Microchip Technology ATSAMA5D2-ICP User Manual page 29

3.2.8.3 1-Gbit Ethernet HSIC
The Microchip LAN7850 is a USB 2.0 Gigabit Ethernet Controller with HSIC interface. The LAN7850 supports
10Base/100Base-TC/1000Base-T Ethernet (full duplex support), is configured for operation through internal default
settings and supports custom configuration through the external 4-Kbit EEPROM device or interval one-time
programmable (OTP) memory.
The LAN7850 contains an integrated 10/100/1000 Ethernet MAC and PHY, Filtering Engine, USB PHY (with HSIC
interface), high-speed USB 2.0 device controller, TAP controller, EEPROM controller, and a FIFO controller with
internal packet buffering.
The Ethernet controller supports auto-negotiation, auto-polarity correction and HP Auto-MDIX, and is compliant with
the IEEE 802.3, IEEE 802.3u, IEEE 802.3ab, and 802.3az (Energy Efficient Ethernet) standards. ARP and NS offload
are also supported.
An internal EEPROM controller exists to load various USB and Ethernet configuration parameters. For EEPROM-less
applications, the LAN7850 provides 1 Kbyte of OTP memory that can be used to preload this same configuration data
before enumeration.
3.2.8.3.1 External EEPROM / Internal OTP
At power-up, the LAN7850 searches for an external EEPROM. If an external EEPROM (93AA66A) is detected, the
LAN7850 configuration is loaded from it. If no EEPROM is found, the device checks the OTP. If there is no OTP, the
device uses default CSR settings. The EEPROM stores the default values for the USB descriptors and the MAC
address.
3.2.8.3.2 Enable Link Status LEDs
When configured with the default internal register settings, the Ethernet link status LEDs are not enabled. To enable
those LEDs, enable the EEPROM.
Each LED is detailed below:
• Link1000: yellow LED (RJ45 J10) is ON with a valid 1000 Mbps link.
• Link100: green LED (RJ45 J10) is ON with a valid 100 Mbps link.
• Link/Act: RGB LED (LD5) is ON and green with network activity.
• Duplex/Collision: RGB LED (LD5) is ON and red in Full Duplex mode. LED is OFF in Half-Duplex mode. LED
blinks red during collision.
• Suspend: RGB LED (LD5) is ON and blue in Suspend mode.
3.2.8.3.3 External Chip Reset
When the Reset push button switch is pressed, the device places all pins into their default state and the entire
contents of the EEPROM or OTP are reloaded. An additional PIO (PC2) allows the LAN7850 to be reset by software.
The figure below illustrates the implementation of the Ethernet HSIC interface.
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2020 Microchip Technology Inc.
User Guide
ATSAMA5D2-ICP
Board Components
DS60001592A-page 29