Kogna Ethernet issue when Konnect board is plugged in

[jtremel]

Hi Tom,

As you know, I am working on commissioning the new Kogna board.

I seam to have run into another problem that I can't resolve myself.

My testing to date has been with the Kogna board running without any of the expansion boards hooked up.
In all this time, I have not had a single connection / communication issue.

This morning, however, I tried to add a Konnect into the system and I couldn't establish a connection to the board.

Troubleshoot Procedure

(1) Power up Kogna without the Konnect plugged in -> Everything works great

(2) Remove power, tie Konnect into JP4 with ribbon cable & power up Kogna -> the Kogna powers up and LED46/47 flash as they always do during boot-up. However, Kmotion.exe will not connect to the board.

(3) Remove power, remove ribbon cable from JP4, power up Kogna -> board powers up and establishes communication without issue

(4) Repeat steps 2 & 3 above multiple times with repeated behavior
(5) Repeat steps 2 & 3 above with JP6 instead of JP4 - same behavior

(6) Replace Kogna with a Kflop (same Konnect, ribbon cable, power supply etc...) and the Kflop works just fine and I can toggle outputs and read input from Konnect board.

Observations

Without the Konnect in the system the RJ45 LEDs are:
Link: blinking, mostly yellow, sometimes green (note I am colorblind, so my colors might be off)
Activity: solid green

With the Konnect plugged in:
Link: blinking
Activity: off (1 quick flash on when the board is first powered up)

I am using a 5V/ 3 amp power supply connected to JR1

[TomKerekes]

Hi Jim,

My apologies this is a known problem with Kogna and Konnect. The issue is the older Konnects place an excessive capacitance on the Reset signal. The ribbon cable inductance combined with the capacitance results in the Reset signal rising in a non-monotonic manner which causes the Ethernet Transceiver to not reset properly.

The solution is to remove C25 from Konnect. Our newer Konnects have C25 removed. I assume this is an older Konnect?

Can you remove this Capacitor? If not please ask for an RMA number and we will remove it for you.

[jtremel]

C25 is populated on the Konnect board I am testing with.

I will go ahead and remove it (and I'll get some of the newer rev boards ordered).

Thanks for the quick response!

[jtremel]

Hi Tom - I just wanted to follow and let you know that I did remove C25 and that did correct the problem.

This new Kogna board is awesome. Really, really nice job!

Thanks Again!

[TomKerekes]

Hi Jim,

Thanks much for the kind and encouraging words. Consider leaving a review.