NRF52832 BLE radio not broadcasting

RE: NRF52832 BLE radio not broadcasting

AmbystomaLabs — Mon, 18 Jun 2018 14:00:03 GMT

You should post this as a new question. When people make custom boards there a many, many mistakes that are often made.

Just your comment about the LFRC using 3mA doesn't make any sense and points to hardware problems. The LFRC uses less than 1uA and then needs to run a cal every few seconds. Overall usage is around 2uA average.

RE: NRF52832 BLE radio not broadcasting

Vijay — Thu, 14 Jun 2018 01:20:23 GMT

Hi, can you tell me what the solution was? I have a custom board with nRF52810 and I am using a 32 MHz clock too. My BLE radio isn't working either. My code worked perfectly on the nRF52832 DK emulating as a nRF52810. I tried switching to the internal RC oscillator but that increases the current consumption to ~ 3 mA. Any help would be gladly appreciated!

- vivenkat

RE: NRF52832 BLE radio not broadcasting

mlsor — Sun, 12 Mar 2017 18:28:03 GMT

Thanks for taking a look. I got the issue resolved.

RE: NRF52832 BLE radio not broadcasting

AmbystomaLabs — Sun, 12 Mar 2017 16:23:21 GMT

Can you provide a screen shot of the grounding and vias under the nRF? Also send one out of the ground plane on bottom too. Hard to tell from the png you sent out but it looks like there are only a few vias on one side of the nRF.

RE: NRF52832 BLE radio not broadcasting

mlsor — Sun, 12 Mar 2017 06:39:46 GMT

I found a bit of code in the SDK that allowed my app to block until the softdevice enabled the HF clock. This code works and passes the wait on the dev board. It does not on my custom board, so I'm certain now that the radio issue is due to the HF clock. I might have expected the BLE init itself to error if a dependency of the radio could not be found. At any rate, that gives me something to look into.

RE: NRF52832 BLE radio not broadcasting

mlsor — Sun, 12 Mar 2017 05:38:01 GMT

"The clock control system can source the system clocks from a range of internal or external high and low frequency oscillators and distribute them to modules based upon a module’s individual requirements. Clock distribution is automated and grouped independently by module to limit current consumption in unused branches of the clock tree."

Seems like maybe it is falling back to HFINT?

RE: NRF52832 BLE radio not broadcasting

mlsor — Sun, 12 Mar 2017 05:30:58 GMT

Ok, now I'm a bit confused. I thought that having the LF clock set to the internal RC would be enough to know that the HF crystal was working. Based on the post I mentioned in the original comment, I am thinking that the HF crystal is absolutely required for the radio. However, I completely removed the HF crystal from the board, and it hasn't changed anything; flash reads/writes still work, timers, softdevice init, GPIO driving the stepper motor, it all works as before. Short of having a fairly high bandwidth probe (mine is only 60 MHz 10x probe), how can I tell that the HF oscillator is up? Is there something besides the lack of radio that I can use to troubleshoot it? I feel like perhaps I'm on to something here...

RE: NRF52832 BLE radio not broadcasting

mlsor — Sun, 12 Mar 2017 00:04:32 GMT

Yeah, I think there must be something going on, but even with a bad layout I'd expect a few centimeters of range. I've posted the antenna layout and network, it is from the reference design. That's why I was wondering if perhaps there may be some sort of fuse or register required to be set to enable the radio, something that would have come from the factory with the reference board but not with a chip from factory.

RE: NRF52832 BLE radio not broadcasting

endnode — Sat, 11 Mar 2017 22:28:45 GMT

Oh I've misunderstood that your FW is not starting at all after moving to custom board. This really looks like antenna/matching network problem. So SD init and enable functions return success and all other SD calls are working? I would try some pre-compiled examples from nRF5 SDK and if symptoms are similar then it really looks like layout/population issue.

RE: NRF52832 BLE radio not broadcasting

mlsor — Sat, 11 Mar 2017 21:14:16 GMT

Thanks for the input. I'll look through these things. It does boot and all of the functionality is there, but there is just no radio whatsoever. The layout was derived from the reference radio board layout from Nordic.

For the LF crystal, I actually have two software builds, one that uses the internal RC and another that uses the external. I was using it to determine the power savings difference. Both work with the custom board.

I'm using a timer, FDS, GPIO, it all works. I'm not using the GPIO near the radio. I tried a few different capacitance values with the HF crystal, though I assume nothing would work if this wasn't oscillating.

UPDATE: The PCB assembler provides parts libraries for their "favorite" stocked parts. It turns out that the part layout for the crystal I'm using has the pins swapped as though the person who designed it thought the 'top view' in the data sheet was a view from the bottom. I was able to turn the part 90 degrees to get the ground and clock corners to align correctly and all is well.

Between this and the other issue linked in the original post, if you are reading this because you can't see your radio, but everything else seems to be working fine, it is most likely an issue with your high frequency clock. The NRF52 will fall back to its internal HF oscillator (HFINT) if the crystal is not oscillating and your code will likely be none the wiser. To verify that the high frequency crystal is working, you can add something like this to your code after the softdevice is set up, but before you do anything that requires the radio:

err_code = sd_clock_hfclk_request();
APP_ERROR_CHECK(err_code);

uint32_t hfclk_is_running = 0;

while (!hfclk_is_running) {
    APP_ERROR_CHECK(sd_clock_hfclk_is_running(&hfclk_is_running));
}

The code above would block until the HF clock is started, and in my example it would pass on the dev board but block indefinitely on my board, until I fixed the crystal orientation. In my opinion, any library that would want to use the radio **cough BLE stack ** should have a variant of this and return an error on initialize if the HF clock (or any other dependency) is not working.

RE: NRF52832 BLE radio not broadcasting

endnode — Sat, 11 Mar 2017 20:23:11 GMT

Hi,

Not easy to debug HW issue through the forum;) but the usual differences between nRF5x boards preventing FWs to boot are:

Different LF clock source (crystal/no crystal or faulty/not precise crystal).
Different GPIO settings which is causing hard fault or other deadlock during start-up (e.g. when APP code assumes to initialize some serial or GPIOTE interface, reads button state etc.)
Layout issue (usually cause by having too tight PCB real estate and not following Nordic design guidelines) causing problem with power source or nRF5x DCDC circuit.

Debugging first one can be done by using synthesized LF clock from HF clock source during SD init (it's not officially tested by Nordic but it works). Debugging second issue can be done by removing all these sections before enabling SD and starting BLE Peripheral advertising (or simply by making sure that all GPIO values/links are correct). Third type of issue is hard to debug in FW, you can comment out DCDC enabling if you have it in the boot sequence (it helped me once to discover faulty HW design around DCDC components around nRF52).

Cheers Jan