NRF52840 uart_hci : read RSSI for connected.

Question

Hi,

I'm in the process of integrating nrf52840 module in HCI over UART to a linux host.

So far I have been able to build the hci_uart in from the samples and bring it up on the host using btattach.

But one of the requirement for my work is to be able to issue the read rssi HCI command ( 0x05 0x0005 <handle>) and get the RSSI for the existing connections and NOT DEVICES IN RANGE WHICH ARE NOT CONNECTED.

so far,

connected to a LE device using bluetoothctl.

used ./hcitool con to get the connection handle.

Connections:
< LE 98:07:2D:12:57:20 handle 0 state 1 lm MASTER AUTH ENCRYPT

then,

./hcitool ./hcitool cmd 05 00005 00 00

< HCI Command: Read RSSI (0x05|0x0005) plen 2 #263 [hci0] 190.169593
Handle: 0
> HCI Event: Command Complete (0x0e) plen 7 #264 [hci0] 190.172417
Read RSSI (0x05|0x0005) ncmd 1
Status: Command Disallowed (0x0c)
Handle: 0
RSSI: 72 dBm (0x48)

it always gives constatnt 72 dBm with the Status: Command Disallowed (0x0c).

BT_CTLR_CONN_RSSI_SUPPORT

BT_CTLR_CONN_RSSI

are both set as well.

What might be the reason for this behavior?

Cheers.

_RK_ · Accepted Answer

Okay as mentioned here https://devzone.nordicsemi.com/f/nordic-q-a/70264/measuring-ble-connection-rssi-with-ncs/293389#293389 
 this is due to a bug which is said to be fixed in the next major release. 
 
 Also use of zephyr LL instead of nordic softdevice is given as an working alternative. 
 edit prj.conf as follows. 
 
 CONFIG_BT_LL_SOFTDEVICE=n 
 CONFIG_BT_LL_SW_SPLIT=y 
 
 And if you are using SES please restart and run C Make after you make the edits.

NRF52840 uart_hci : read RSSI for connected.

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