DTM (via nRF Connect) using a custom board

[CacO3]

How is it possible to run a DTM Test on a custom board using the nRF Connect Tool?

I am able to run it successfully with 2 DK boards, but I need to run it on my custom PCB (fitted with an nRF52840).

Notes:

• The DTM example in the SDK 17.1 (nRF5_SDK_17.1.0_ddde560\examples\dtm\direct_test_mode\pca10056) seems not even to work on the DK (I always get "Can not communicate with the device")!
• The DTM firmware source code provided on https://github.com/NordicSemiconductor/pc-nrfconnect-dtm does not build with the latest SDK (17.1).
• I was able to compile it using an older SDK (15.3) and it works with the latest DTM Tool and a DK board.
• How ever I need to run it on my own HW. Either through a SEGGER J-Link or UART (FTDI).

[Håkon Alseth]

Hi,

 

How is it possible to run a DTM Test on a custom board using the nRF Connect Tool?

I am able to run it successfully with 2 DK boards, but I need to run it on my custom PCB (fitted with an nRF52840).

Yes, you can use the nRF Connect for desktop "Direct test mode" PC application with any device that supports 2-wire DTM.

 

By default, the uart rxd and txd is P0.08 and P0.06, so if you use other GPIOs for your uart output, you'll need to change this mapping in the direct_test_mode firmware.

 

Kind regards,

Håkon

[CacO3]

Thanks for the quick reply!

I tried already to use the 2-wire UART. It is connect to the PC via an FTDI-usb-cable. The nRF Connect for desktop "Direct test mode" PC application does see it, how ever I always get the "Can not communicate with the device" error when I try to start the test.

Is the dtm firmware example (https://github.com/NordicSemiconductor/pc-nrfconnect-dtm/tree/master/firmware/src ) able to work with 2-wire UART? I confirmed that the RX/TX lines are mapped correctly, also I disabled the HW Flow Control (CtS/RTS) lines:

#define HWFC           false

[Håkon Alseth]

Hi,

 

Which GPIOs are you using? Note that some GPIOs are not available by default, like the NFC pins (P0.09 and P0.10).

 

Kind regards,

Håkon

[CacO3]

Yes, we use exactly those pins :

#define RX_PIN_NUMBER  9
#define TX_PIN_NUMBER  10

How ever it confuses me a bit as I tested the UART communication with an UART terminal and it worked correctly!

Also the ublox datasheet notes that those pins can be used as long as we stay under 10 kHz!
And we successfully use them for zephyr logging with 115200 baud!

[Håkon Alseth]

Hi,

 

I also run into this feature from time to time.

If you set the preprocessor define "CONFIG_NFCT_PINS_AS_GPIOS" and recompile your project, you should be able to use those pins as normal GPIOs.

If you are using the nRF52840-DK with the NFC pins, you also need to add some zero ohm resistors on the kit itself.

CacO3 said:

Also the ublox datasheet notes that those pins can be used as long as we stay under 10 kHz!

This is a recommendation from our PS, that specific GPIOs near the radio should not be used for high speed switching (PWM signal for instance), as it can potentially inject noise into the radio:

https://infocenter.nordicsemi.com/topic/ps_nrf52840/pin.html?cp=4_0_0_6_0

 

Given that DTM only sends and receives uart payloads on start and stop of a test, this is not going to be a problem.

 

Kind regards,

Håkon

[CacO3]

so is the DTM implementation in zephyr (docs.zephyrproject.org/.../CONFIG_BT_CTLR_DTM_HCI.html) compatible with the 2-wire uart and nRF Connect for desktop "Direct test mode" PC application?
I couldn't find any information or an example project for this.

[Håkon Alseth]

CacO3 said:

so is the DTM implementation in zephyr (docs.zephyrproject.org/.../CONFIG_BT_CTLR_DTM_HCI.html) compatible with the 2-wire uart and nRF Connect for desktop "Direct test mode" PC application?

Unfortunately, this is a HCI command set for DTM, which is not the same as "2-wire", which is essentially standard UART.

For zephyr, we have ported the dtm project in NCS:

https://github.com/nrfconnect/sdk-nrf/tree/main/samples/bluetooth/direct_test_mode

 

But, you can use the one from nRF5 SDK if you'd like. They're both implementing the same protocol.

DTM does not depend on a bluetooth stack, it is there to evaluate your hardware (ie. the board itself).

 

Kind regards,

Håkon

[CacO3]

Dear Håkon

Thank you for hinting me to https://github.com/nrfconnect/sdk-nrf/tree/main/samples/bluetooth/direct_test_mode

I built that sample for my own hardware (nrf52840, sender) and used a DK board as receiver (firmware installed by "Direct test mode" PC application).

I could test it successfully according to https://github.com/nrfconnect/sdk-nrf/tree/main/samples/bluetooth/direct_test_mode#testing-with-nrf-connect-for-desktop with cutecom and 19200 baud:

So the wiring is working correctly (TX=P0.10, RX=P0.09)!

Then I tried to use it with the "Direct test mode" PC application. I selected the Unknown Port

And pressed Start:

Still every time I get a "No firmware defined for selected device" and "Can not communicate with the device" error!

Notes:

• Of course I first disconnected cutecom.
• I tested the latest nrf Connect Tool (3.9.0) and DTM App 2.0.0.
• In relation to https://devzone.nordicsemi.com/f/nordic-q-a/81654/dtm-v2-00-issue-in-nrf-connect-for-desktop I also tested the older version (nrf Connect 3.7.0, DM App 1.1.7).