nrf51822 advertising packet not detected

RE: nrf51822 advertising packet not detected

FormerMember — Mon, 29 May 2017 11:33:50 GMT

It should not be any problem to connect the nRF52 to an Android phone. I would recommend you to contact the module manufacturer regarding this problem.

RE: nrf51822 advertising packet not detected

jemajuca — Mon, 29 May 2017 08:14:39 GMT

Hello Kristin. The module has his proprietary language abstraction over the Nordic C-based APIs, so it is just only neccesary to send the script program to it. In this case a simple demo program. It seems an Android compatibility issue with BLE.

RE: nrf51822 advertising packet not detected

FormerMember — Mon, 29 May 2017 06:23:01 GMT

@jemajuca :

1) Did you remember to program the softdevice before programming the application firmware?

2) Apart from the advertising signals not being detected, does the firmware run normally, i.e. does for example NRF_LOG print data to the terminal? If you run the chip in debug mode, does it hit main()?

RE: nrf51822 advertising packet not detected

jemajuca — Fri, 26 May 2017 10:23:40 GMT

Hello Alessandro. Thank you for your comments. We are using a nRF52 module, so I would trust it is not a hardware problem... But the thing is that some phones are not seeing or communicating with the module. It seems an other reason.

RE: nrf51822 advertising packet not detected

Alessandro Fato — Fri, 26 May 2017 08:53:22 GMT

Hi jemajuca, reviewing the schematics we identified different issues both with the matching network of the antenna and the load capacitors. We still didn't try to fix the capacitors but we planned to do some tests during this weekend. Did you try to check the load capacitors and the antenna matching circuit?

RE: nrf51822 advertising packet not detected

jemajuca — Fri, 26 May 2017 06:42:22 GMT

Alessandro, have you found the reason to that behaviour? Some similar cases here with smartphones.

RE: nrf51822 advertising packet not detected

FormerMember — Tue, 28 Mar 2017 11:17:37 GMT

My suspicion is that the problem is related to an offset of the carrier frequency: The carrier frequency output from the radio is heavily dependent on the value of the load capacitors used with the 16 MHz crystal.

On your custom board:

Which 16 MHz crystal do you use?
What is the load capacitance of that crystal?
What is the value of the load capacitors used? Is their value calculated according to the formula in the "Crystal and load capacitors" section in this tutorial?

Do you have access to a spectrum analyzer? If so, could you use the radio_test example in the SDK to check the offset of the carrier frequency?

RE: nrf51822 advertising packet not detected

Alessandro Fato — Fri, 24 Mar 2017 19:04:56 GMT

Hi Petter, the RSSI is similar and in general is around -60dbm and -70dbm. Today I went to a big tech store to try different tablets and our board was discovered by 8 out of 10 tablets. Any ideas on which could be the problem? Furthermore, the tablets that didn't discovered our board were capable to discover advertising devices with RSSI down to -90 dBm.

RE: nrf51822 advertising packet not detected

Petter Myhre — Fri, 24 Mar 2017 10:24:20 GMT

Strange. What RSSI do you get from PCA10028 on all devices? And what RSSI do you get from you custom board on all devices (that are able to receive)?