AOA Antenna Switching

RE: AOA Antenna Switching

Louis Chen — Fri, 18 Apr 2025 12:50:49 GMT

Hi Sir,

I have the same problem, but I am in AOA mode. When I modify the PDU antenna, the GPIO will change (H/L), but when I output the IQ sample, GPIO 3/4/28/29 will not switch (H/L). Can you help confirm this?

IQ sample print :

CTE[0]: samples count 45, cte type AOA, slot durations: 2 [us], packet status CRC OK, RSSI -600

Main.c :

　static const uint8_t ant_patterns[] = { 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7 };

NRF52833DK_NRF52833.overlay :

dfe-antenna-num = <8>;

dfe-pdu-antenna = <0x0>;

dfegpio0-gpios = <&gpio0 3 0>;

dfegpio1-gpios = <&gpio0 4 0>;

dfegpio2-gpios = <&gpio0 28 0>;

dfegpio3-gpios = <&gpio0 29 0>;

output files :

.config :

　CONFIG_BT_DF=y

　CONFIG_BT_DF_CONNECTIONLESS_CTE_RX=y

　CONFIG_BT_DF_CTE_RX_AOA=y

　CONFIG_BT_CTLR_DF_CTE_TX_SUPPORT=y

　CONFIG_BT_CTLR_DF_CTE_RX_SUPPORT=y

　CONFIG_BT_CTLR_DF_CTE_RX_SAMPLE_1US_SUPPORT=y

　CONFIG_BT_CTLR_DF_ANT_SWITCH_2US_SUPPORT=y

　CONFIG_BT_CTLR_DF_ANT_SWITCH_1US_SUPPORT=y

　CONFIG_BT_CTLR_CTEINLINE_SUPPORT=y

　CONFIG_BT_CTLR_DF_CTE_TX=y

　CONFIG_BT_CTLR_DF_CTE_RX_SAMPLE_1US=y

　CONFIG_BT_CTLR_DF_ANT_SWITCH_1US=y

　# CONFIG_BT_CTLR_DF_ANT_SWITCH_TX is not set

　CONFIG_BT_CTLR_DF_ANT_SWITCH_RX=y

　CONFIG_BT_CTLR_DF_CTE_RX=y

　CONFIG_BT_CTLR_DF_SCAN_CTE_RX=y

　CONFIG_BT_CTLR_DF_SAMPLE_CTE_FOR_PDU_WITH_BAD_CRC=y

　CONFIG_BT_CTLR_DF_MAX_ANT_SW_PATTERN_LEN=12

　CONFIG_BT_CTLR_DF_INIT_ANT_SEL_GPIOS=y

　CONFIG_BT_CTLR_DF_PER_SCAN_CTE_NUM_MAX=16

zephyr.dts :

radio: radio@40001000 {

compatible = "nordic,nrf-radio";

reg = < 0x40001000 0x1000 >;

interrupts = < 0x1 0x1 >;

status = "okay";

dfe-supported;

ieee802154-supported;

ble-2mbps-supported;

ble-coded-phy-supported;

tx-high-power-supported;

dfe-antenna-num = < 0x8 >;

dfe-pdu-antenna = < 0x0 >;

dfegpio0-gpios = < &gpio0 0x3 0x0 >;

dfegpio1-gpios = < &gpio0 0x4 0x0 >;

dfegpio2-gpios = < &gpio0 0x1c 0x0 >;

dfegpio3-gpios = < &gpio0 0x1d 0x0 >;

ieee802154: ieee802154 {

compatible = "nordic,nrf-ieee802154";

status = "okay";

};

RE: AOA Antenna Switching

Farsley — Mon, 16 Jan 2023 15:58:37 GMT

Thank you,
I was just looking at the receive project and forgot about the transmitter and that I had not added the file overlay-aoa.conf to the build fragment.

The clue was there all along in my original post where the receive was getting AOD transmissions:

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

RE: AOA Antenna Switching

Elfving — Thu, 05 Jan 2023 13:22:16 GMT

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

RE: AOA Antenna Switching

Farsley — Mon, 02 Jan 2023 20:43:11 GMT

Hello Elfving

I am trying for AoA

Thank you

RE: AOA Antenna Switching

Elfving — Mon, 02 Jan 2023 07:49:44 GMT

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

RE: AOA Antenna Switching

Farsley — Sun, 01 Jan 2023 17:08:29 GMT

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

RE: AOA Antenna Switching

Elfving — Tue, 27 Dec 2022 13:39:27 GMT

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