Other Parts Discussed in Thread: DP83869HM, , USB-2-MDIO, DP83869
BACKGROUND: I have recently successfully used the DP83869EVM to verify that the DP83869HM is suitable for use as an embedded media convertor in a new design. The DP83869HM will be used on-board a new PCB design to convert/adapt a PHY 4-wire 10/100Base-T/Tx interface to an SFP socket where we intend to use SGMII SFP module to provide fiber optic Ethernet link. We are currently in the process of making the design changes needed to add the DP83869HM into our PCB design. I am utilizing both the device data sheet and the EVM User's Guide as references for this design.
IMMEDIATE GOAL: I want to include in our prototype design the ability to access and utilize the Serial Management Interface (SMI) of the DP83869HM. The EVM includes an MSP430 Launchpad which can be used for USB-2-MDIO access & control of the DP83869's SMI. Since we currently do not intended to use the SMI in production, my intent is to only bring the required SMI I/O & reference pins to a small header on our prototype PCB design. The intent is to use the MSP Launchpad of the EVM to connect to this SMI header on the prototype design if and when needed for testing and troubleshooting.
DISCREPANCIES: The EVM User's Guide (at the top of page 10) incorrectly states "The DP83869EVM supports SMI through J2 using pin 26 for MDIO and 28 for MDC." J2 on the EVM is only a 3-pin header used for selecting LED used for LED_0. The correct connector and pins (found in EVM schematic) are J15, pin 4 (MDIO_F) and 6 (MDC_F). Also, there are no other details provided in the User's Guide on this interface or connector J15.
Can anyone please verify the above corrections?
Also, it is apparent that the 0 Ohm resistors (R76, 77, 78, & 82) are included to allow some variations on how the SMI interface to the DP83869 is utilized, however it does not seem to readilly support my intention of using the MSP Launchpad on the EVM with our prototype design PCB's SMI.
Removing 2 of the 4 resistors would allow isolation of either:
A. J15 from the MSP Launchpad controlled SMI - By removing R76 & R78; OR
B. MSP Launchpad from SMI controlled through J15 - By removing R77 & R82.
To configure EVM for using MSP Launchpad through J15 to connect to our prototype PCB's SMI, I would need to remove all 4 resistors and add connection jumpers to connect:
1. MDIO_F to MDIO_OB; and
2. MDC_F to MDC_OB.
If anyone could also verify the details above for my plan it would be very helpful. Thanks!
