Achronix Speedster22i 10G/40G/100G Ethernet - Manual (Page 55)

UG029, September 6, 2013 55
Control Register Bits (KXAN_CONTROL) through Next page Ability Register Bits (AN_XNP
/ LP_AN_XNP) for details).
Usage
After reset, auto-negotiation is disabled. To use it, the following steps would be typically
needed (as a suggestion) for a channel.
Figure 26: Auto negotiation Use Flow
Table 29 – Auto-Negotiation Usage
Step# Function
Related
Registers
Description
1
Initialize:
- Program
Ability Registers
- Clear Status
latches
KXAN_ABILITY0..2
KXAN_STATUS
Defines the base page abilities that are
exchanged first during autonegotiation.
Needs to be set according to the wanted
features before autonegotiation can be
enabled.
The status register should be read prior
to enabling autonegotiation to reset all
latches that may be active from a
previous use of the autonegotiation.
2
Enable
Autonegotiation
KXAN_CONTROL
Enable autonegotiation (bit12).
Here also the NextPage control (bit13)
must be set if next page exchanges are
wanted (i.e. local device needs to
transmit next page messages and has
set bit15 in AN_ABILITY0). Only after this
Start
Initialize
Autonegotiation
Done
Enable
Autonegotiation
Exchange
Next Page
Next
Page?
Yes
No/Done
Configure
PCS Layers
Reset
PCS Layers
AN_STATUS(page received)
W ait Base Page
Exchange
W ait Autoneg
completed
an_done +
AN_STATUS
AN_STATUS(page received)
Note: now the statemachine
enters AN_GOOD_CHECK
and updates
BP_ETH_STATUS