Part Number: DP83848C
I have designed the custom Ethernet board as like:
1) host computer : MPC860 / NXP
2) Ethernet PHY : DP83848C
- MAC Interface Mode : 10Mb SNI Mode
In Link-off condition, ping from MPC860 to other PC is OK,
but after Link-off and Link-on again,then MPC860 does not send TX signal normally.
To analysis the fault condition, I measured TX_CLK signal in DP83848C.
In normal condition, link-up, TX_CLK is 10MHz.
After that when link is changed into Link-off, TX_CLK is changed to 25MHz.
So TX_CLK, 25MHz, is asserted into MPC 860 that is set into speed 10Mbps.
Is it correct operation in SNI Mode of DP83848C ?
What happens when the link is established again after the reset? Does the TX_CLK go back to 10 MHz.
"After that when link is changed into Link-off, TX_CLK is changed to 25MHz." How is this happening, could you elaborate?
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In reply to Vibhu Vanjari:
Board configuration is like:
MPC860 -- DP83848I -- Transformer -- Ethernet Connector - PC
DP83848I is set to 10Mb SNI Mode (MII_MODE = 1, SNI_MODE = 1)
The value of TX_CLK output is changed by DP83848I Link State itself.
When DP83848I is Link-On state (Ethernet Connector is connected with PC), TX_CLK output is 10MHz.
If DP83848I is Link-Off state (Ethernet Connector is disconnected with PC), TX_CLK output is 25MHz always.
Your question: What happens when the link is established again after the reset? Does the TX_CLK go back to 10 MHz.
Yes, TX_CLK goes back to 10MHz because of Link state of DP83848I is On.
In reply to Gyu Youn Song1:
Thanks for answering my question. Can you please check the register status when connector is disconnected to see if the PHY is still in SNI mode?
In custom board, 3 Ethernet ports are needed.
So DP83848I MDC/MDIO is not connected into CPU MPC860 because of lack of available pin in MPC860.
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