Test nRF52840 of output power fails with Anritsu MT8852B

[bonnet]

Hello

 We tested our product integrating the nRF52840 vers. C in DTM with the Anritsu MT8852B.

The RX tests (PER and sensitivity) pass but all TX tests (Output power, modulation) fail with error message "not enough packet".

When testing with a spectrum analyser, we do no see any RF activity. 

The device works OK in application with SoftDevice. As the RX tests pass, it proves that the UART connection is working.

We have an other test mode where the continuous transmission is triggered by an on-board SW and this works OK as well.

It seems the DTM commands of the Anritsu are not understood by the nRF52840.

Can you explain this behaviour and propose debug tests ?

Thank you.

T.Bonnet

[Kenneth]

Hi,

Have you flashed the DTM code?
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/ble_sdk_app_dtm_serial.html?cp=5_0_4_5 

Best regards,
Kenneth

[bonnet]

Hi Kenneth,

Yes we used the DTM code and we add a interface module to use our UART test pin.

As said above, the RX tests are OK but for the TX tests, the Anritsu does not detect any packets

.

I see that the Anritsu commands (following the BT core spec) do not set the TX power.

Does the DTM code use the default 0dBm TX power ?

Should we use the dtm_set_txpower to set the power ?

I am from the HW team, I do not have the code with me.

I try to get it from the SW engineer.

[Kenneth]

Hi,

I suggest you hook up a logic analyzer and look at the UART commands and responses, you should see activity as per the DTM spec in the BT core spec. If you have a DK you can use that for comparison and/or verification. It may be a voltage and/or baudrate issue.

Best regards,
Kenneth

[bonnet]

TestMT8852B.xlsx

We connected a Salae logic analyzer on the UART lines and got the traces contained in the above Excel file.

Mr Harrison from Anritsu told us that he has seen the problem before. We need to send the command

LE1MCMDVER 1. We shall debug with a new logger software from Anritsu.

[Kenneth]

Thanks for the update, let me know how it goes.

Best regards,
Kenneth