NRF52832 (on BMD-350 Module) SWD not connecting...

[GJChristman]

I'm having no luck in getting JLinkExe or nrfjprog to see my BMD-350 device on my custom PCB. 

I have read though all the threads here that reference similar issues and have verified all of the following:

* Connections to SWCLK and SWDIO are made properly and have no pullup/pulldown resistors.

* The device is remotely powered

* The signals on SWCLK and SWDIO are there and look to be the proper levels.

* The device itself works - it has factory firmware that advertises services (RigDFU etc.) on BLE

I have tried both a Segger JLink as well as the using the development board programmer via the 10

pin connector.

There has to be something basic I am missing.  Below are a
PDF of the device schematic and the log.log output from nrfjprog -f nrf52 --recover

I'm doing the development in Linux, and have had no problem in connecting to the development board.

I've also asked for help from the manufacturer, UBlox, but have heard nothing back from them.

Any pointers here would be greatly appreciated.

-Glenn

6648.log.logSG_Bluetooth_4-Layer.pdf

[Jared]

Hi there,

The schematics looks ok. 

1. Exactly what voltage do you measure on VDD, GND and RESET pin?
2. Have you tried omitting the regulator stage and power the board directly from a bench top supply? 
3. Do you see this issue on all of your samples? 
4. Thank you for including the log from nrfjprog --recover. But could you also specify what error message that is reported by the program when you just run nrfjprog --recover? 

regards

Jared 

[GJChristman]

Hi Jared,

Thanks for responding.

 - The voltages on the board are:

   * VDD - 3.28V

   * GND - .009V

   * nRESET - 3.28V

Under test, I am powering the board over the SWD cable with a bench power supply into a 3.3V regulator. 

I've tried a couple of the BMD-350s, and they all seem to give the same results

One thing I noticed when looking at a couple schematics I found for the Thingy devices is that you use a 4.6 uF capacitor after the regulator - I have just a 1uF on my board.  I was going to try putting a 4.7uF in its place but have not yet done so.

I've attached the output from nrfjprog --recover:

Fullscreen nrfjprog_out.txt Download

ERROR: Unable to connect to a debugger.
ERROR: JLinkARM DLL reported an error. Try again. If error condition
ERROR: persists, run the same command again with argument --log, contact Nordic
ERROR: Semiconductor and provide the generated log.log file to them.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.

[hmolesworth]

Idle thought: Try disconnecting Batt_Sense. It will phantom power the BMD350 and prevent the hardware reset functioning properly (internal reset, not pin reset) on power up/down. The reason is the slow startup of the LDOs driving the load capacitance so VCC comes up after io pin has powered the die via internal schottky protection diodes.. as little as 1uA can do this ..

.. also does the op-amp have its power rails connected?

[GJChristman]

Interesting thoughts.  Yes, the OP-AMP is powered.  I can just pull that, and pull R7 as well as a test. 

The OP-AMP is going to have an output voltage as well, seeing as the bridge circuit is not complete.

Thanks again.

[GJChristman]

No joy

I pulled R7 and was able to lift a trace to disconnect the OP-AMP - neither seemed to have any effect.

Stubborn little bugger.

[GJChristman]

Just to share the misery, here are photos of what I've been talking about:

The whole setup:

The interface breadboard:

and the target...(yellow wire is scope connection on SWDIO)

[hmolesworth]

Quite sure about the colours? I see from the photo:

White  1 VDD
Yellow 2 SWDIO
Red    3 nRESET
Blue   4 SWCLK
Black  5 GND
(n/c)  6 SWO

TC2030-IDC-NL-Datasheet-Rev-B.pdf

[GJChristman]

Yes, Those are the proper colors - signal mappings. 

On the 10-pin connector, 3,5 and 9 are all tied to ground.