Добавил:
ИВТ (советую зайти в "Несортированное")rnПИН МАГА Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
interfeysy_1 / ИДЗ_машинка / даташиты / esp32_technical_reference_manual_en.pdf
Скачиваний:
19
Добавлен:
26.01.2024
Размер:
9.62 Mб
Скачать

10 Ethernet Media Access Controller (MAC)

10 Ethernet Media Access Controller (MAC)

10.1Overview

Features of Ethernet

By using the external Ethernet PHY (physical layer), ESP32 can send and receive data via Ethernet MAC (Media Access Controller) according to the IEEE 802.3 standard, as Figure 10-1 shows. Ethernet is currently the most commonly used network protocol that controls how data is transmitted over localand wide-area networks, abbreviated as LAN and WAN, respectively.

Figure 10­1. Ethernet MAC Functionality Overview

ESP32 MAC Ethernet complies with the following criteria:

IEEE 802.3-2002 for Ethernet MAC

Two industry-standard interfaces conforming with IEEE 802.3-2002: Media-Independent Interface (MII) and Reduced Media-Independent Interface (RMII).

Features of MAC Layer

Support for a data transmission rate of 10 Mbit/s or 100 Mbit/s through an external PHY interface

Communication with an external Fast Ethernet PHY through IEEE 802.3-compliant MII and RMII interfaces

Support for:

Carrier Sense Multiple Access / Collision Detection (CSMA/CD) protocol in half-duplex mode

IEEE 802.3x flow control in full-duplex mode

operations in full-duplex mode, forwarding the received pause-control frame to the user application

backpressure flow control in half-duplex mode

If the flow control input signal disappears during a full-duplex operation, a pause frame with zero pause time value is automatically transmitted.

The Preamble and the Start Frame Delimiter (SFD) are inserted in the Transmit path, and deleted in the Receive path.

Cyclic Redundancy Check (CRC) and Pad can be controlled on a per-frame basis.

Espressif Systems

221

ESP32 TRM (Version 5.0)

Submit Documentation Feedback

10Ethernet Media Access Controller (MAC)

The Pad is generated automatically, if data is below the minimum frame length.

Programmable frame length supporting jumbo frames of up to 16 KB

Programmable Inter-frame Gap (IFG) (40-96 bit times in steps of 8)

Support for a variety of flexible address filtering modes:

Up to eight 48-bit perfect address filters to mask each byte

Up to eight 48-bit SA address comparison checks to mask each byte

All multicast address frames can be transmitted

All frames in mixed mode can be transmitted without being filtered for network monitoring

A status report is attached each time all incoming packets are transmitted and filtered

Returning a 32-bit status for transmission and reception of packets respectively

Separate transmission, reception, and control interfaces for the application

Use of the Management Data Input/Output (MDIO) interface to configure and manage PHY devices

Support for the offloading of received IPv4 and TCP packets encapsulated by an Ethernet frame in the reception function

Support for checking IPv4 header checksums, as well as TCP, UDP, or ICMP (Internet Control Message Protocol) checksums encapsulated in IPv4/IPv6 packets in the enhanced reception function

Two sets of FIFOs: one 2 KB Tx FIFO with programmable threshold and one 2 KB Rx FIFO with configurable threshold (64 bytes by default)

When Rx FIFO stores multiple frames, the Receive Status Vector is inserted into the Rx FIFO after transmitting an EOF (end of frame), so that the Rx FIFO does not need to store the Receive Status of these frames.

In store-and-forward mode, all error frames can be filtered during reception, but not forwarded to the application.

Under-sized good frames can be forwarded.

Support for data statistics by generating pulses for lost or corrupted frames in the Rx FIFO due to an overflow

Support for store-and-forward mechanism when transmitting data to the MAC core

Automatic re-transmission of collided frames during transmission (subject to certain conditions, see section 10.2.1.2)

Discarding frames in cases of late collisions, excessive collisions, excessive deferrals, and under-run conditions

The Tx FIFO is flushed by software control.

Calculating the IPv4 header checksum, as well as the TCP, UDP, or ICMP checksum, and then inserting them into frames transmitted in store-and-forward mode.

Ethernet Block Diagram

Figure 10-2 shows the block diagram of the Ethernet.

Ethernet MAC consists of the MAC-layer configuration register module and three layers: EMAC_CORE (MAC Core Layer), EMAC_MTL (MAC Transition Layer), and EMAC_DMA (Direct Memory Access). Each of these three layers

Espressif Systems

222

ESP32 TRM (Version 5.0)

Submit Documentation Feedback

Соседние файлы в папке даташиты