JLinkExe: can not connect to target (nRF51822 - G0 rev)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Tue, 30 Sep 2014 15:35:28 GMT

Haha, OK, I closed the original post then...

Thanks again ;)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nguyen Hoan Hoang — Tue, 30 Sep 2014 15:12:36 GMT

I can't mark it as answered. It said only the Author or moderator can. I am not the admin. I am a user like you :)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Tue, 30 Sep 2014 14:53:40 GMT

Sorry, I didn't see this comment. yes I did the test, you're apparently right, it's very likely that the CPUs are faulty.

Thanks again for your help !

Cedric

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Tue, 30 Sep 2014 02:30:50 GMT

Sorry for the late answer, I wanted to test everything. The PCB has 2 layers, you're right...

I'm not sure if you're an administrator, if yes, can you mark my last answer as "solving" the problem ? (I don't have enough points to do it)

Thanks again for your help ;)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nikita — Fri, 26 Sep 2014 09:49:30 GMT

Did you test this G0 chips with internal LDO regulator powered from 3V supply? Maybe they don't work at all.

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nguyen Hoan Hoang — Thu, 25 Sep 2014 00:40:05 GMT

I am very curious to know what could be wrong. Let me know how it goes with the new G0. If all fail then may be the PCB is marginal. You may add more ground plane area. May be avoid the SWDIO trace going under the Pulldown resistor of the SWCLK. How many layers is your PCB ? I assume it's a 2 layers.

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Wed, 24 Sep 2014 19:48:08 GMT

Hi all,

EDIT: We've been investigating for a few days, and finally found the problem, here are the last steps:

We unsoldered a G0 from a faulty board and placed a C0 instead, it works.
We then did the opposite (soldered the G0 CPU on the C0 board) but it doesn't work.
A few days later, we received a few new G0 from an official dealer and did the exchange:

http://youtu.be/Jt-F5_ef1pI

It works, so we can apparently assume that the CPUs of the new batch are faulty. We wonder if it's a common problem, the factory was really serious until now.

Has anyone had a similar problem ?

Thanks again so much for your suggestions to all of you !

Cedric ;)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Fri, 19 Sep 2014 22:30:41 GMT

Hi Testy, I don't have the E0 rev but on my C0 rev it works with ~1.8V.

...but my G0 board doesn't work with 3.3V nor with 1.8V ;(

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Fri, 19 Sep 2014 22:26:38 GMT

Hi Nikita, I just re-checked and I confirm, there is no DEC1 short in any of the G0 boards but the one of my friend works well even with 0V on DEC1.

About the DEC2 voltage I have 1.8V on both my G0 (faulty) and C0 (woking) boards.

Thanks a lot for your suggestions !

Cedric ;)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nikita — Wed, 17 Sep 2014 19:50:40 GMT

Try to check for short circuit between DEC1 and GND. DEC1 voltage should be 1.2V. I don't know how can another G0 device work with 0V on DEC1:

but we compared with another working G0 board and it's coherent

Also check DEC2 voltage.

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

testy — Wed, 17 Sep 2014 03:18:20 GMT

Target voltage down to 1,7V shouldn't be a problem in QFN48 with internal LDO regulator connection, using j-link EDU, hw 9.0. Also flashing of nRF51422 rev. E0 works at 1,7V (less than minimum operating voltage 1,8V!)

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RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Wed, 17 Sep 2014 02:15:42 GMT

Haha, you've been giving a lot of awesome ideas, that's just amazing... Do the CPU really need a crystal to be programmed by a Jlink probe ? (I didn't think) I'll publish the results as soon as I'll have checked all your suggestions ;) Thanks thanks thanks !!

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nguyen Hoan Hoang — Wed, 17 Sep 2014 02:09:39 GMT

Do you have a meeter that can beep on conductivity ? check the pcb trace if it reaches the pin. It could be a problem with the crystal too. Verify the crystal and the 2 capacitors. I am running out of ideas too :)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Wed, 17 Sep 2014 01:23:29 GMT

So you really confirm that if a GPIO is stuck to another one or to GNC/VCC, the probe might not be able to reset/flash the CPU ?

Wouldn't it be a very strange coincidence if all the 2nd batch boards had bad PCB / solder mask ? (their 1st batch was good and I didn't change the design)

I don't have the tools to unsolder the CPU so I guess I'll have to try with a pan. Would you have another trick to suggest ?

Thanks again and again !!

Cedric ;)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nguyen Hoan Hoang — Wed, 17 Sep 2014 00:56:08 GMT

Shorts does necessary means stuck at 0 or 1. Those are the case when it is shorted to gnu or vcc. You can also have 2 io lines shorted together. That would generate erratic results. Or could be open instead. Are you able to remove the G0 and place the C0 in its place. Might be a PCB issue.

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Tue, 16 Sep 2014 23:29:38 GMT

Shorts: would a GPIO stuck at 0 (or at 1) really be a problem to flash with the probe? (anyway, it would be very strange to have a short in all the new boards and in none of the previous batch)
SWC pull down: Nice catch, I didn't notice that there is a difference here! So I rechecked the PAN doc and I tried with a smaller resistance, then with no pull down, but it didn't work either...

Anyway, thanks a lot for your help!!!

Cedric ;)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nguyen Hoan Hoang — Tue, 16 Sep 2014 21:27:11 GMT

then there are only 2 things I can think of. Check if any shorts on those pins. Check also the pulldown resistor value, the one on the SWC. It's 10K on mine and work well both C0 & G0, except that it does not work with 1.8V.

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Cedric Honnet — Tue, 16 Sep 2014 15:58:06 GMT

Good point, I just tried the recover feature of nRFgoStudio with 3.3V and it didn't work.

Thanks a lot for your suggestion anyway!

Cedric ;)

RE: JLinkExe: can not connect to target (nRF51822 - G0 rev)

Nguyen Hoan Hoang — Tue, 16 Sep 2014 15:23:17 GMT

Try to power your board with at least 2V see if it makes any different. I have had expereneced situation when voltage drops below 2V, the jtag became intermittent.