Analog Loopback uses the
echoed signals from the unterminated MDI and decodes these signals
in the Hybrid to return the data to the MAC.
Enable
Loopback
Write registers:
- 0x0868 = 0x085A
- 0x04DF = 0x0006
- 0x0016 = 0x0108
- 0x0802 = 0x4A47
- 0x001F = 0x4000
Enable data
generator/checker for MAC side
Write registers:
- 0x0619 = 0x1555
- 0x0624 = 0x55BF
Check incoming data
from MAC side
Data can also be checked
internally by reading registers 0x063C, 0x063D, 0x063E
Enable data
generator/checker for Cable side
Write registers:
- 0x0619 = 0x0557
- 0x0624 = 0x55BF
Check data for Cable
side
- Write
register 0x0620[1] = 1'b1
- Read
register 0x620
- Bit [7:0] = Number of errors bytes received
- Bit [8] = PRBS checker lock status on incoming
data (1'b1 indicates lock)
Repeat steps 1 and 2 to continuously check error status of
incoming data stream.
Other system
requirements
Data generate by the
internal PRBS is transmitted over the MDI and the MAC interface.