RF production testing using DTM

[Hitesh Rai]

Hi,

I am trying to perform RF production testing using nRF51 development kit. My DUT is another nRF51 DK. I am setting my DUT according to Figure 2 mentioned in nAN 34. I am good with the hardware set up.

I have questions about the software set up for testing as application note is not clear for software. I also tried reading through the readme file that comes with DTM library, but things are still not clear.

My questions are:

1. Which program should I flash in nRF DK module w/SMA?
2. How to get the python script running for my test?
3. Where can I find commands for performing test?
4. Where should I feed this commands? Any serial terminal?

Can you please guide me step by step for software set up?

Thanks, Hitesh

[Einar Thorsrud]

The DTM is standardized in the bluetooth spec and is intend for physical level conformance testing. The DTM example should be used for DTM, and will behave as exactly as specified in the bluetooth spec. Though it can be used for production testing, that is not what it is designed for, and it is unnecessary complex for that purpose. It is probably a better idea to base your production test on the radio test example.

In any case I will try to answer your questions, though I would recommend you not to use DTM for production testing.

1. The DTM example should be used almost without modification. The only thing you have to modify is the UART pin numbers so that they match your hardware.

2. DTM is usually used with a dedicated tester, such as the Anritsu MT8852 or similar. I am not aware of any python script that is provided by nordic. That said, it is all commands sent over UART so you can interface with it using those commands. Refer to the Bluetooth Specification Version 4.0, Vol. 6, Part F for details.

3. The commands are defined in the Bluetooth Specification Version 4.0, Vol. 6, Part F.

4. The UART interface is used to issue commands. See the Direct Test Mode example documentation.

[Hitesh Rai]

Thanks for your reply.

So if I am using radio test example and set up as Figure 2 in nAN 34,

Which program should I flash in nRF DK module w/SMA and my DUT? And how should I perform all the radio test for DUT?

Thanks, Hitesh

[Einar Thorsrud]

For some reason I missed the reference to nAN 34 in your question, and therefore misunderstood it.

Both the radio test example and the DTM example are intended to be run on the DUT. However, as described in nAN 34, the DK can be used with the DTM firmware to do some measurements. Note that the DK is not not able to give you the same accuracy as a instrument, and it is not calibrated. However, if your only need to get rough ball-park estimates (which may be enough for production testing) it should work. Unfortunately I have no experience with it.

Unless you are very cost focused you would probably be better off using the radio test example on the DUT and a real instrument as the tester, and write some software to control them both.

[Hitesh Rai]

What do you mean by real instrument? Can I not program both DUT and DK(used for tester) with Radio Test Example and work around it? And if yes can you give me the procedure details to do that?

Do you know anyone who can help me with DTM if I will be using it in future?

Thanks, Hitesh

[Einar Thorsrud]

By real instrument, I was referring to replacing the DK with proper lab equipment. The radio test example can only be used on the DUT.

I think I mislead you in my firs reply and comment, as I had not looked properly into nAN-34. Using the DTM on both the DUT and tester should work fine for production tests.

The DTM example was made to be used on the DUT with a proper tester, such as Anritsu MT8852 or similar for Conformance testing. However, as nAN 34 describes, it can be used as a tester to do simple production testing. Note that the tests will not be accurate, as the DK itself is not calibrated etc., but you will get rough estimates ("does it work or not"), which is probably good enough for production testing.