nRF Connect Direct Test Mode get number of TX packets.

[jebolivarg]

Hello,

On the nRf Connect Direct Test Mode Firmware, is any way no know how many packets were sent on TX mode?

Regards,

Julian Bolivar

[runsiv]

Hi Julian

As far as I know there is no direct way to observe it. You can observe number of received packages if you test with another DK. You can also  observe that the number of RX packets is increasing if you use nRF Connect for Desktop to test it. 

Regards

Runar

[jebolivarg]

Hi Runsiv,

Is any way to measure the PER (Packet Error Rate) over the air interface, because on the product certification test, we need to accomplice some PER percent and the only way is to compare the ratio between the number of packets received vs the number of packets sent over a channel at max power out, and on this way get the percent of packet dropped over the air interface on some test conditions.

Regards,

Julian Bolivar

[runsiv]

Hi, below is a reply from a similar case where a customer 

We provide and implement the DTM interface as specified by Bluetooth Specification, Version 4.0 or later, Vol. 6, Part F; Direct Test Mode
https://www.bluetooth.com/specifications/specs/core-specification-5-4/ 

So we do rely on the documentation from Bluetooth on how to use the DTM interface. On the same page you can also find the RF-PHY Test Suite that describe the definition of the packet error rate.

That said, see this answer:
https://devzone.nordicsemi.com/f/nordic-q-a/62935/direct-test-mode-receiver-answer/259137 

The short explaination:

Setup one board to transmit using LE_TRANSMITTER_TEST command (this will send packet at a fixed interval as specified by BT spec, e.g. every 0.625ms with default packet length).

Setup one board to receive using LE_RECEIVER_TEST command, wait for instance 1000ms, end test using LE_TEST_END. Then you will receive the numbers of packets received during the 1000ms period. The packet error rate is then 1 - the number of received packets divided by the number of packets that was sent during the 1000ms period (the number of packets sent in this case can be calculated by 1000ms / 0.625ms = 1600 packets). So if you received for instance 1550packets, then the packet error rate was 1 - 1550/1600 = 0.031 = 3.1%.

I would also have a look at this thread where another nordic employee describes the use of Radio Test or DTM. From the sound of it Radio test might be a better fit for you

Regards

Runar