BLE not working: I see signal on spectrum analyzer but can t see the device advertising

[nekize]

Hello, i am new to the whole NRF programming. I created my custom board with a NRF52811 SoC, without external LF crystal. I have been trying to get the device to advertise the BLE with blinky example, but i can t see it advertising with any device. I used RC for LF clock and i did flash softdevice 112 version 7.0.1. When i look for signal on spectrum analyzer i see the advertising channels where they should be and are quite strong.

Other than that my SoC works fine, i was able to program PDM microphone data sampling and writing it on the microSD card, led blinking works, just not BLE.

Does anyone have any idea what could be wrong? I put my code into the zip file.

ble_app_blinky.zip

[nekize]

Little update, i did over the weekend: I was trying the beacon example, with the same configuration as blinky, and i was running BLE scanner for 20 or so minutes and somewhere in between that interval it picked up the my board. After that i reset the device and i could not see it anymore. I have a feeling something is wrong with internal clock. I have 3 boards and it s the same with all of them.

[Susheel Nuguru]

Do you have a debugger on your board or the debugger interface? I would recommend you to start your application in debugger to see if there are any softresets happening on your device.
Seeing the signal in spectrum analyzer and not able to pick up advertising seems strange.

The device is either advertising or not,I do not think that it would transmit corrupt packets due to misconfigured clock settings.

[Susheel Nuguru]

nekize said:

So RC doesn t work. I tried now also with a 32khz XTAL crystal and i have the same symptom,

 This does not look like the issue with the clock I will try to see if we can get a nRF52811 on a DK and test this.  Due to low staffing because of summer holiday, the availability of a device to test can be delayed. I will keep you updated when i can test this.

 

nekize said:

Right now i am using a MIFA antenna design, although antenna measurements show that it should work fine for BLE frequencies. Still i will try remaking my board with different antenna design and see if that can solve my problem.

 sounds like a plan.

 

nekize said:

Is there a tutorial how to write a BLE advertisment app from scratch, if the SDK example doesn t work well,

 The problem is not with the example code, they have been used extensively in many products/projects. So i am guessing the problem is elsewhere -

[nekize]

I did found an errata for this chip where it says that internal RC can have a mistake from -25% to +40%, so i m guessig that was the issue why RC is not working.

Ok, thank you for your help and i do understand problems with summer holidays. If i figure something out in the meantime, i ll post it here.

[Susheel Nuguru]

I have found a DK with nRF52811 on it and have tested both internal RC and XTAL as clocks and in both cases advertiser was clearly visible in nRF Connect desktop app in the bluetooth analyzer until advertiser timedout and the chip went to sleep. So I think the chip is functioning properly to the examples in SDK. 

I tested this with SDK17 and HRS example.

[nekize]

Thank you for your help. I will try with another antenna. I ll post my results when i get them.

[nekize]

Just to report back. I fixed the problem. It turned out that the 32MHz crystal wasn t up to the standard. The crystal manufacturer claimed it had a better ppm then it turned out it has. So i returned those crystals and changed them with the ones nordic uses and now it all works as it should.

[Susheel Nuguru]

thanks for letting us know Nekize.