OTA Final Production Testing

[jumpingfool]

We are preparing a product (based on nRF52840) for manufacturing and currently defining the production test process.

The product is hermetically sealed with no external ports and so it is not possible to access the UART for DTM during final test. We are therefore exploring options to test the product OTA.

We have reviewed the whitepaper describing an OTA testing approach using the LiteOn Bluetooth Advanced tester at:

http://infocenter.nordicsemi.com/pdf/nwp_028.pdf

The BLE_SMART_TX_RX_PER test looks to be an excellent fit for our requirements.

However, we also need to write configuration information over BLE to the product (serial number, etc), with a Windows based PC acting as a central. So to optimise the test flow we would like to understand if we can reasonably use the PC in place of the LiteOn equipment for functional testing.

If so what operations between the PC and product would be recommended to ensure maximum verification confidence? We propose to check advertising RSSI then connect and time a data transfer burst, comparing performance a against a golden sample. Anything else we would consider? Any risks with this approach?

[Andreas]

Hi,

 

For these test you need the Litepoint IQxel instrument, this is what is doing the tests (both HW and SW). The computer is only running the test SW.

 

You could have a look at nAN34, which describes production testing using a nRF5-DK as tester. Doing so, you do not need the more expensive tester, but obviously you might not get as detailed results about exact output power, sensitivity etc. but you will get an answer to whether or not the device is funcitonal. Mind though that as you do not have access to the UART lines you can not use our DTM example out of the box, you need to configure it such that it receives the command over the air. At the end, you could do an OTA DFU.

You could implement a RSSI check if you want, just make sure the incoming power is inside the valid range for reading out RSSI. You also need to keep the window wide enough to allow for variation, both because of manufacturing but also from transmission loss if you do not place the DUT in a shielded box. Other than that you should also check that communication with the devices that are connected to the GPIOs is good.

From our perspective this should be enough. Keep in mind that you already paid for a testing all the SoC internals in our production line, you should only test for issues that might be caused by PCBA manufacturing and assembly.

 

Best regards,

Andreas

[dav01]

I see litepoints and anritsus being mentioned, can someone explain what exactly these expensive machines do that can't be done with a basic spectrum analyser + an antenna coupler.