Time out error while production test using DTM

[Cimteker]

Hello,

I am testing 9 channels for PER (1,2,3,21,22,23,37,38,39). During testing the last 3 channels I always get a single time out error in response to LE_TEST_END. I also get much higher PER for higher channels (not sure if these 2 problems are related). Anybody with a similar experience? I am using nRF51 dev kit.

Thanks

Jerry

[Edvin]

Hello,

 

During testing the last 3 channels I always get a single time out error in response to LE_TEST_END

 So that is channels 37,38 and 39?

 

I also get much higher PER for higher channels

 And this is 21, 22, 23?

What environment are you testing in? Do you have an RF shielded box, as described in section 3.2 here?

Can you also describe your test setup? Do you use a DK, or an external tester? (MT8852B)

[Cimteker]

The time out happens when testing channel 37. But it does not happen 100% of the time. I'd say 80% of the time. So it can go through all the tests without a time out.

Higher PER is for channels 37,38 and 39.

I do have an RF shielded box.

I have nRF51 dev kit connected to com9 and our customer product with Nordic's BT chip connected to com15. My script sets one chip in transmitting mode and the other in receiving mode, then I switch them around for each channel. We're testing channels 1,2,3,21,22,23 and 37,38,39. The first 6 passes with 0 packet loss, the last 3 are much worse. We're supposed to set the attenuation as per nAN-034 application note but we can't since there's probably 15-20 dB difference between 1..23 and 37..39.

thanks

[Cimteker]

Maybe a picture of our dev board will help. It's pretty old, the system was sitting idle for almost 2 years.

[Edvin]

Hello,

Can you test DK->DK, to see whether the issue is with the DK that you are using or if it actually is the DUT that is acting weird. 

What I find strange is that 37-39 is getting a lower power, as these frequencies aren't even in the same place (which you can see here).

But it may be that the antenna would require some tuning.

Could you test DK->DK and see if it behaves the same? This would suggest that it is actually the DK that you use for testing that is acting weird.

Best regards,

Edvin

[Cimteker]

Thanks Edvin,

Can I do DK->DK test with just one DK? Would I use nRFStudio for this?

[Edvin]

You would need the same setup as you have now, with the DK that you already use as a tester, and another DK programmed with the DTM example from the SDK as a Device Under Test.

The device that you tested on until now is a custom PCB, right?

Best regards,

Edvin