VSC8221 Evaluation Board
VPPD-03471 VSC8221 User Guide Revision 1.0
8
1.
2.
3.
4.
5.
6.
4.4.2
CAT5 to SGMII with Modified Clause 37 AutoNeg Disabled
To configure the device for Clause 37 Auto-negotiation disabled, perform these steps:
Set up the copper Ethernet traffic source (e.g., IXIA or Smartbits).
Connect an Ethernet cable to an RJ-45.
Plug in a SFP loopback module.
Write 0xBA20 to “MII Register” (Port 0) Reg 23 (Extended PHY Control #1).
Write 0x9040 to “MII Register” (Port 0) Reg 0 (SW Reset for PHY Control setting to take effect).
Monitor the link-up bit in MII Register 1, bit 2 (MII 1.2), read twice to update. Traffic should now be
flowing.
4.5
Useful Registers
4.5.1
Ethernet Packet Generator
ExtMII 29E is the Ethernet Packet Generator register. Refer to datasheet for configuration options.
A bad-CRC counter is in ExtMII 23.7:0. This counter will be saturate at 0xFF and is cleared when read.
4.5.2
Far-End Loopback
When MII Register 23 bit 3 is set to 1, it forces incoming data from a link partner on the media side to be
retransmitted back to the link partner on the media interface.
4.5.3
Near-End Loopback
When MII Register 0 bit 14 is set to 1, the transmit data (TDP/TDN) on the MAC side is looped back onto
the receive data (RDP/RDN pins) to the MAC.
