why nRF51822 cannot connect to J-LINK?

RE: why nRF51822 cannot connect to J-LINK?

MartinBL — Tue, 20 Oct 2015 11:38:55 GMT

OK. Let us hope that will do the trick.

RE: why nRF51822 cannot connect to J-LINK?

sunnyjet16 — Tue, 20 Oct 2015 01:05:49 GMT

Hi Martin,

I asked SMT factory to produce 50 boards by SMT machine instead of manual soldering to if it has the same problems.

RE: why nRF51822 cannot connect to J-LINK?

MartinBL — Fri, 16 Oct 2015 10:34:35 GMT

Very strange. Did you have any more nRF51s to try? Could it be that they are damaged by ESD?

RE: why nRF51822 cannot connect to J-LINK?

sunnyjet16 — Thu, 15 Oct 2015 01:12:23 GMT

VDD is measured and it is 3.3V. As for connection, I tested the voltage of SWDIO is above 0.1V that means J1 connects to nRF51822. And the connection is measured by meter.

RE: why nRF51822 cannot connect to J-LINK?

MartinBL — Wed, 14 Oct 2015 08:49:33 GMT

Have you measured that the voltage Vdd is correct at 3.3V on the faulty boards?

Are you able to confirm that there is a proper connection between the SWD pins on your connector J1 and on your nRF51?

Do you have more chips to try? Again, I think it is strange that 4 out of 5 chips are faulty, but maybe they have all been subjected to some ESD conditions?

RE: why nRF51822 cannot connect to J-LINK?

sunnyjet16 — Wed, 14 Oct 2015 01:13:13 GMT

Hi Martin,

Actutally, all marked area is connected to ground through Via. It seems software issue that causes no via appeared when the layout file is transformed to PDF file. All the components are same on the 5 boards.

RE: why nRF51822 cannot connect to J-LINK?

MartinBL — Tue, 13 Oct 2015 08:44:27 GMT

It looks like you have a few isolated ground "islands" that is not connected to anything:

Maybe this is the cause? Are the top and bottom ground layers connected? We recommend using a lot of via holes connecting the ground planes. Especially around the antenna.

Are you using the exact same components on all boards?

On the four misbehaving boards are you measuring correct Vdd?

RE: why nRF51822 cannot connect to J-LINK?

sunnyjet16 — Tue, 13 Oct 2015 07:18:02 GMT

Thanks, Martin. My chip is nRF51822 QFAAH0 I put schematic and layout on the link: pan.baidu.com/.../1mgne2jm

RE: why nRF51822 cannot connect to J-LINK?

MartinBL — Mon, 12 Oct 2015 13:09:44 GMT

Yes. And this is important. The SWDIO pin is also an active low reset pin and should be pulled high (to Vdd) whenever you are not programming the chip. However, the pin has an internal ~13 kOhm pull up resistor so it should stay high unless you have connected anything to the pin externally. You could try to add an external pull up resistor of ~1kOhm, but even if this solves the problem it doesn't really explain why it happens.
Hard to say. It could very well be bad soldering or a bad circuit. I find it unlikely that 4 out of 5 chips are bad.

What chip revision do you have? Refer to the Compatibility matrix.

Could you upload your schematic and/or PCB layout? If you are not comfortable uploading it here you can create a MyPage account and submit a support ticket there. Then you will get private support and you can get a completely confidential review of your schematic/board.