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LAN7500-ABZJ: A Hi-Speed Ethernet Controller with Bridge Function

A hi-speed Ethernet controller can make all the difference in the speedy transmission of communication-related data. LAN7500-ABZJ’s hi-speed communication offers that and many other benefits.

In this article, you will discover some of the additional features of this Ethernet controller – with an emphasis on how the bridging function works.

Ethernet Controllers are a type of interface used to establish a connection between the endpoints. The process typically involves the use of diverse signaling or communication protocol methods.

Ethernet Controllers are also positioned as modules or devices inside a larger device. Through this positioning, the controllers help in managing the communication (including data transfer) between an Ethernet interface and the digital processor of a system.

The Data Transfer Process

At the core of the data transfer is the receipt and transmission/transfer of data to and from the local processing bus connection.

The data would also be extended by establish the compliance with the Ethernet Standard (IEEE 802.3).

Thereafter, the data would be further sent to the Ethernet bus.

In all of these, LAN7500-ABZJ’s Ethernet Controller helps in “controlling” or regulating data flow. Now, we are going to talk about some of the core features the controller has.

USB to Ethernet Connection


Ethernet Controllers function by creating a connection between the Ethernet interface and the supported devices.

LAN7500-ABZJ’s connection is done via the path created with the high-performance USB to Ethernet connection. The connection allows the LAN7500-ABZJ Ethernet Controller to establish connection to a USB, especially as the USB can be based on the USB 2.0 communication module.

Such a module paves the way for a USB 2.0 to up to 1000 Mbps to the Ethernet Controller. Besides, the basis on the internal USB 2.0 device controller also paves the way for a connection to the USB PHY. Through this device, it is possible to obtain a wide range of other supported functions, including Bulk-out USB Endpoints, Control, Bulk-in and Interrupt functions.

Fully Integrated Functions

A majority of the functions offered via LAN7500-ABZJ are integrated. These functions include but are not limited to EEPROM controller, up to Ethernet to MAC and PHY, a FIFO controller with up to 32 kilobytes of internal packet buffering and a Filtering Engine. It also includes the following:

  • TAP controller
  • Hi-Speed USB 2.0 device controller

Load Offsetting

Excessive load, especially on the host’s part could be limiting, in terms of the Ethernet Controller’s part.

LAN7500-ABZJ has enabled a host offloading function to reduce this. It supports a wide range of TCP/UDP/IP checksum offloads. These offloads are further used to cut down on the loads on the host, thereby, making it flexible.

Depending on the peripherals, the load offsetting process could differ. For example, the device is configured to validate the IP checksum and the UDT/TCP checksum. That is for the Ethernet receive frames.

On the other hand, the Ethernet transmitted frames are configured with the intent of calculating the IP checksum, as well as the UDT/TCP checksum.

If a larger load is to be offset, it would be imperative to activate the Large Send Offload (LSO). It is primarily used in offloading or cutting down on the larger loads on the host CPU.

The Function of the EEPROM Controller

The EEPROM Controller, also known as the EPC, is a dedicated external EEPROM used to store the default values of the MAC address and the USB descriptors.

The EEPROM Controller (EPC) supports up to nine (9) address bits, which are used for establishing connection to the device.

The controller also supports most of the Type 256/512-byte EEPROMs, with some examples being the:

  • 93C56
  • 93C66

There is a chance that the EEPROM Controller (EPC) might not be functioning optimally at all times. An example is when it is not properly detected. In that situation, the Host LAN Driver required to set the IEEE addresses.

Due to the system-level resetting, it may be impossible for the Host to function optimally. The EEPROM Controller (EPC) also aids this process by allowing the device to load the default values. This is on the condition that the EEPROM is properly configured.

In addition to preventing the Host from initiating USB transactions pending the completion of the default value transfer; the EEPROM Controller also permits the Host to read, write and delete the content of the Serial EEPROM.

The USB Device Controller Function

Asides from the EEPROM Controller (EPC), LAN7500-ABZJ also supports the USB Device Controller. This controller works with the Universal Serial Bus (USB) and packs a variety of features.

Below are some of the functionalities:

1. Multi-Duplex Capabilities

LAN7500-ABZJ supports multiple devices, which are the half-duplex and the full-duplex. Or the full-duplex, the focus is on the transmission of data or enabling of communication both ways; so that the receiver and the sender can communicate at once. The reverse is the case with the half-duplex architecture, which has to do with the one-way communication method.

By supporting these two duplex options, LAN7500-ABZJ’s USB Device Controller allows for the selection of any kind of duplex that aligns with the communication in view.

2. Support for Multiple Power Modes

LAN7500-ABZJ also supports several power modes, such as a variable voltage I/O supply up to 3.3 volts, various GPIOs (up to 12), and the support for the self-powered and bus-powered operations.

The USB Driver Controller also supports the following:

  • Integrated Ethernet PHY, such as link status change wake-up detection, auto-negotiation and HP Auto-MDIX support.
  • Support for four (4) endpoints
  • Flexible address filtering modes, such as inverse filtering, 33 exact matches (both the multicast and unicast); and promiscuous multicast and unicast modes.
  • Integrated Ethernet MAC and PHY
  • PME pin support
  • The controller also supports the HS (40 Mbps) and the FS (12 Mbps) modes.
  • Support for remote wakeup
  • Wakeup packet support, including magic pocket, perfect FA frame and wakeup frame. It also supports the IPv6 and the IPv4 TCP SYN.

Final Words

LAN7500-ABZJ is a high-speed USB to Ethernet Controller, with the capability of supporting up to 1000 Mbps of data transfer.