LEDs blinking constantly at same rate

We have designed a product that uses the Digi Connect ME (DCME) to connect via Ethernet. The connections to the DCME are very simple:
3.3V (3.28V tested) to pin 15
GND to pin 16
Serial RXD to pin 7
All 4 mounting posts to GND.
All other pins left disconnected.

When the device is powered on, the green and yellow LEDs flash during diagnosics, then after a few seconds, both LEDs flash on and off at the same rate constantly. I assume this means there is an error although am unsure of what. Also, the device cannot be discovered using the device discovery utility.

Do any of the other pins need to be connected for the device to function? I would assume that the device only needs power and gnd to pins 15 and 16 to function; is this accurate? What do the flashing LEDs mean?

Thanks for any help you can offer.


Cameron should be the one to answer this, but here is my take on it:

The flashing LEDs are the diagnostic indication of the error. What is the pattern - nine blinks then one quick one, then a repeat?

How did you program the module? Did you use a development board to test the program first? If so, did you disable /dev/com1 before programming the non-JTAG module?

You didn’t mention it, but I assume that you also have TXD hooked up. You will need it to do diagnostics on the module using a terminal program.



The Amber (yellow) LED is the Ethernet link light and is directly connected to the Ethernet PHY. Under normal operating conditions there is no way that the Connect ME can effect the state of this LED. As for the Ethernet activity LED, it is used for diagnostics messaging during bootup and subsequently control is passed to the PHY for use as activity.

Is this occuring on our provided development board or a board of your design? If this is on your board can we test an ME module off of Digi’s board?

Are you seeing this flashing behavior when the ME is connected to a hub/switch?

Is it connected to a hub or switch?

If it is a switch, is the switch configured for auto detection? Can you reconfigure the ME’s port on that switch to manual and see what happens.

Has Erik has pointed out the error codes outputted on the activity LED are displayed in a three count pattern, i.e. 4-1-1, 9-1-1, etc. These patterns mean something and I can provide these codes meaning.

The fact that the link LED is also blinking would seem indicate that the problem is likely with the module or (if so mounted) with the board you designed.

I understand that you are already working with tech support, so I shall cut my comments off here.


Did you use pin 7 and 8 when the DCME was plugged into the Development board. I am wondering if these pins are able to be used on the board.


The following is a more detailed description of the LED flashing sequence with approximate timing:

Power on.
Yellow and Green ON - .25s
Green OFF - .25s
Yellow OFF - .25s
Repeat about 5 times.
Then Yellow and Green Flashing together rapidly and constantly until powered off.

The module does not have a custom program on it. It uses the default Digi firmware so I am assuming it is a hardware issue, not software.

Thanks for your help.