Works OK on the DK, but not on my custom board (no radio) - NRF52832 wlcsp

[DJR]

Hi fellow devs:)
I'd really appreciate some advice on this please. I've come to a bit of a dead-end.
Hopefully you can spot a mistake I've made.

I am trying to produce a low cost mass producible device which basically measures temperature and broadcasts the beacon data at 1 sec intervals. Pretty simple...
Energy harvesting from a nearby induction field will charge 2 supercapacitors, which power-up the bluetooth chip.
The charging side of it works ok, but for my tests I am just using a bench power supply. I have designed a custom board, long and thin, only 5mm width. That's why I chose the small 3mm WL-CSP.

My application code works just fine on the DK, radio working, advertising works.
But it does not work on my custom board. I actually made 10 boards, and all of them have the same problem.

DK: NRF52832 QFN package. Both a 32MHz and 32.768KHz crystal.
My PCB: NRF52832 WL-CSP. Only 32MHz crystal mounted.

My custom board setup:
VDD-NRF: 3.0V
SWD: Programs OK via DK NRF-Programmer.
Application: Beacon, reporting temperature data.
Problem: No radio (Advertising not found in nrf connect phone app). 

Strange symptom with my custom boards:
Advertising is briefly noticed in the nrf connect app (with scanning mode running) only during programming. After programming, nothing is seen from the radio again.
I repeated this test and monitored brief bursts of activity on the 32MHz clock

 

    

Link to the Schematic PDF


And here is my Prj.conf

CONFIG_ADC=y
CONFIG_ADC_ASYNC=y
CONFIG_ADC_LOG_LEVEL_INF=y
CONFIG_ADC_NRFX_ADC_CHANNEL_COUNT=3

CONFIG_GPIO=y

# BLUETOOTH CONFIG
CONFIG_BT=y
CONFIG_BT_DEBUG_LOG=y
CONFIG_BT_DEVICE_NAME="Heatle-Rod"

# c library
CONFIG_NEWLIB_LIBC=y

# power management
#CONFIG_SYS_POWER_MANAGEMENT=y
#CONFIG_DEVICE_POWER_MANAGEMENT=y
#CONFIG_DEVICE_IDLE_PM=y

#CONFIG_SYS_POWER_MANAGEMENT=y
#CONFIG_SYS_POWER_SLEEP_STATES=y
#CONFIG_SYS_POWER_DEEP_SLEEP_STATES=y
#CONFIG_DEVICE_POWER_MANAGEMENT=y

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
#CONFIG_CLOCK_CONTROL_NRF_K32SRC_250PPM=y
#CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y
#CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_20PPM=y
CONFIG_SOC_SERIES_NRF52X=y
CONFIG_SOC_NRF52832_QFAA=y

The project C files are atatched here also.
sw-pcb-rod-ble-develop (1).zip



Kind regsrds,
David
Heatle.de

[Kaja]

Hi, 

from what I can see in the pdf of the gerber files:
1.You must follow the reference design
2. When designing a 2-layer pcb, you need to take have the bottom layer as mainly ground. See our guideline for nRF52805

3. There can't be any routing under the RF path and antenna, only ground under the RF path.
4. You need to properly ground the center pad.

Best regards,
Kaja

[Kenneth]

Hi, 

In addition to Kaja's comments, I would like to comment on this:

DJR said:

But the radio only works when in Debug Interface Mode.
Ie. Beacon seen on our cell phone (NRF connect App). Data received looks ok.

You have not followed the reference design, this can make the design unstable, if you attached a debugger this can improve the situation marginally, just enough to make it work.

Do you see any difference if you don't go to sleep (don't use idle_state_handle(), nrf_pwr_mgmt_run(), sd_app_evt_wait())?

Kenneth

[AnsgarSchmidt]

Hi Kenneth, 

please let me shortly introduce myself. I am working with David and helping with the software side of the project.
Thanks for the advice, I will give it a try. Just short summary of the current behavior:

Board without debugger at power on -> Nothing happens.
Board with debugger at power on, everything works, even when stopping the debugger.

We connected the reset pin and the behavior is like this:

Power on without Debugger + Reset -> Nothing happens
Power on with      Debugger + Reset -> Restarts instantly (with and without debugger running)

So it seems the debugger is somehow kickstarting the clocks or something.

I will give it a try with your recommendations and report back.

Greetings

Ansgar

[AnsgarSchmidt]

Hi Kenneth,

I removed all sleep routines and still the same behavior. The blinky example is also not working. Just for clarification, your software works fine on the nRF52 DK with the board set to 52805.

Greetings

Ansgar

[hmolesworth]

Perhaps try with all debug logging turned off, if not already tried ..