AOA Antenna Switching

[Farsley]

Hello

I am running the nrf/samples/bluetooth/direction_findinding_connectionless_rx App on an nRF52833-DK with nrf Connect SDK 2.2.0

I have set VS Code to use board nrf52833_nrf53833 and configuration to prj.conf

I am running the transmitter code on another board and in the terminal window see:

CTE[0]: samples count 45, cte type AOD 2 [us], slot durations: 2 [us], packet status CRC OK, RSSI -480
CTE[0]: samples count 45, cte type AOD 2 [us], slot durations: 2 [us], packet status CRC OK, RSSI -490
CTE[0]: samples count 45, cte type AOD 2 [us], slot durations: 2 [us], packet status CRC OK, RSSI -500

What I am not seeing is any changes on the antenna switching pins 03,04,28,29 when viewing them with an oscilloscope.

If I change

 dfe-pdu-antenna = <0x0>

to <0x5>

I can see the relevant antenna pins go high on the line:

err = bt_enable(NULL);

but they remain high and do not switch.

In a post similar to this it was suggested adding the following to the prj.conf, but I see no difference:

CONFIG_BT_CTLR_DF=y

CONFIG_BT_CTLR_DF_ANT_SWITCH_RX=y

CONFIG_BT_CTLR_DF_SCAN_CTE_RX=y

Why don't I see the antenna pins switching, Is there some setting I am missing?

Please can you tell me where in the code the antenna switching takes place.

Thank you

[Elfving]

Hello Nick,

Unfortunately, I might have to get back to you after the holidays when it comes to further details on this. Though I can tell that at least some parts of the issue is related to getting AoA and AoD mixed up. Both are considered Bluetooth direction finding, though AoA and AoD are mutually exclusive. CONFIG_BT_CTLR_DF_ANT_SWITCH_RX enables the switching on the Rx side, which is AoA. If your tag is claiming "cte type AOD", I believe it will be expecting to do antenna switching as well.

So are you trying to do AoD or AoA?

Regards and Happy Holidays,

Elfving

[Farsley]

Hello Elfving
I tried adding "CONFIG_BT_CTLR_DF_ANT_SWITCH_RX =y " to prj.conf but still I cannot see switching on the antenna lines.

Thank you

Nick

[Elfving]

Hello again Nick, and happy new year!

I believe that the sample might be configured for AoD by default. Adding the configuration might not be the right move since it is an AoA feature. Are you trying to do AoA or AoD?

Regards,

Elfving

[Farsley]

Hello Elfving

I am trying for AoA

Thank you

[Elfving]

Great. Then in the tx (beacon), you need to use the overlay file "overlay-aoa.conf", or alternatively simply copy the configurations to your prj.conf. 

Also make sure for both samples that you are using the additional board configuration file and board overlay file (although this should happen automatically, and it seems you are aware of this file already). You can modify what pins are being used for the switching in the dts overlay file. 

Did this solve the issue?

Regards,

Elfving