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Direct Test Mode (DTM) - Upper Tester Selection

Mateusz

Hi,

The Bluetooth Core specification states that:

Direct Test Mode shall be set up using one of two alternate methods:
1. over HCI (as defined in Section 2) or
2. through a 2-wire UART interface (as defined in Section 3)
Each DUT shall implement one of the two Direct Test Mode methods in order to
test the Low Energy PHY layer.

Per Bluetooth Core Specification Version 5.2 | Vol 6, Part F, Section 1.

The nRF5 SDK, v17.1.0, DTM Example states the following:

main.c may be replaced with other interface implementations, such as an HCI interface, USB, or another interface required by the Upper Tester.

According to the Bluetooth Core Spec, USB (or some other interface) may not be used, correct? At least, this is how I understand the Core Spec quote above.

The are also some previous threads that discuss alternative interfaces, here on the DevZone, such as in this thread. I also found a related issue with Nordic's Direct Test Mode application.

In the end, is it up to the test house to sign off on the interface of choice, ignoring / bypassing Bluetooth Core specs?

  • +1

    Hi,

    I just want to mention this first, to avoid any confusion. We only support DTM 2-wire (UART) interface in nRF5 SDK. 

    According to the Bluetooth Core Spec, USB (or some other interface) may not be used, correct? At least, this is how I understand the Core Spec quote above.

    HCI can, per the specification, be used for DTM testing, and that can technically use any transport layer, as long as both sides uses the same transport.

    In the end, is it up to the test house to sign off on the interface of choice, ignoring / bypassing Bluetooth Core specs?

    If the problem is only on a transport layer level, I would recommend exposing two GPIOs, and please note that these GPIOs can be connected via a test-pin or test-point, and use those for DTM.

     

    Kind regards,

    Håkon

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