Disable debug unit with JLink still connected?

[Christopher Mason]

I'm measuring current consumption on nRF51822, making code changes and then flashing/debugging via JLink GDBServer and gdb.

Right now it seems like I either have to physically disconnect my board from the JLink Lite or disconnect the JLink from USB after uploading the program. If I simply reset the chip, the debug unit stays enabled and I see ~1.5 mA current draw. Having to physically plug and unplug is a bit tedious.

Is there a way for me to disable the Segger and reset the chip such that when it resets, DEBUG is off and it does not draw the associated current? Preferably some way I can automate via a Makefile? I've tried switching to the JTAG interface via JLinkExe but that doesn't help.

Thanks!

-c

[Ulrich Myhre]

Hi,

Have you tried doing a PIN-reset by calling "nrfjprog -p"?

This should properly detach the debugger interface and reset the chip.

Regards, Ulrich

[Chris]

Could this be done through JLink GDB server?

[Christopher Mason]

I should also mention: I'm on a mac. Does the nrfjprog tool use the JLink DLL? Is it open source?

[Chris]

nrfjprog doesn't run on OSX, that is why I asked about JLink GDB Server. Not sure how nrfjprog actually does the reset, but we might be able to do it with the JLink console.

[Ulrich Myhre]

I'm on thin ice when it comes to GDB server in general, but take a look at Chapter 10.1.3 of the nRF51 reference manual. Pin-reset, power-on-reset or brown-out reset should all detach the debugger.

nrfjprog just follows the procedure listed in 10.1.3, using the JLink DLL.

1. Write 0x1 to POWER_RESET register
2. ClrTMS & ClrTCK
3. Wait at least 2ms
4. SetTMS

Hope this helps