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EK-TM4C1294XL: Want to Change LAN LEDs from PF0/PF4 to PK4/PK6.

Forrest Erickson
Genius 4125 points
Part Number: EK-TM4C1294XL

Hello,

We are working with a custom PWA which though based on the TM4C1294 Launchpad has different connections for the LAN LEDs. They are connected to PK4/PK6.

Our firmware is based on the enet_s2e example.  I made what I think are the changes to the only code managing the LAN LEDs. The changes were in the pinout.c file and the lwip_task.c file.  See below.

On our LAN jack only the LED connected to PK6 is lighting. It comes on when there is a link and goes out when I remove the LAN cable. The other LED on PK4 never lights.

And.

I must be missing something.

  • 0
    Genius 4125 points

    I put oscilloscope probe on PK4 and saw that it was high (LED should be on). Then when I touched the probe accidentally shoring the current limit resistor to ground (when probing next to the shield on the LAN jack it is easy to do) the LED lit up. I found it was working all along.  It is green and not nearly as bright as the yellow. I was looking sideways at the rear of our device and could not see the faint light.   Looks like we might want to change the current limit resistor from 330 to something lower.   There is about 1.3 volts across the resistor so current is almost 4mA.

    Anyway I will mark this resolved.

  • 0 in reply to Forrest Erickson
    TI__Guru 72500 points

    Thank you for posting the resolution to this issue.