Can not find the device

[nine-fox]

Hi,

I am working on a custom design for NRF52832. The schematic and pcb layout are as follows. However, it seems that I can not get the signal working correctly. Would you please take a look and give me some tips/advices/suggestions? Thank you very much.

The custom board is just for a small keyboard which is space limited. For testing, I am using pcb antenna only. I soldered 2 boards and both of them have the same problem:

1. Use SWD to burn softdevice and hrs sample(removed the external LFCLKSRC and turned on RTT logging)

2. It doesn't show in nRF connect/toolbox

3. I tried other samples like hid_keyboard, still the same problem: It doesn't show in nRF connect/toolbox/iOS/android.

4. No any errors prompt in RTT logger.

I suspect this is a pcb antenna design issue. However, by reading a lot from infocenter, still I can not find what the problem is. Should I solder a shunt capacitor in C76?

According to the guideline here: devzone.nordicsemi.com/.../ I am using:

1. X7 = 32M crystal, load cap = 10pF

2. C79=C78 = 16pF

3. nRF52832-QFAA, 2 layers, 1.6mm thickness, and FR-4 dielectric.

4. To avoid side effects, all other components like LEDs are not soldered in my testing boards.

(Left side is Back copper layer and right side is the Silk layer)

My Dev environment: Windows 10, Jlink 5.12f, SDK 13.0.0. Please let me know if you need further information. Thanks very much.

Yours sincerely,

Vincent

[nine-fox]

Hi endnode, thanks for your comments. May I ask, is it ok? My current pcb antenna layout design? RK mentioned that RF is connected to GND. However, I tried to use a knife to cut that line connecting to GND. The problem still exists.

If nothing wrong in my current design, I am considering to re-buy all my electronic components and try again. I suspect some parameters of capacitors or else are not well-matched with the ones Nordic suggests

[RK]

I doubt that, even if your components were a little wrong you'd get some radiation you could pick up . And connecting the antenna to ground is most definitely wrong. Connected to ground it's a wire, you need an antenna to radiate it has to be open-ended, balanced and tuned. I'm not entirely sure where you got that antenna design from, it seems a little long to me, but I'm not an expert in F-antennae. Normally somewhere around here either AbystomaLabs or one of the Nordic guys jumps in, they're quite good at this, I just know that connecting an antenna to ground is wrong. Do you actually have your antenna connected to the ANT pin? If so what component connects it? I start with a 0 ohm resistor and then tune from there.

[AmbystomaLabs]

There are a few things:

1. Can you confirm your code runs and advertises correctly on a development kit? You only mention changing the RTC, but it is possible that something code related is wrong. And, a DK would quickly confirm this.
2. The backside of the meander F hybrid is supposed to be connected to ground. It tunes the antenna.
3. Is the pale blue layer on your artwork just the mask layer?
4. Finally do you have a way to confirm the frequency of your 32MHz? You can either measure with a calibrated o-scope or use DTM code to bring up the radio on a channel a measure the channel error.

As RK mentioned you can really mess up the antenna and you should still pick up the radio at close range as long as the chipset is functioning well with the bad load. My suspicion is that you are using the wrong load caps and the 32MHz is off frequency. This puts the RF off frequency by the same ppm.

[Turbo J]

The NRF5x example codes require the 32768Hz quarz crystal. You omitted that, and thus need to modify the LFCLK configuration part in SOFTDEVICE_HANDLER_INIT(). Try using NRF_CLOCK_LF_SRC_SYNTH as source clock.

[AmbystomaLabs]

I believe that was implied in item 1. Plus the sofdevice init would return a fault (ie, system reset) had nine fox not modified the init to use the internal RTC.