5 phy speed, 6 phy duplex mode, 7 phy mdi/mdix modes – Maxim Integrated 78Q8430 Software Driver User Manual
Page 41: Phy speed, Phy duplex mode, Phy mdi/mdix modes
UG_8430_004
78Q8430 Software Driver Development Guidelines
Rev. 1.0
41
STEP 1: Use procedure
to read the value of the MR0 register.
STEP 2: Set the MR0 Restart Auto-negotiation bit.
This bit is self-clearing.
STEP 3: Use procedure
to write the modified value back to the MR0 register.
7.5 PHY
Speed
Use the following procedure to set the PHY speed:
STEP 1: Use procedure
to read the value of the MR0 register.
STEP 2: Clear the MR0 Auto-negotiation Enable bit to disable auto-negotiation.
The speed cannot be set if auto-negotiation is enabled.
STEP 3: Modify the value of the MR0 Speed Selection bit.
Clear the Speed Selection bit for 10Mbps mode. Set the Speed Selection bit for 100Mbps mode.
STEP 4: Use procedure
to write the modified value back to the MR0 register.
When the link speed is set in this way, auto-negotiation is disabled and the PHY only operates in the
selected speed and selected duplex mode even when a new link is established.
7.6 PHY Duplex Mode
Use the following procedure to set the PHY duplex mode:
STEP 1: Use procedure
to read the value of the MR0 register.
STEP 2: Clear the MR0 Auto-negotiation Enable bit to disable auto-negotiation.
The duplex mode can not be set if auto-negotiation is enabled.
STEP 3: Modify the value of the MR0 Duplex Mode bit.
Set the Duplex Mode bit for full-duplex mode. Clear the Duplex Mode bit for half-duplex mode.
STEP 4: Use procedure 7.1 to write the modified value back to the MR0 register.
When the duplex mode is set in this way, auto-negotiation is disabled and the PHY only operates in the
selected duplex mode and selected speed even when a new link is established.
7.7 PHY MDI/MDIX Modes
Use the following procedure to set the PHY MDI/MDIX mode:
STEP 1: Use procedure 7.2 to read the value of the MR16 register.
STEP 2: Clear the MR16 Auto Polarity bit to disable auto polarity.
The MDI/MDIX mode can not be set if auto polarity is enabled.
STEP 3: Modify the value of the MR16 Reverse Polarity bit.
Clear the Reverse Polarity bit for MDI mode. Set the Reverse Polarity bit for MDIX mode.
STEP 4: Use procedure 7.1 to write the modified value back to the MR16 register.
When the polarity is set in this way, auto polarity is disabled and the PHY only operates in the
selected polarity even when a new link is established.