Functional Description
www.ti.com
26.1.8.4 EMAC Boot Procedure
NOTE: See AM335x ARM Cortex-A8 Microprocessors (MPUs) Silicon Errata (literature number
SPRZ360) for limitations of EMAC booting.
26.1.8.4.1 Device Initialization
• EMAC boot uses the CPGMAC port 1 of the device.
• Supports connection to external Ethernet PHY using the MII, RMII, RGMII and MDIO pins, based on
SYSBOOT pin settings.
• Device uses EFUSE registers mac_id0_lo and mac_id0_hi in the control module for Ethernet MAC
address of the device.
• Device detects if the PHY is alive on the MDIO interface and
– Reads the STATUS register to check if Ethernet link is active
– Reads the CONTROL register to detect the auto-negotiated mode of operation
• Is the mode full-duplex or half duplex
• Speed of operation, 1000/100/10 Mbps. Link speed is determined by reading the Auto-
Negotiation Advertisement and Auto-Negotiation Link Partner Base Page Ability registers in the
external PHY. (Note: See Section 1.2, Silicon Revision Functional Differences and
Enhancements, for differences in operation based on AM335x silicon revision.)
– Waits for five seconds for auto negotiation to complete before timing out.
• ROM expects an external 50-MHz reference clock requirement when using RMII.
26.1.8.4.2 BOOTP (RFC 951)
The device then proceeds to obtain the IP and Boot information using BOOTP protocol. The device
prepares and broadcasts the BOOTP message that has the following information:
• Device MAC address in “chaddr” field – to uniquely identify the device to the server.
• “vender-class-identifier” option number 60 (RFC 1497, RFC 1533). Servers could use this information
to identify the device type. The value present is "AM335x ROM". (Note: See Section 1.2, Silicon
Revision Functional Differences and Enhancements, for differences in operation based on AM335x
silicon revision.)
• “Client-identifier” option number 61 (RFC 1497, RFC 1533). This has the ASIC-ID structure which
contains additional info for the device.
The device then expects a BOOTP response that provides the following information for the booting to
proceed
• Device IP address from “yiaddr” field
• Subnetmask from extended option 1 (RFC 1497, RFC 1533)
• Gateway IP from extended option number 3 (RFC 1497, RFC 1533) or from “giaddr” field of BOOTP
response.
• Boot image filename from “file” field
• TFTP server IP address from the “siaddr” field
Timeouts and retries:
• Exponentially increasing timeouts starting from 4s, doubling for each retry.
• 5 retries
4144
Initialization SPRUH73H–October 2011–Revised April 2013
Submit Documentation Feedback
Copyright © 2011–2013, Texas Instruments Incorporated
To Next Page
Loading...
Need help?
General
