Problem with nRF52 DK

[Garth]

Hi all,

I just received my nRF52 DK and started attempting to run examples on it. I am having an odd trouble that the LED2 is always lit after programming the board, no matter the application. Additionally the LED4 is dimly lit. Does anyone have any clue what could be causing this? It is leading me to believe there may be more underlying issues with the rest of the board as well.

Thanks in advance!

[RK]

Read the anomaly about trace being activated when debug is activated. The trace pins, rather strangely I thought, are the same ones chosen for LED2 and LED4, LED2 is connected to the pin with trace data, so it's high, LED4 to the pin with trace clock, so it's 50% duty cycle lit.

The current SystemInit code turns trace off to work around that anomaly, unless you've defined the ENABLE_TRACE define, however that has to run after your debugger puts the chip into debug mode otherwise it has no effect and when the chip is later put into debug mode, the trace gets re-enabled and nothing turns it off again. I had to fix a property in my build environment (Crossworks) to get into debug mode before SystemInit.

And if you are defining the ENABLE_TRACE macro, then you're getting what you asked for, trace enabled, and those two LEDs are somewhat less useful.

[RK]

That's the fix which is working for me. You could also, annoying though it is, stick a breakpoint in SystemInit. Or else repeat the logic from there which turns trace off at the start of main.