09-05-2011 08:25 AM
Here is a board designed by myself, the power supply and oscilator is normal ,but when i connect the cable,the mode led is not on, what's the problem? And another strange thing is ,the MDI pin has no output after power on.(In ML507 board the MDI has output ) .
09-05-2011 09:19 AM
This sounds like a pretty hard thing to debug over a web forum. There are a number of reasons
why you might not get link connection, especially on a new board design. For example, there
could be problems with the signal routing between the 88E1111 and the magnetics and jack.
If you have more than one board to try, you might find it is an assembly problem. Which package
is the 88E1111? Many of these are QFN style which can be hard to see if they are soldered
properly. What are you using for magnetics? Is it an integrated "mag/jack" or separate
transformer plus connector? Did you copy the design from an eval board schematic? If not
did you follow the recommendations of the chip and magnetics manufacturers? Did you
check all of the supply voltages to the 88E1111 and the magnetics? The more details you
provide, the better help you will receive.
09-05-2011 09:37 AM
Did you copy the design from an eval board schematic?
My favourite new-board-design method of shooting myself in the foot is: incorrect layout 'dolly' (i.e. board layout footprint).
Are there any components on this board design which have not been used before (e.g. RJ45 connector, e'net PHY, FPGA)? These are the likely candidates for unproven layout dollies.
-- Bob Elkind
09-05-2011 04:54 PM
If you've set sensible defaults using the configuration pins, the PHY should light up LEDs when you plug a cable in, even without programming any registers. Check the RESETn pin - it is active low, so you must hold it high during normal operation. If you hold the 88E1111 in reset, it will not light any of its status LEDs.
09-05-2011 07:46 PM
I'm really clear that it's a pretty hard thing to debug over a web forum. But i have spent over a week to solute this problem.So i have to post in the web forum.
The Ethernet chip package on my board is 128-PQFP, and i have tested all of the power and gnd pin ,all are normal (comparde with the ML507 board). but i want to make sure :
1、if the MDI have waveform ouput after power on .
2、 what's peak_to_peak value of the waveform?
3、if this waveform is used to synchronize with the RJ45?
09-05-2011 08:18 PM
First of all, what voltage level do you measure on your RESETn pin?
The MDI signals and levels will depend on the speed of your network (10/100/1000). You could refer to the appropriate standard (e.g. 802.3ab) for details about what to expect.
If the PHY is auto-negotiating properly, you should expect to see a clock on the RX_CLK output. If the PHY is running at all, you should see something on 125CLK.
09-06-2011 05:44 AM
If the PHY is running at all, you should see something on 125CLK.
Actually for the 88E1111, the 125CLK output can be disabled as a strapping option.
In fact the strapping resistors / connections are a good place to start looking for
differences between your design and the ML507.
09-06-2011 06:53 PM