Custom board not seen by IOS device but it is seen by NRF-Connect Desktop

[rogerarchibald]

Hi There,

I've been developing a product using the NRF52DK.  I had some custom PCB's made after I had my circuit designed, and I programmed them with the NRF52DK.  Now my boards and the NRF52832 on the DK are running the exact same firmware.

With the NRF52DK, I can connect to my service on NRF Connect for IOS and Desktop (with an NRF51 dongle). 

With my boards, I can't see them with IOS (using NRF Connect or LightBlue) but I can see them using NRF Connect Desktop.  

When I scan with NRF Connect Desktop, my boards' RSSI indicates a fairly strong signal (~ -55dBm) and I can connect and view/control all the characteristics fine.  

I'm going to continue poking around to try to understand what's different but I'm quite stumped as to why IOS will only see the NRF52832 on the DK, but NRF Connect Desktop will see either the DK or the custom board.  I've tried an iPhone and an iPad and got the same result.

Any suggestions would be greatly appreciated!

Thanks,

Roger

[AmbystomaLabs]

Make sure you don't broadcast with an Apple manufacturer ID (ie, 0x004c).  iOS segregates all 0x004c broadcasts to the CoreLocation API's, only non 0x004c show up in the CoreBluetooth API's. 

Or, if you are using CoreLocation in iOS then you can only broadcast with an Apple ID. 

[rogerarchibald]

Thank you for the suggestion, but I am fairly sure it's not an addressing issue since I can connect just fine using the same firmware on the PCA10040 DK.   

[AmbystomaLabs]

You should also measure the frequency error of your board.  Not advisable to do it directly at the 32MHz since scope probe will pull the crystal.  Instead just use DTM code to park it on a channel and measure the error.  BLE spec is max +/-150kHz error.  Ideally you will see about +/-20kHz or so error.

It is entirely possible either your PC or iOS device while still within spec is shifted just enough to see/or not see your custom board.

[rogerarchibald]

Thanks for the advice, I'll have to do some research on DTM code.

THIS is the 32MHz XTAL that I'm using, with 2% NP0 12pF caps.

[Edvin]

I am not even sure whether you use bonding, but if you could just check it, to be sure that this is not the issue, you could save yourself a couple of days of work. The reason that it works on the DK could be that the bonding data is properly stored on both devices. If this for some reason was not stored on the chip (e.g. after a chiperase), then you will get this behavior.

 

Either way, if you are sure that the bonding is not the issue, there must be something else. Either a faulty XTAL or antenna. Do you use an external antenna on the custom PCB?

 

Best regards,

Edvin

[rogerarchibald]

Hi Edvin,

I had replied to your post above to say that deleting bonding made no difference.

My board has a PCB antenna.  The image above shows the PCB design where the antenna line leaves the NRF52832 and goes through the termination circuit and out to the antenna.

Thanks,

Roger

[Edvin]

sorry. I didn't see that you responded to the other comment.

Ok. Then this sounds like there could be some issue with the antenna or the pcb. We can check the PCB layout if you like. I am not the one doing this around here, but if you can upload the entire schematics, someone can take a look at it. If you don't want to upload it in public, you can create a private ticket.

 

Best regards,

Edvin