instance

• [out] addr: Pause ability

esp_err_t (*del)(esp_eth_phy_t *phy)

Free memory of Ethernet PHY instance.

Return

• ESP_OK: free PHY instance successfully

• ESP_FAIL: free PHY instance failed because some error occurred

Parameters

• [in] phy: Ethernet PHY instance

struct eth_phy_config_t

Ethernet PHY configuration.

Public Members

int32_t phy_addr

PHY address, set -1 to enable PHY address detection at initialization stage

uint32_t reset_timeout_ms

Reset timeout value (Unit: ms)

uint32_t autonego_timeout_ms

Auto-negotiation timeout value (Unit: ms)

int reset_gpio_num

Reset GPIO number, -1 means no hardware reset

Macros

ESP_ETH_PHY_ADDR_AUTO

ETH_PHY_DEFAULT_CONFIG()

Default configuration for Ethernet PHY object.

Type Definitions

typedef struct esp_eth_phy_s esp_eth_phy_t

Ethernet PHY.

Header File

• esp_eth/include/esp_eth_netif_glue.h

Functions

void *esp_eth_new_netif_glue(esp_eth_handle_t eth_hdl)

Create a netif glue for Ethernet driver.

Note

netif glue is used to attach io driver to TCP/IP netif

Return

glue object, which inherits esp_netif_driver_base_t

Parameters

• eth_hdl: Ethernet driver handle

esp_err_t esp_eth_del_netif_glue(void *glue)

Delete netif glue of Ethernet driver.

Return

-ESP_OK: delete netif glue successfully

Parameters

• glue: netif glue

esp_err_t esp_eth_set_default_handlers(void *esp_netif)

Register default IP layer handlers for Ethernet.

Note

: Ethernet handle might not yet properly initialized when setting up these default handlers

Return

• ESP_ERR_INVALID_ARG: invalid parameter (esp_netif is NULL)

• ESP_OK: set default IP layer handlers successfully

• others: other failure occurred during register esp_event handler

Parameters

• [in] esp_netif: esp network interface handle created for Ethernet driver

esp_err_t esp_eth_clear_default_handlers(void *esp_netif)

Unregister default IP layer handlers for Ethernet.

Return

• ESP_ERR_INVALID_ARG: invalid parameter (esp_netif is NULL)

• ESP_OK: clear default IP layer handlers successfully

• others: other failure occurred during unregister esp_event handler

Parameters

• [in] esp_netif: esp network interface handle created for Ethernet driver

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